Android实现广告图片轮播效果

MainActivity.java

package com.xuliugen.viewpager;

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
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.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends Activity {

  private ViewPager viewPager;

  private LinearLayout pointGroup;

  private TextView iamgeDesc;

  // 图片资源ID
  private final int[] imageIds = { R.drawable.a, R.drawable.b, R.drawable.c,
      R.drawable.d, R.drawable.e };

  // 图片标题集合
  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", "热血屌丝的反杀" };

  private ArrayList<ImageView> imageList;

  /**
   * 上一个页面的位置
   */
  protected int lastPosition;

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

    viewPager = (ViewPager) findViewById(R.id.viewpager);
    pointGroup = (LinearLayout) findViewById(R.id.point_group);
    iamgeDesc = (TextView) findViewById(R.id.image_desc);
    iamgeDesc.setText(imageDescriptions[0]);

    imageList = new ArrayList<ImageView>();
    for (int i = 0; i < imageIds.length; i++) {

      // 初始化图片资源
      ImageView image = new ImageView(this);
      image.setBackgroundResource(imageIds[i]);
      imageList.add(image);

      // 添加指示点
      ImageView point = new ImageView(this);
      LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
          LinearLayout.LayoutParams.WRAP_CONTENT,
          LinearLayout.LayoutParams.WRAP_CONTENT);

      params.rightMargin = 20;
      point.setLayoutParams(params);

      point.setBackgroundResource(R.drawable.point_bg);
      if (i == 0) {
        point.setEnabled(true);
      } else {
        point.setEnabled(false);
      }
      pointGroup.addView(point);
    }

    viewPager.setAdapter(new MyPagerAdapter());

    // viewPager.setCurrentItem(Integer.MAX_VALUE/2 -
    // (Integer.MAX_VALUE/2%imageList.size())) ;

    viewPager.setOnPageChangeListener(new OnPageChangeListener() {

      @Override
      /**
       * 页面切换后调用 
       * position 新的页面位置
       */
      public void onPageSelected(int position) {

        position = position % imageList.size();

        // 设置文字描述内容
        iamgeDesc.setText(imageDescriptions[position]);

        // 改变指示点的状态
        // 把当前点enbale 为true
        pointGroup.getChildAt(position).setEnabled(true);
        // 把上一个点设为false
        pointGroup.getChildAt(lastPosition).setEnabled(false);
        lastPosition = position;

      }

      @Override
      /**
       * 页面正在滑动的时候，回调
       */
      public void onPageScrolled(int position, float positionOffset,
          int positionOffsetPixels) {
      }

      @Override
      /**
       * 当页面状态发生变化的时候，回调
       */
      public void onPageScrollStateChanged(int state) {

      }
    });

    /*
     * 自动循环： 1、定时器：Timer 2、开子线程 while true 循环 3、ColckManager 4、 用handler
     * 发送延时信息，实现循环
     */
    isRunning = true;
    // 设置图片的自动滑动
    handler.sendEmptyMessageDelayed(0, 3000);
  }

  /**
   * 判断是否自动滚动
   */
  private boolean isRunning = false;

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

      // 让viewPager 滑动到下一页
      viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
      if (isRunning) {
        handler.sendEmptyMessageDelayed(0, 3000);
      }
    };
  };

  protected void onDestroy() {

    isRunning = false;
  };

  private class MyPagerAdapter extends PagerAdapter {

    @Override
    /**
     * 获得页面的总数
     */
    public int getCount() {
      return Integer.MAX_VALUE; // 使得图片可以循环
    }

    @Override
    /**
     * 获得相应位置上的view
     * container view的容器，其实就是viewpager自身
     * position   相应的位置
     */
    public Object instantiateItem(ViewGroup container, int position) {

      // System.out.println("instantiateItem ::" + position);

      // 给 container 添加一个view
      container.addView(imageList.get(position % imageList.size()));
      // 返回一个和该view相对的object
      return imageList.get(position % imageList.size());
    }

    @Override
    /**
     * 判断 view和object的对应关系 
     */
    public boolean isViewFromObject(View view, Object object) {
      if (view == object) {
        return true;
      } else {
        return false;
      }
    }

    @Override
    /**
     * 销毁对应位置上的object
     */
    public void destroyItem(ViewGroup container, int position, Object object) {
      // System.out.println("destroyItem ::" + position);

      container.removeView((View) object);
      object = null;
    }
  }

}

								 
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