viewpage广告条的制作

 

  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<ImageView> 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<ImageView>();

 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.onPagerSelected

118         

119     }

120 

121     class MyAdapter extends PagerAdapter {

122 

123         @Override

124         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object

132          */

133         @Override

134         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         @Override

143         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         @Override

152         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     @Override

160     public void onPageScrollStateChanged(int arg0) {

161         // TODO Auto-generated method stub

162         

163     }

164 

165     @Override

166     public void onPageScrolled(int arg0, float arg1, int arg2) {

167         // TODO Auto-generated method stub

168         

169     }

170 

171     @Override

172     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 }

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