20 ViewPager Demo4自动轮播

MainActivity.java

思想：才用非常大的数 让其看起来可以循环轮播图片并且用户可以从尽头滑到首图的特点 、

package com.qf.day20_viewpager_demo4;

import java.util.ArrayList;
import java.util.List;

import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

public class MainActivity extends Activity {

    private ViewPager viewPager;
    private int[] imags = {R.drawable.image1,R.drawable.image2,R.drawable.image3};
    private List<ImageView> list;

    private Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {

            viewPager.setCurrentItem(viewPager.getCurrentItem()+1);

            handler.sendEmptyMessageDelayed(1, 2000);

        };
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewPager = (ViewPager) findViewById(R.id.viewPager);

        //数据源
        list = new ArrayList<ImageView>();
        if(imags.length<4){
            for(int i=0;i<imags.length*4;i++){
                ImageView imageView = new ImageView(getApplicationContext());
                imageView.setImageResource(imags[i%imags.length]);
                list.add(imageView);
            }
        }else{
            for(int i=0;i<imags.length;i++){
                ImageView imageView = new ImageView(getApplicationContext());
                imageView.setImageResource(imags[i]);
                list.add(imageView);
            }
        }

        //adapter

        viewPager.setAdapter(new MyAdapter());

        //让程序默认展示第一条数据
        viewPager.setCurrentItem(Integer.MAX_VALUE/2-Integer.MAX_VALUE/2%list.size());

        //使用Handler发送消息
        handler.sendEmptyMessageDelayed(1, 2000);

        //自动轮播
//      new Thread(){
//          public void run() {
//              while(true){
//                  try {
//                      Thread.sleep(2000);
//                  } catch (InterruptedException e) {
//                      // TODO Auto-generated catch block
//                      e.printStackTrace();
//                  }
//                  runOnUiThread(new Runnable() {
//
//                      @Override
//                      public void run() {
//                          // 方式一
////                            int pos = viewPager.getCurrentItem();
////                            if(pos == imags.length-1){
////                                viewPager.setCurrentItem(0,false);
////                            }else{
////                                viewPager.setCurrentItem(viewPager.getCurrentItem()+1);
////                            }
//
//
//                          viewPager.setCurrentItem(viewPager.getCurrentItem()+1);
//                      }
//                  });
//              }
//          };
//      }.start();
    }

    public class MyAdapter extends PagerAdapter{

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return Integer.MAX_VALUE;//设置一个最大值
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            // TODO Auto-generated method stub
            container.addView(list.get(position%list.size()));
            return list.get(position%list.size());
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            // TODO Auto-generated method stub
//          super.destroyItem(container, position, object);
            container.removeView(list.get(position%list.size()));
        }

        @Override
        public boolean isViewFromObject(View arg0, Object arg1) {
            // TODO Auto-generated method stub
            return arg0 == arg1;
        }

    }

}

布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
         />

</RelativeLayout>