Android巧用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：

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 ;    @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);       }     }   }  } 

源码下载：左右滑动ViewPager

2、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

 @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

@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];   } 

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