Android ViewPager实现图片轮翻效果

很多App都有这种效果，特别一些电商类的App，顶部每隔几秒钟会向右翻页显示下张图片，用来作推广或者内容展示用的。今天来简单地模仿一下，还自带一个自动跳动的小功能（底部有几个小点，图片移动的时候，点的状态也在变化），用定时器来实现不难。

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

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;
import android.widget.TextView;

public class MainActivity extends Activity implements OnPageChangeListener {

protected static final String TAG = "MainActivity";
private List<ImageView> imageViewList;
private ViewPager mViewPager;
private final int[] imageResIDs = {
  R.drawable.a,
  R.drawable.b,
  R.drawable.c,
  R.drawable.d,
  R.drawable.e
};
private final String[] imageDescriptions = {
  "巩俐不低俗，我就不能低俗",
  "扑树又回来啦！再唱经典老歌引万人大合唱",
  "揭秘北京电影如何升级",
  "乐视网TV版大派送",
  "热血 * 丝的反杀"
};
private TextView tvImageDescription; // 图片描述
private LinearLayout llPointGroup;  // 点控件的组
private int previousPosition = 0;  // viewpager选中的前一个position
private boolean isStop = false; // 控制循环的子线程是否停止

private Handler handler = new Handler(){

@Override
 public void handleMessage(Message msg) {
  super.handleMessage(msg);

mViewPager.setCurrentItem(mViewPager.getCurrentItem() + 1);
 }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

initView();

new Thread(new Runnable() {

@Override
  public void run() {
   // 每两秒钟向主线程发送一条消息, 切换viewpager的界面
   while(!isStop) {
    SystemClock.sleep(2000);

handler.sendEmptyMessage(0);
   }
   Log.i(TAG, "循环线程停止了");
  }}).start();
}

@Override
protected void onDestroy() {
 isStop = true;
 super.onDestroy();
}

private void initView() {
 mViewPager = (ViewPager) findViewById(R.id.viewpager);
 llPointGroup = (LinearLayout) findViewById(R.id.ll_point_group);
 tvImageDescription = (TextView) findViewById(R.id.tv_image_description);

imageViewList = new ArrayList<ImageView>();

ImageView iv;
 View pointView;
 LayoutParams params;
 for (int i = 0; i < imageResIDs.length; i++) {
  iv = new ImageView(this);
  iv.setBackgroundResource(imageResIDs[i]);
  imageViewList.add(iv);

// 根据图片添加点
  pointView = new View(this);
  params = new LayoutParams(5, 5);
  params.leftMargin = 5;
  pointView.setLayoutParams(params);
  pointView.setEnabled(false);
  pointView.setBackgroundResource(R.drawable.point_bg);
  llPointGroup.addView(pointView);
 }

MyPagerAdapter mAdapter = new MyPagerAdapter();
 mViewPager.setAdapter(mAdapter);
 mViewPager.setOnPageChangeListener(this);

int item = (Integer.MAX_VALUE / 2) - ((Integer.MAX_VALUE / 2) ％ imageViewList.size());
 mViewPager.setCurrentItem(item);  // 设置当前选中的item的position

tvImageDescription.setText(imageDescriptions[previousPosition]);
 llPointGroup.getChildAt(previousPosition).setEnabled(true); // 第一点被选中
}

class MyPagerAdapter extends PagerAdapter {

@Override
 public int getCount() {
  return Integer.MAX_VALUE;
 }

/**
  * 移动的对象和进来的对象如果是同一个就返回true, 代表复用view对象
  * false 使用object对象
  */
 @Override
 public boolean isViewFromObject(View arg0, Object arg1) {
  return arg0 == arg1;
 }

/**
  * 需要销毁的对象的position传进来
  */
 @Override
 public void destroyItem(ViewGroup container, int position, Object object) {
  // 移除掉指定position的对象
  mViewPager.removeView(imageViewList.get(position ％ imageViewList.size()));
 }

/**
  * 加载position位置的view对象
  */
 @Override
 public Object instantiateItem(ViewGroup container, int position) {
  // 添加指定position的对象
  mViewPager.addView(imageViewList.get(position ％ imageViewList.size()));
  return imageViewList.get(position ％ imageViewList.size());
 }
}

@Override
public void onPageScrollStateChanged(int arg0) {
 // TODO Auto-generated method stub

}

@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
 // TODO Auto-generated method stub

}

/**
 * 当viewpager页面切换时回调
 * @param position 就是当前显示的page页
 */
@Override
public void onPageSelected(int position) {
 tvImageDescription.setText(imageDescriptions[position ％ imageViewList.size()]);
 llPointGroup.getChildAt(position ％ imageViewList.size()).setEnabled(true);
 llPointGroup.getChildAt(previousPosition).setEnabled(false);

previousPosition = position ％ imageViewList.size();
}
}