1 package com.itheima27.viewpagerdemo;  2   3 import java.util.ArrayList;  4 import java.util.List;  5   6 import android.app.Activity;  7 import android.os.Bundle;  8 import android.os.SystemClock;  9 import android.support.v4.view.PagerAdapter; 10 import android.support.v4.view.ViewPager; 11 import android.support.v4.view.ViewPager.OnPageChangeListener; 12 import android.view.View; 13 import android.view.ViewGroup; 14 import android.widget.ImageView; 15 import android.widget.LinearLayout; 16 import android.widget.LinearLayout.LayoutParams; 17 import android.widget.TextView; 18  19 public class MainActivity extends Activity implements OnPageChangeListener { 20  21     private List
      
        imageViewList; 22     private TextView tvDescription; 23     private LinearLayout llPointGroup; 24     private int previousEnabledPosition = 0;        // 前一个被选中的"点"的索引, 默认情况下: 0 25      26     private String[] imageDescriptionArray = { 27             "巩俐不低俗，我就不能低俗", 28             "扑树又回来啦！再唱经典老歌引万人大合唱", 29             "揭秘北京电影如何升级", 30             "乐视网TV版大派送", 31             "热血屌丝的反杀" 32     }; 33     private ViewPager mViewPager; 34      35     private boolean isStop = false;        // 是否停止子线程, 不会停止 36      37  38     @Override 39     protected void onDestroy() { 40         isStop = true; 41         super.onDestroy(); 42     } 43  44     @Override 45     protected void onCreate(Bundle savedInstanceState) { 46         super.onCreate(savedInstanceState); 47         setContentView(R.layout.activity_main); 48          49         init(); 50          51         // 开启线程无限自动移动 52         Thread mThread = new Thread(new Runnable() { 53             @Override 54             public void run() { 55                 while(!isStop) { 56                     // 每隔2秒钟, 发送一条消息到主线程, 更新viewpager的界面 57                     SystemClock.sleep(2000); 58                      59                     runOnUiThread(new Runnable() { 60                         @Override 61                         public void run() { 62                             // 此方法是在主线程中执行 63                             mViewPager.setCurrentItem(mViewPager.getCurrentItem() + 1); 64                         } 65                     }); 66                 } 67             } 68         }); 69         mThread.start(); 70     } 71  72     private void init() { 73         mViewPager = (ViewPager) findViewById(R.id.viewpager); 74         llPointGroup = (LinearLayout) findViewById(R.id.ll_point_group); 75         tvDescription = (TextView) findViewById(R.id.tv_image_description); 76          77         imageViewList = new ArrayList
       
        (); 78          79         int[] imageResIDs = { 80                 R.drawable.a, 81                 R.drawable.b, 82                 R.drawable.c, 83                 R.drawable.d, 84                 R.drawable.e 85         }; 86          87         ImageView iv; 88         View view; 89         LayoutParams params; 90         for (int id : imageResIDs) { 91             iv = new ImageView(this); 92             iv.setBackgroundResource(id); 93             imageViewList.add(iv); 94              95              96             // 每循环一次, 添加一个点到Linearlayout中 97             view = new View(this); 98             view.setBackgroundResource(R.drawable.point_background); 99             params = new LayoutParams(5, 5);100             params.leftMargin = 5;101             view.setEnabled(false);102             view.setLayoutParams(params);103             104             llPointGroup.addView(view);        // 向线性布局中添加"点"105         }106         107         mViewPager.setAdapter(new MyAdapter());108         mViewPager.setOnPageChangeListener(this);109         110         // 初始化图片描述, 和哪一个点被选中111 //        tvDescription.setText(imageDescriptionArray[0]);112 //        llPointGroup.getChildAt(0).setEnabled(true);113         114         115         // 初始化ViewPager的默认position为Integer.Max_value的一半116         int index = (Integer.MAX_VALUE / 2) - (Integer.MAX_VALUE / 2 % imageViewList.size());117         mViewPager.setCurrentItem(index);        // 设置当前viewpager选中的pager页, 会触发OnPageChangeListener.onPagerSelected118         119     }120 121     class MyAdapter extends PagerAdapter {122 123         @Override124         public int getCount() {125             return Integer.MAX_VALUE;126         }127 128         /**129          * 复用对象.130          * true 复用对象131          * false 用的是object132          */133         @Override134         public boolean isViewFromObject(View arg0, Object arg1) {135             return arg0 == arg1;136         }137 138         /**139          * 销毁对象140          * @param position 将要被销毁对象的索引位置141          */142         @Override143         public void destroyItem(ViewGroup container, int position, Object object) {144             container.removeView(imageViewList.get(position % imageViewList.size()));145         }146 147         /**148          * 初始化一个view对象149          * @param position 将要被创建的对象的索引位置150          */151         @Override152         public Object instantiateItem(ViewGroup container, int position) {153             // 先把对象添加到viewpager中, 再返回当前对象154             container.addView(imageViewList.get(position % imageViewList.size()));155             return imageViewList.get(position % imageViewList.size());156         }157     }158 159     @Override160     public void onPageScrollStateChanged(int arg0) {161         // TODO Auto-generated method stub162         163     }164 165     @Override166     public void onPageScrolled(int arg0, float arg1, int arg2) {167         // TODO Auto-generated method stub168         169     }170 171     @Override172     public void onPageSelected(int position) {173         174         // 取余后的索引175         int newPosition = position % imageViewList.size();176         177         // 根据索引设置图片的描述178         tvDescription.setText(imageDescriptionArray[newPosition]);179         180         // 把上一个点设置为未选中181         llPointGroup.getChildAt(previousEnabledPosition).setEnabled(false);182         183         // 根据索引设置哪一个点被选中184         llPointGroup.getChildAt(newPosition).setEnabled(true);185         186         previousEnabledPosition = newPosition;187     }188 }