运用ViewPager实现高仿launcher拖动效果

使用ViewPager实现高仿launcher拖动效果

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?前面一篇高仿launcher和墨迹左右拖动效果获得了很多朋友的好评，上一篇文章 主要是通过自定义ViewGroup实现的，有点麻烦。今天用ViewPager 这个类实现了同样的效果，这样代码更少，但是效果是一样的。ViewPager是实现左右两个屏幕平滑地切换的一个类，它是Google提供的。

?????? 使用ViewPager首先需要引入android-support-v4.jar这个jar包。具体ViewPager的用法，这里不做介绍，自己从网上搜索吧！

?????? 下面先看一下效果：

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效果请自行体验和上一篇比较。下面上代码：

首先是layout下面的main.xml

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[html]?view plaincopy

1. <?xml?version="1.0"?encoding="utf-8"?>??
2. <FrameLayout?xmlns:android="http://schemas.android.com/apk/res/android"??
3. ????android:layout_width="fill_parent"??
4. ????android:layout_height="fill_parent"??
5. ????android:orientation="vertical"?>??
6. ??
7. ????<android.support.v4.view.ViewPager??
8. ????????android:id="@+id/viewPager"??
9. ????????android:layout_width="fill_parent"??
10. ????????android:layout_height="wrap_content"?/>??
11. ??
12. ????<RelativeLayout??
13. ????????android:layout_width="fill_parent"??
14. ????????android:layout_height="wrap_content"??
15. ????????android:orientation="vertical"?>??
16. ??
17. ????????<LinearLayout??
18. ????????????android:id="@+id/viewGroup"??
19. ????????????android:layout_width="fill_parent"??
20. ????????????android:layout_height="wrap_content"??
21. ????????????android:layout_alignParentBottom="true"??
22. ????????????android:layout_marginBottom="30dp"??
23. ????????????android:gravity="center_horizontal"??
24. ????????????android:orientation="horizontal"?>??
25. ????????</LinearLayout>??
26. ????</RelativeLayout>??
27. ??
28. </FrameLayout>??

接下来为每一个切换界面设置布局item1.xml

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[html]?view plaincopy

1. <?xml?version="1.0"?encoding="UTF-8"?>??
2. <LinearLayout?xmlns:android="http://schemas.android.com/apk/res/android"??
3. ????android:layout_width="fill_parent"??
4. ????android:layout_height="fill_parent"??
5. ????android:orientation="vertical"?>??
6. ??
7. ????<ImageView??
8. ????????android:layout_width="fill_parent"??
9. ????????android:layout_height="fill_parent"??
10. ????????android:background="@drawable/guide01"?>??
11. ????</ImageView>??
12. ??
13. </LinearLayout>??

其他的几个界面布局和这个一样 ，就是修改下背景图片，所以不再复述，

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最后是核心代码：

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[html]?view plaincopy

1. import?java.util.ArrayList;??
2. ??
3. ??
4. import?android.app.Activity;??
5. import?android.os.Bundle;??
6. import?android.os.Parcelable;??
7. import?android.support.v4.view.PagerAdapter;??
8. import?android.support.v4.view.ViewPager;??
9. import?android.support.v4.view.ViewPager.OnPageChangeListener;??
10. import?android.view.LayoutInflater;??
11. import?android.view.View;??
12. import?android.view.ViewGroup;??
13. import?android.view.ViewGroup.LayoutParams;??
14. import?android.view.Window;??
15. import?android.widget.ImageView;??
16. ??
17. public?class?MainActivity?extends?Activity?{??
18. ????ViewPager?viewPager;??
19. ????ArrayList<View>?list;??
20. ????ViewGroup?main,?group;??
21. ????ImageView?imageView;??
22. ????ImageView[]?imageViews;??
23. ??
24. ????@Override??
25. ????public?void?onCreate(Bundle?savedInstanceState)?{??
26. ????????super.onCreate(savedInstanceState);??
27. ????????this.requestWindowFeature(Window.FEATURE_NO_TITLE);??
28. ????????LayoutInflater?inflater?=?getLayoutInflater();??
29. ????????list?=?new?ArrayList<View>();??
30. ????????list.add(inflater.inflate(R.layout.item1,?null));??
31. ????????list.add(inflater.inflate(R.layout.item2,?null));??
32. ????????list.add(inflater.inflate(R.layout.item3,?null));??
33. ????????list.add(inflater.inflate(R.layout.item4,?null));??
34. ????????list.add(inflater.inflate(R.layout.item5,?null));??
35. ??
36. ????????imageViews?=?new?ImageView[list.size()];??
37. ????????ViewGroup?main?=?(ViewGroup)?inflater.inflate(R.layout.main,?null);??
38. ????????//?group是R.layou.main中的负责包裹小圆点的LinearLayout.??
39. ????????ViewGroup?group?=?(ViewGroup)?main.findViewById(R.id.viewGroup);??
40. ??
41. ????????viewPager?=?(ViewPager)?main.findViewById(R.id.viewPager);??
42. ??
43. ????????for?(int?i?=?0;?i?<?list.size();?i++)?{??
44. ????????????imageView?=?new?ImageView(MainActivity.this);??
45. ????????????imageView.setLayoutParams(new?LayoutParams(10,10));??
46. ????????????imageView.setPadding(10,?0,?10,?0);??
47. ????????????imageViews[i]?=?imageView;??
48. ????????????if?(i?==?0)?{??
49. ????????????????//?默认进入程序后第一张图片被选中;??
50. ????????????????imageViews[i].setBackgroundResource(R.drawable.guide_dot_white);??
51. ????????????}?else?{??
52. ????????????????imageViews[i].setBackgroundResource(R.drawable.guide_dot_black);??
53. ????????????}??
54. ????????????group.addView(imageView);??
55. ????????}??
56. ??
57. ????????setContentView(main);??
58. ??
59. ????????viewPager.setAdapter(new?MyAdapter());??
60. ????????viewPager.setOnPageChangeListener(new?MyListener());??
61. ????}??
62. ??
63. ????class?MyAdapter?extends?PagerAdapter?{??
64. ??
65. ????????@Override??
66. ????????public?int?getCount()?{??
67. ????????????return?list.size();??
68. ????????}??
69. ??
70. ????????@Override??
71. ????????public?boolean?isViewFromObject(View?arg0,?Object?arg1)?{??
72. ????????????return?arg0?==?arg1;??
73. ????????}??
74. ??
75. ????????@Override??
76. ????????public?int?getItemPosition(Object?object)?{??
77. ????????????//?TODO?Auto-generated?method?stub??
78. ????????????return?super.getItemPosition(object);??
79. ????????}??
80. ??
81. ????????@Override??
82. ????????public?void?destroyItem(View?arg0,?int?arg1,?Object?arg2)?{??
83. ????????????//?TODO?Auto-generated?method?stub??
84. ????????????((ViewPager)?arg0).removeView(list.get(arg1));??
85. ????????}??
86. ??
87. ????????@Override??
88. ????????public?Object?instantiateItem(View?arg0,?int?arg1)?{??
89. ????????????//?TODO?Auto-generated?method?stub??
90. ????????????((ViewPager)?arg0).addView(list.get(arg1));??
91. ????????????return?list.get(arg1);??
92. ????????}??
93. ??
94. ????????@Override??
95. ????????public?void?restoreState(Parcelable?arg0,?ClassLoader?arg1)?{??
96. ????????????//?TODO?Auto-generated?method?stub??
97. ??
98. ????????}??
99. ??
100. ????????@Override??
101. ????????public?Parcelable?saveState()?{??
102. ????????????//?TODO?Auto-generated?method?stub??
103. ????????????return?null;??
104. ????????}??
105. ??
106. ????????@Override??
107. ????????public?void?startUpdate(View?arg0)?{??
108. ????????????//?TODO?Auto-generated?method?stub??
109. ??
110. ????????}??
111. ??
112. ????????@Override??
113. ????????public?void?finishUpdate(View?arg0)?{??
114. ????????????//?TODO?Auto-generated?method?stub??
115. ??
116. ????????}??
117. ????}??
118. ??
119. ????class?MyListener?implements?OnPageChangeListener?{??
120. ??
121. ????????@Override??
122. ????????public?void?onPageScrollStateChanged(int?arg0)?{??
123. ????????????//?TODO?Auto-generated?method?stub??
124. ??
125. ????????}??
126. ??
127. ????????@Override??
128. ????????public?void?onPageScrolled(int?arg0,?float?arg1,?int?arg2)?{??
129. ????????????//?TODO?Auto-generated?method?stub??
130. ??
131. ????????}??
132. ??
133. ????????@Override??
134. ????????public?void?onPageSelected(int?arg0)?{??
135. ????????????for?(int?i?=?0;?i?<?imageViews.length;?i++)?{??
136. ????????????????imageViews[arg0]??
137. ????????????????????????.setBackgroundResource(R.drawable.guide_dot_white);??
138. ????????????????if?(arg0?!=?i)?{??
139. ????????????????????imageViews[i]??
140. ????????????????????????????.setBackgroundResource(R.drawable.guide_dot_black);??
141. ????????????????}??
142. ????????????}??
143. ??
144. ????????}??
145. ??
146. ????}??
147. }??

最后在提醒一句，不要忘记加入android-support-v4.jar这个jar包。

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