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

<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

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 ;@Overrideprotected 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IDimgIdArray = 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AdapterviewPager.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{@Overridepublic int getCount() {return Integer.MAX_VALUE;}@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1;}@Overridepublic 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 */@Overridepublic Object instantiateItem(View container, int position) {((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0);return mImageViews[position % mImageViews.length];}}@Overridepublic void onPageScrollStateChanged(int arg0) {}@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {}@Overridepublic 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

@Overridepublic 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

@Overridepublic 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];}