Android 使用ViewPager实现左右循环滑动图片

来源：互联网发布：神之浩劫画质优化编辑：程序博客网时间：2024/04/27 18:08

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 plaincopy
<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

[java] view plaincopy
    @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 plaincopy
@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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