Android 使用ViewPager实现左右循环滑动图片

ViewPager这个小demo实现的是可以左右循环滑动图片，下面带索引，滑到最后一页在往右滑动就要第一页，第一页往左滑动就到最后一页，先上效果图，用美女图片是我一贯的作风，呵呵



1. 首先看一些layout下的xml

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

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical" >

<android.support.v4.view.ViewPager

android:id="@+id/viewPager"

android:layout_width="fill_parent"

android:layout_height="wrap_content" />

<RelativeLayout

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:orientation="vertical" >

<LinearLayout

android:id="@+id/viewGroup"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_alignParentBottom="true"

android:layout_marginBottom="30dp"

android:gravity="center_horizontal"

android:orientation="horizontal" >

</LinearLayout>

</RelativeLayout>

</FrameLayout>

使用ViewPager首先需要引入android-support-v4.jar这个jar包。自己不要忘记加

[java] view plaincopy





package com.example.viewpagerdemo;

import android.app.Activity;

import android.os.Bundle;

import android.support.v4.view.PagerAdapter;

import android.support.v4.view.ViewPager;

import android.support.v4.view.ViewPager.OnPageChangeListener;

import android.view.View;

import android.view.ViewGroup;

import android.view.ViewGroup.LayoutParams;

import android.widget.ImageView;

import android.widget.LinearLayout;

public class TwoActivity extends Activity implements OnPageChangeListener{

/**

* ViewPager

*/

private ViewPager viewPager;

/**

* 装点点的ImageView数组

*/

private ImageView[] tips;

/**

* 装ImageView数组

*/

private ImageView[] mImageViews;

/**

* 图片资源id

*/

private int[] imgIdArray ;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

ViewGroup group = (ViewGroup)findViewById(R.id.viewGroup);

viewPager = (ViewPager) findViewById(R.id.viewPager);

//载入图片资源ID

imgIdArray = new int[]{R.drawable.item01, R.drawable.item02, R.drawable.item03, R.drawable.item04,

R.drawable.item05,R.drawable.item06, R.drawable.item07, R.drawable.item08};

//将点点加入到ViewGroup中

tips = new ImageView[imgIdArray.length];

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

ImageView imageView = new ImageView(this);

imageView.setLayoutParams(new LayoutParams(10,10));

tips[i] = imageView;

if(i == 0){

tips[i].setBackgroundResource(R.drawable.page_indicator_focused);

}else{

tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused);

}

LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(new ViewGroup.LayoutParams(LayoutParams.WRAP_CONTENT,

LayoutParams.WRAP_CONTENT));

layoutParams.leftMargin = 5;

layoutParams.rightMargin = 5;

group.addView(imageView, layoutParams);

}

//将图片装载到数组中

mImageViews = new ImageView[imgIdArray.length];

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

ImageView imageView = new ImageView(this);

mImageViews[i] = imageView;

imageView.setBackgroundResource(imgIdArray[i]);

}

//设置Adapter

viewPager.setAdapter(new MyAdapter());

//设置监听，主要是设置点点的背景

viewPager.setOnPageChangeListener(this);

//设置ViewPager的默认项, 设置为长度的100倍，这样子开始就能往左滑动

viewPager.setCurrentItem((mImageViews.length) * 100);

}

/**

*

* @author xiaanming

*

*/

public class MyAdapter extends PagerAdapter{

@Override

public int getCount() {

return Integer.MAX_VALUE;

}

@Override

public boolean isViewFromObject(View arg0, Object arg1) {

return arg0 == arg1;

}

@Override

public void destroyItem(View container, int position, Object object) {

((ViewPager)container).removeView(mImageViews[position % mImageViews.length]);

}

/**

* 载入图片进去，用当前的position 除以 图片数组长度取余数是关键

*/

@Override

public Object instantiateItem(View container, int position) {

((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0);

return mImageViews[position % mImageViews.length];

}

}

@Override

public void onPageScrollStateChanged(int arg0) {

}

@Override

public void onPageScrolled(int arg0, float arg1, int arg2) {

}

@Override

public void onPageSelected(int arg0) {

setImageBackground(arg0 % mImageViews.length);

}

/**

* 设置选中的tip的背景

* @param selectItems

*/

private void setImageBackground(int selectItems){

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

if(i == selectItems){

tips[i].setBackgroundResource(R.drawable.page_indicator_focused);

}else{

tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused);

}

}

}

}

代码下载

上面的代码中，当只有3张图片或者2张图片的时候，滑动存在BUG问题的修改如下

destroyItem(View container, int position, Object object)方法中不removeView

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@Override

public void destroyItem(View container, int position, Object object) {

// ((ViewPager)container).removeView(mImageViews[position % mImageViews.length]);

}

instantiateItem(View container, int position)增加异常扑捉

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@Override

public Object instantiateItem(View container, int position) {

try {

((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0);

}catch(Exception e){

//handler something

}

return mImageViews[position % mImageViews.length];

}