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

[html] view
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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
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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

[java] view
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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

[java] view
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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];