Android中常见的热门标签的流式布局的实现——云标签

一、概述：

在日常的app使用中，我们会在android 的app中看见 热门标签等自动换行的流式布局，今天，我们就来看看如何

自定义一个类似热门标签那样的流式布局吧（源码下载在下面最后给出）

类似的自定义布局。下面我们就来详细介绍流式布局的应用特点以及用的的技术点：

1.流式布局的特点以及应用场景

特点：当上面一行的空间不够容纳新的TextView时候，

才开辟下一行的空间

　　原理图：

　　


场景：主要用于关键词搜索或者热门标签等场景

2.自定义ViewGroup,重点重写下面两个方法

1、onMeasure:测量子view的宽高，设置自己的宽和高

2、onLayout:设置子view的位置

onMeasure:根据子view的布局文件中属性，来为子view设置测量模式和测量值

测量=测量模式+测量值；

测量模式有3种：

EXACTLY：表示设置了精确的值，一般当childView设置其宽、高为精确值、match_parent时，ViewGroup会将其设置为EXACTLY；

AT_MOST：表示子布局被限制在一个最大值内，一般当childView设置其宽、高为wrap_content时，ViewGroup会将其设置为AT_MOST；

UNSPECIFIED：表示子布局想要多大就多大，一般出现在AadapterView的item的heightMode中、ScrollView的childView的heightMode中；此种模式比较少见。

3.LayoutParams

ViewGroup LayoutParams :每个 ViewGroup 对应一个 LayoutParams; 即 ViewGroup -> LayoutParams

getLayoutParams 不知道转为哪个对应的LayoutParams ,其实很简单，就是如下：

子View.getLayoutParams 得到的LayoutParams对应的就是 子View所在的父控件的LayoutParams;

例如，LinearLayout 里面的子view.getLayoutParams ->LinearLayout.LayoutParams

所以 咱们的FlowLayout 也需要一个LayoutParams，由于上面的效果图是子View的 margin，

所以应该使用MarginLayoutParams。即FlowLayout->MarginLayoutParams

4.最后来看看实现的最终效果图：



二、热门标签的流式布局的实现：

1. 自定义热门标签的ViewGroup实现

　　根据上面的技术分析，自定义类继承于ViewGroup，并重写 onMeasure和onLayout等方法。具体实现代码如下：

[plain] view
plaincopy

package com.czm.flowlayout;

import java.util.ArrayList;

import java.util.List;

import android.content.Context;

import android.util.AttributeSet;

import android.view.View;

import android.view.ViewGroup;

/**

*

* @author caizhiming

* @created on 2015-4-13

*/

public class XCFlowLayout extends ViewGroup{

//存储所有子View

private List<List<View>> mAllChildViews = new ArrayList<>();

//每一行的高度

private List<Integer> mLineHeight = new ArrayList<>();

public XCFlowLayout(Context context) {

this(context, null);

// TODO Auto-generated constructor stub

}

public XCFlowLayout(Context context, AttributeSet attrs) {

this(context, attrs, 0);

// TODO Auto-generated constructor stub

}

public XCFlowLayout(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

// TODO Auto-generated constructor stub

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

// TODO Auto-generated method stub

//父控件传进来的宽度和高度以及对应的测量模式

int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);

int modeWidth = MeasureSpec.getMode(widthMeasureSpec);

int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);

int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

//如果当前ViewGroup的宽高为wrap_content的情况

int width = 0;//自己测量的 宽度

int height = 0;//自己测量的高度

//记录每一行的宽度和高度

int lineWidth = 0;

int lineHeight = 0;

//获取子view的个数

int childCount = getChildCount();

for(int i = 0;i < childCount; i ++){

View child = getChildAt(i);

//测量子View的宽和高

measureChild(child, widthMeasureSpec, heightMeasureSpec);

//得到LayoutParams

MarginLayoutParams lp = (MarginLayoutParams) getLayoutParams();

//子View占据的宽度

int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;

//子View占据的高度

int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;

//换行时候

if(lineWidth + childWidth > sizeWidth){

//对比得到最大的宽度

width = Math.max(width, lineWidth);

//重置lineWidth

lineWidth = childWidth;

//记录行高

height += lineHeight;

lineHeight = childHeight;

}else{//不换行情况

//叠加行宽

lineWidth += childWidth;

//得到最大行高

lineHeight = Math.max(lineHeight, childHeight);

}

//处理最后一个子View的情况

if(i == childCount -1){

width = Math.max(width, lineWidth);

height += lineHeight;

}

}

//wrap_content

setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width,

modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height);

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

}

@Override

protected void onLayout(boolean changed, int l, int t, int r, int b) {

// TODO Auto-generated method stub

mAllChildViews.clear();

mLineHeight.clear();

//获取当前ViewGroup的宽度

int width = getWidth();

int lineWidth = 0;

int lineHeight = 0;

//记录当前行的view

List<View> lineViews = new ArrayList<View>();

int childCount = getChildCount();

for(int i = 0;i < childCount; i ++){

View child = getChildAt(i);

MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

int childWidth = child.getMeasuredWidth();

int childHeight = child.getMeasuredHeight();

//如果需要换行

if(childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width){

//记录LineHeight

mLineHeight.add(lineHeight);

//记录当前行的Views

mAllChildViews.add(lineViews);

//重置行的宽高

lineWidth = 0;

lineHeight = childHeight + lp.topMargin + lp.bottomMargin;

//重置view的集合

lineViews = new ArrayList();

}

lineWidth += childWidth + lp.leftMargin + lp.rightMargin;

lineHeight = Math.max(lineHeight, childHeight + lp.topMargin + lp.bottomMargin);

lineViews.add(child);

}

//处理最后一行

mLineHeight.add(lineHeight);

mAllChildViews.add(lineViews);

//设置子View的位置

int left = 0;

int top = 0;

//获取行数

int lineCount = mAllChildViews.size();

for(int i = 0; i < lineCount; i ++){

//当前行的views和高度

lineViews = mAllChildViews.get(i);

lineHeight = mLineHeight.get(i);

for(int j = 0; j < lineViews.size(); j ++){

View child = lineViews.get(j);

//判断是否显示

if(child.getVisibility() == View.GONE){

continue;

}

MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

int cLeft = left + lp.leftMargin;

int cTop = top + lp.topMargin;

int cRight = cLeft + child.getMeasuredWidth();

int cBottom = cTop + child.getMeasuredHeight();

//进行子View进行布局

child.layout(cLeft, cTop, cRight, cBottom);

left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;

}

left = 0;

top += lineHeight;

}

}

/**

* 与当前ViewGroup对应的LayoutParams

*/

@Override

public LayoutParams generateLayoutParams(AttributeSet attrs) {

// TODO Auto-generated method stub

return new MarginLayoutParams(getContext(), attrs);

}

}

2.相关的布局文件：

引用自定义控件：

[plain] view
plaincopy

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/container"

android:layout_width="match_parent"

android:layout_height="match_parent" >

<com.czm.flowlayout.XCFlowLayout

android:id="@+id/flowlayout"

android:layout_width="match_parent"

android:layout_height="match_parent" >

</com.czm.flowlayout.XCFlowLayout>

</RelativeLayout>

TextView的样式文件：

[plain] view
plaincopy

<?xml version="1.0" encoding="utf-8"?>

<shape xmlns:android="http://schemas.android.com/apk/res/android" >

<solid android:color="#666666" />

<corners android:radius="10dp" />

<padding

android:left="5dp"

android:right="5dp"

android:top="5dp"

android:bottom="5dp"

/>

</shape>

三、使用该自定义布局控件类

最后，如何使用该自定义的热门标签控件类呢？很简单，请看下面实例代码：

[plain] view
plaincopy

package com.czm.flowlayout;

import android.app.Activity;

import android.graphics.Color;

import android.os.Bundle;

import android.view.ViewGroup.LayoutParams;

import android.view.ViewGroup.MarginLayoutParams;

import android.widget.TextView;

/**

*

* @author caizhiming

* @created on 2015-4-13

*/

public class MainActivity extends Activity {

private String mNames[] = {

"welcome","android","TextView",

"apple","jamy","kobe bryant",

"jordan","layout","viewgroup",

"margin","padding","text",

"name","type","search","logcat"

};

private XCFlowLayout mFlowLayout;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

initChildViews();

}

private void initChildViews() {

// TODO Auto-generated method stub

mFlowLayout = (XCFlowLayout) findViewById(R.id.flowlayout);

MarginLayoutParams lp = new MarginLayoutParams(

LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);

lp.leftMargin = 5;

lp.rightMargin = 5;

lp.topMargin = 5;

lp.bottomMargin = 5;

for(int i = 0; i < mNames.length; i ++){

TextView view = new TextView(this);

view.setText(mNames[i]);

view.setTextColor(Color.WHITE);

view.setBackgroundDrawable(getResources().getDrawable(R.drawable.textview_bg));

mFlowLayout.addView(view,lp);

}

}

}

四、源码下载

最后给出源码的下载：http://download.csdn.net/detail/jdsjlzx/8784571

这里引用另一个高手的实现，

摘要

新项目用到了一种全新布局————Android标签流式布局的功能，正好一直说给大家讲自定义控件的实现，今天就为大家讲一种android流式布局的实现。

本文原创，转载请注明地址：http://blog.kymjs.com/

正文

在日常的app使用中，我们会在android 的app中看见热门标签等自动换行的流式布局，今天，我们就来看看如何自定义一个类似热门标签那样的流式布局吧（源码下载在下面最后给出）





这个控件并不是我实现的，代码是从网上搜流式布局找到的。我只是为大家讲解一下实现过程以及原理。

先看代码

<code class="language-java"><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="kd"><span class="kwd">class</span></span><span class="pln"> </span><span class="nc"><span class="typ">FlowLayout</span></span><span class="pln"> </span><span class="kd"><span class="kwd">extends</span></span><span class="pln"> </span><span class="n"><span class="typ">ViewGroup</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="kd"><span class="kwd">private</span></span><span class="pln"> </span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="c1"><span class="com">//每个item纵向间距</span></span><span class="pln">
</span><span class="kd"><span class="kwd">private</span></span><span class="pln"> </span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="c1"><span class="com">//每个item横向间距</span></span><span class="pln">

</span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="nf"><span class="typ">FlowLayout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="typ">Context</span></span><span class="pln"> </span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="kd"><span class="kwd">super</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">);</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="nf"><span class="typ">FlowLayout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="typ">Context</span></span><span class="pln"> </span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="typ">AttributeSet</span></span><span class="pln"> </span><span class="n"><span class="pln">attrs</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="kd"><span class="kwd">super</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">attrs</span></span><span class="o"><span class="pun">);</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">setHorizontalSpacing</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">setVerticalSpacing</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="nd"><span class="lit">@Override</span></span><span class="pln">
</span><span class="kd"><span class="kwd">protected</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">onMeasure</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">selfWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">resolveSize</span></span><span class="o"><span class="pun">(</span></span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">);</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingLeft</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingTop</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingRight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingBottom</span></span><span class="o"><span class="pun">();</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">;</span></span><span class="pln">

</span><span class="c1"><span class="com">//通过计算每一个子控件的高度，得到自己的高度</span></span><span class="pln">
</span><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">
</span><span class="n"><span class="typ">LayoutParams</span></span><span class="pln"> </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getLayoutParams</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">measure</span></span><span class="o"><span class="pun">(</span></span><span class="pln">
</span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="o"><span class="pun">,</span></span><span class="pln">
</span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">width</span></span><span class="o"><span class="pun">),</span></span><span class="pln">
</span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="o"><span class="pun">,</span></span><span class="pln">
</span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">height</span></span><span class="o"><span class="pun">));</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">

</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">

</span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">selfWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln"> </span><span class="k"><span class="kwd">else</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">wantedHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">setMeasuredDimension</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">selfWidth</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">resolveSize</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">wantedHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">));</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">

</span><span class="nd"><span class="lit">@Override</span></span><span class="pln">
</span><span class="kd"><span class="kwd">protected</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">onLayout</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">boolean</span></span><span class="pln"> </span><span class="n"><span class="pln">changed</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">l</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">t</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">r</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">b</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">myWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">r</span></span><span class="pln"> </span><span class="o"><span class="pun">-</span></span><span class="pln"> </span><span class="n"><span class="pln">l</span></span><span class="o"><span class="pun">;</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingLeft</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingTop</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingRight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="o"><span class="pun">;</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">;</span></span><span class="pln">

</span><span class="c1"><span class="com">//根据子控件的宽高，计算子控件应该出现的位置。</span></span><span class="pln">
</span><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">

</span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getVisibility</span></span><span class="o"><span class="pun">()</span></span><span class="pln"> </span><span class="o"><span class="pun">==</span></span><span class="pln"> </span><span class="n"><span class="typ">View</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">GONE</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="k"><span class="kwd">continue</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">

</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">

</span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">myWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">layout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span></code>

从控件创建过程说起

当这个流式布局在被加载如内存并显示在屏幕上这一过程中，首先会调用view.measure(w,h)这个方法，表示测量view的宽度与高度，其中参数w与h分别表示这个控件的父控件的宽高。
在view.measure()方法的调用过程中又会调用view本身的一个回调方法,onMeasure()，这个是view自身的一个回调方法，用于让开发者在自定义View的时候重新计算自身的大小。一般会在这个方法中循环遍历，计算出这个控件的全部子孙控件的宽高。
在View的宽高计算完成以后，考虑将这个控件显示到屏幕的指定位置上，此时view的onLayout()方法会被调用。 一般同时会在这个方法中计算出全部子孙控件在这个控件中的位置。

可能基本流程有些枯燥，接下来结合代码看看。

流布局的实现

看到onMeasure()方法中的这段： //通过计算每一个子控件的高度，得到自己的高度

<code class="language-java"><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">
</span><span class="n"><span class="typ">LayoutParams</span></span><span class="pln"> </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getLayoutParams</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">measure</span></span><span class="o"><span class="pun">(</span></span><span class="pln">
</span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="o"><span class="pun">,</span></span><span class="pln">
</span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">width</span></span><span class="o"><span class="pun">),</span></span><span class="pln">
</span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="o"><span class="pun">,</span></span><span class="pln">
</span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">height</span></span><span class="o"><span class="pun">));</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">

</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">

</span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">selfWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln"> </span><span class="k"><span class="kwd">else</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span></code>

首先通过循环，遍历这个控件的所有子控件，同时调用子控件的measure()方法，这时measure方法的两个参数是控件能给这个子控件的最大宽高(我们都知道的，子控件再大，显示的大小也不能比父控件还大)。这里getChildMeasureSpec()方法的作用是用来计算一个合适子视图的尺寸大小（宽度或者高度)，结合我们从子视图的LayoutParams所给出的MeasureSpec信息来获取最合适的结果。比如，如果这个View知道自己的大小尺寸（因为它本身的MeasureSpec的model为Exactly,）并且子视图的大小恰好跟父窗口一样大，父窗口必须用给定的大小去layout子视图

参数含义：spec 父窗口传递给子视图的大小和模式

padding 父窗口的边距，也就是xml中的android:padding

childDimension 子视图想要绘制的准确大小，但最终不一定绘制此值

当得到了每一个子控件的大小以后，再要计算自己的宽高就简单了。

int wantedHeight = childTop + lineHeight + paddingBottom;

同理，在onLayout中的这一句

<code class="language-java"><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">

</span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getVisibility</span></span><span class="o"><span class="pun">()</span></span><span class="pln"> </span><span class="o"><span class="pun">==</span></span><span class="pln"> </span><span class="n"><span class="typ">View</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">GONE</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="k"><span class="kwd">continue</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">

</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">
</span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">

</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">

</span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">myWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span><span class="pln">
</span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">layout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">
</span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln">
</span><span class="o"><span class="pun">}</span></span></code>

首先通过循环遍历，控制每个item子控件的显示位置，如果当前行还能放得下一个item，就放到当前行，如果放不下就放到下一行的最左边。

最终，遍历完成，也就相当于把自己的位置显示完成了。

效果截图

流式布局