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 }
