Android高手进阶教程(三)之----Android 中自定义View的应用.

大家好我们今天的教程是在Android 教程中自定义View 的学习，对于初学着来说，他们习惯了Android 传统的页面布局方式，如下代码:
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<?xml version="1.0" encoding="utf-8"?>

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/hello"

/>

</LinearLayout>

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

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/hello"

/>

</LinearLayout>

当然上面的布局方式可以帮助我们完成简单应用的开发了，但是如果你想写一个复杂的应用，这样就有点牵强了，大家不信可以下源码都研究看看，高手写的布局方式，如上面的布局高手通常是这样写的:
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<?xml version="1.0" encoding="utf-8"?>

<A>

<B></B>

</A>

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

<A>

<B></B>

</A>

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其中A extends LinerLayout, B extends TextView.
其中A extends LinerLayout, B extends TextView.
为了帮助大家更容易理解，我写了一个简单的Demo ,具体步骤如下：
首先新建一个Android 工程 命名为ViewDemo .
然后自定义一个View 类，命名为MyView(extends View) .代码如下:

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package com.android.tutor;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Rect;

import android.graphics.Paint.Style;

import android.util.AttributeSet;

import android.view.View;

public class MyView extends View {

private Paint mPaint;

private Context mContext;

private static final String mString = "Welcome to Mr Wei's blog";

public MyView(Context context) {

super(context);

}

public MyView(Context context,AttributeSet attr)

{

super(context,attr);

}

@Override

protected void onDraw(Canvas canvas) {

// TODO Auto-generated method stub

super.onDraw(canvas);

mPaint = new Paint();

//设置画笔颜色

mPaint.setColor(Color.RED);

//设置填充

mPaint.setStyle(Style.FILL);

//画一个矩形,前俩个是矩形左上角坐标，后面俩个是右下角坐标

canvas.drawRect(new Rect(10, 10, 100, 100), mPaint);

mPaint.setColor(Color.BLUE);

//绘制文字

canvas.drawText(mString, 10, 110, mPaint);

}

}

package com.android.tutor;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Rect;

import android.graphics.Paint.Style;

import android.util.AttributeSet;

import android.view.View;

public class MyView extends View {

private Paint mPaint;

private Context mContext;

private static final String mString = "Welcome to Mr Wei's blog";

public MyView(Context context) {

super(context);

}

public MyView(Context context,AttributeSet attr)

{

super(context,attr);

}

@Override

protected void onDraw(Canvas canvas) {

// TODO Auto-generated method stub

super.onDraw(canvas);

mPaint = new Paint();

//设置画笔颜色

mPaint.setColor(Color.RED);

//设置填充

mPaint.setStyle(Style.FILL);

//画一个矩形,前俩个是矩形左上角坐标，后面俩个是右下角坐标

canvas.drawRect(new Rect(10, 10, 100, 100), mPaint);

mPaint.setColor(Color.BLUE);

//绘制文字

canvas.drawText(mString, 10, 110, mPaint);

}

}

然后将我们自定义的View 加入到main.xml 布局文件中,代码如下:

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

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/hello"

/>

<com.android.tutor.MyView

android:layout_width="fill_parent"

android:layout_height="fill_parent"

/>

</LinearLayout>

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

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/hello"

/>

<com.android.tutor.MyView

android:layout_width="fill_parent"

android:layout_height="fill_parent"

/>

</LinearLayout>

最后执行之，效果如下图:



OK,大功告成，今天就写到这里，开始做饭了，老婆孩子等我做饭了，lol~

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