viewpage广告条的制作

 package com.itheima27.viewpagerdemo;

 import java.util.ArrayList;

 import java.util.List;

 import android.app.Activity;

 import android.os.Bundle;

 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.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 {

     private List<ImageView> imageViewList;

     private TextView tvDescription;

     private LinearLayout llPointGroup;

     private int previousEnabledPosition = 0;        // 前一个被选中的"点"的索引, 默认情况下: 0

     private String[] imageDescriptionArray = {

             "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 ViewPager mViewPager;

     private boolean isStop = false;        // 是否停止子线程, 不会停止

     @Override

     protected void onDestroy() {

         isStop = true;

         super.onDestroy();

     }

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.activity_main);

         init();

         // 开启线程无限自动移动

         Thread mThread = new Thread(new Runnable() {

             @Override

             public void run() {

                 while(!isStop) {

                     // 每隔2秒钟, 发送一条消息到主线程, 更新viewpager的界面

                     SystemClock.sleep(2000);

                     runOnUiThread(new Runnable() {

                         @Override

                         public void run() {

                             // 此方法是在主线程中执行

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

                         }

                     });

                 }

             }

         });

         mThread.start();

     }

     private void init() {

         mViewPager = (ViewPager) findViewById(R.id.viewpager);

         llPointGroup = (LinearLayout) findViewById(R.id.ll_point_group);

         tvDescription = (TextView) findViewById(R.id.tv_image_description);

         imageViewList = new ArrayList<ImageView>();

         int[] imageResIDs = {

                 R.drawable.a,

                 R.drawable.b,

                 R.drawable.c,

                 R.drawable.d,

                 R.drawable.e

         };

         ImageView iv;

         View view;

         LayoutParams params;

         for (int id : imageResIDs) {

             iv = new ImageView(this);

             iv.setBackgroundResource(id);

             imageViewList.add(iv);

             // 每循环一次, 添加一个点到Linearlayout中

             view = new View(this);

             view.setBackgroundResource(R.drawable.point_background);

             params = new LayoutParams(5, 5);

             params.leftMargin = 5;

             view.setEnabled(false);

             view.setLayoutParams(params);

             llPointGroup.addView(view);        // 向线性布局中添加"点"

         }

         mViewPager.setAdapter(new MyAdapter());

         mViewPager.setOnPageChangeListener(this);

         // 初始化图片描述, 和哪一个点被选中

 //        tvDescription.setText(imageDescriptionArray[0]);

 //        llPointGroup.getChildAt(0).setEnabled(true);

         // 初始化ViewPager的默认position为Integer.Max_value的一半

         int index = (Integer.MAX_VALUE / 2) - (Integer.MAX_VALUE / 2 % imageViewList.size());

         mViewPager.setCurrentItem(index);        // 设置当前viewpager选中的pager页, 会触发OnPageChangeListener.onPagerSelected

     }

     class MyAdapter extends PagerAdapter {

         @Override

         public int getCount() {

             return Integer.MAX_VALUE;

         }

         /**

          * 复用对象.

          * true 复用对象

          * false 用的是object

          */

         @Override

         public boolean isViewFromObject(View arg0, Object arg1) {

             return arg0 == arg1;

         }

         /**

          * 销毁对象

          * @param position 将要被销毁对象的索引位置

          */

         @Override

         public void destroyItem(ViewGroup container, int position, Object object) {

             container.removeView(imageViewList.get(position % imageViewList.size()));

         }

         /**

          * 初始化一个view对象

          * @param position 将要被创建的对象的索引位置

          */

         @Override

         public Object instantiateItem(ViewGroup container, int position) {

             // 先把对象添加到viewpager中, 再返回当前对象

             container.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

     }

     @Override

     public void onPageSelected(int position) {

         // 取余后的索引

         int newPosition = position % imageViewList.size();

         // 根据索引设置图片的描述

         tvDescription.setText(imageDescriptionArray[newPosition]);

         // 把上一个点设置为未选中

         llPointGroup.getChildAt(previousEnabledPosition).setEnabled(false);

         // 根据索引设置哪一个点被选中

         llPointGroup.getChildAt(newPosition).setEnabled(true);

         previousEnabledPosition = newPosition;

     }

 }