Android:实现滑屏

先看效果，就是左右滑屏的效果

具体实现详解

android compatibility package, revision 3在7月份发布后，其中有个ViewPager引起了我的注意

官方的描述：

 请参考：http://developer.android.com/sdk/compatibility-library.html#Notes

ViewPager的下载与安装

首先通过SDK Manager更新最新版android compatibility package, revision 3

更新后，在eclipse中工程上点击右键，选择android tools -> add compatibility library即可完成安装

实际上就是一个jar包，手工导到工程中也可

jar包所在位置是\android-sdk\extras\android\compatibility\v4\android-support-v4.jar

至此准备环境已经ok

下边还是通过代码进行说话吧

准备布局文件

viewpager_layout.xml

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" android:orientation="vertical">
5 <!-- 此处需要给出全路径 -->
6 <android.support.v4.view.ViewPager
7     android:id="@+id/viewpagerLayout" android:layout_height="fill_parent" android:layout_width="fill_parent"/>
8 </LinearLayout>

layout1.xml

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" android:orientation="vertical">
5     <TextView android:textAppearance="?android:attr/textAppearanceLarge" android:layout_height="wrap_content" android:id="@+id/textView1" android:layout_width="fill_parent" android:text="第一页"></TextView>
6     <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/editText1">
7         <requestFocus></requestFocus>
8     </EditText>
9 </LinearLayout>

layout2.xml

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" android:orientation="vertical">
5     <TextView android:textAppearance="?android:attr/textAppearanceLarge" android:layout_height="wrap_content" android:id="@+id/textView1" android:layout_width="fill_parent" android:text="第二页"></TextView>
6     <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/editText1">
7         <requestFocus></requestFocus>
8     </EditText>
9 </LinearLayout>

layout3.xml

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" android:orientation="vertical">
5     <TextView android:textAppearance="?android:attr/textAppearanceLarge" android:layout_height="wrap_content" android:id="@+id/textView1" android:layout_width="fill_parent" android:text="第三页"></TextView>
6     <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/editText1">
7         <requestFocus></requestFocus>
8     </EditText>
9 </LinearLayout>

主程序

001 package a.b;
002
003 import java.util.ArrayList;
004 import java.util.List;
005
006 import android.app.Activity;
007 import android.os.Bundle;
008 import android.os.Parcelable;
009 import android.support.v4.view.PagerAdapter;
010 import android.support.v4.view.ViewPager;
011 import android.support.v4.view.ViewPager.OnPageChangeListener;
012 import android.util.Log;
013 import android.view.LayoutInflater;
014 import android.view.View;
015 import android.widget.EditText;
016
017 public class TestViewPager extends Activity {
018     private ViewPager myViewPager;
019
020     private MyPagerAdapter myAdapter;
021
022     private LayoutInflater mInflater;
023     private List<View> mListViews;
024     private View layout1 = null;
025     private View layout2 = null;
026     private View layout3 = null;
027
028     @Override
029     protected void onCreate(Bundle savedInstanceState) {
030         super.onCreate(savedInstanceState);
031         setContentView(R.layout.viewpager_layout);
032         myAdapter = new MyPagerAdapter();
033         myViewPager = (ViewPager) findViewById(R.id.viewpagerLayout);
034         myViewPager.setAdapter(myAdapter);
035
036         mListViews = new ArrayList<View>();
037         mInflater = getLayoutInflater();
038         layout1 = mInflater.inflate(R.layout.layout1, null);
039         layout2 = mInflater.inflate(R.layout.layout2, null);
040         layout3 = mInflater.inflate(R.layout.layout3, null);
041
042         mListViews.add(layout1);
043         mListViews.add(layout2);
044         mListViews.add(layout3);
045
046         //初始化当前显示的view
047         myViewPager.setCurrentItem(1);
048
049         //初始化第二个view的信息
050         EditText v2EditText = (EditText)layout2.findViewById(R.id.editText1);
051         v2EditText.setText("动态设置第二个view的值");
052
053         myViewPager.setOnPageChangeListener(new OnPageChangeListener() {
054
055             @Override
056             public void onPageSelected(int arg0) {
057                 Log.d("k", "onPageSelected - " + arg0);
058                 //activity从1到2滑动，2被加载后掉用此方法
059                 View v = mListViews.get(arg0);
060                 EditText editText = (EditText)v.findViewById(R.id.editText1);
061                 editText.setText("动态设置#"+arg0+"edittext控件的值");
062             }
063
064             @Override
065             public void onPageScrolled(int arg0, float arg1, int arg2) {
066                 Log.d("k", "onPageScrolled - " + arg0);
067                 //从1到2滑动，在1滑动前调用
068             }
069
070             @Override
071             public void onPageScrollStateChanged(int arg0) {
072                 Log.d("k", "onPageScrollStateChanged - " + arg0);
073                 //状态有三个0空闲，1是增在滑行中，2目标加载完毕
074                 /**
075                  * Indicates that the pager is in an idle, settled state. The current page
076                  * is fully in view and no animation is in progress.
077                  */
078                 //public static final int SCROLL_STATE_IDLE = 0;
079                 /**
080                  * Indicates that the pager is currently being dragged by the user.
081                  */
082                 //public static final int SCROLL_STATE_DRAGGING = 1;
083                 /**
084                  * Indicates that the pager is in the process of settling to a final position.
085                  */
086                 //public static final int SCROLL_STATE_SETTLING = 2;
087
088             }
089         });
090
091     }
092
093     private class MyPagerAdapter extends PagerAdapter{
094
095         @Override
096         public void destroyItem(View arg0, int arg1, Object arg2) {
097             Log.d("k", "destroyItem");
098             ((ViewPager) arg0).removeView(mListViews.get(arg1));
099         }
100
101         @Override
102         public void finishUpdate(View arg0) {
103             Log.d("k", "finishUpdate");
104         }
105
106         @Override
107         public int getCount() {
108             Log.d("k", "getCount");
109             return mListViews.size();
110         }
111
112         @Override
113         public Object instantiateItem(View arg0, int arg1) {
114             Log.d("k", "instantiateItem");
115             ((ViewPager) arg0).addView(mListViews.get(arg1),0);
116             return mListViews.get(arg1);
117         }
118
119         @Override
120         public boolean isViewFromObject(View arg0, Object arg1) {
121             Log.d("k", "isViewFromObject");
122             return arg0==(arg1);
123         }
124
125         @Override
126         public void restoreState(Parcelable arg0, ClassLoader arg1) {
127             Log.d("k", "restoreState");
128         }
129
130         @Override
131         public Parcelable saveState() {
132             Log.d("k", "saveState");
133             return null;
134         }
135
136         @Override
137         public void startUpdate(View arg0) {
138             Log.d("k", "startUpdate");
139         }
140
141     }
142
143 }

在实机上测试后，非常流畅，这也就是说官方版的左右滑屏控件已经实现

目前，关于viewpager的文章非常少，本文是通过阅读viewpager源代码分析出的写法

当然此文章仅是抛砖引玉，而且属于框架式程序，目的就是让读者了解API的基本用法

希望这篇原创文章对大家有帮助

欢迎感兴趣的朋友一起讨论

共同学习，共同进步

另外，ViewPager的注释上有这么一段话，大体意思是该控件目前属于早期实现，后续会有修改

01 /**
02  * Layout manager that allows the user to flip left and right
03  * through pages of data.  You supply an implementation of a
04  * {@link PagerAdapter} to generate the pages that the view shows.
05  *
06  * <p>Note this class is currently under early design and
07  * development.  The API will likely change in later updates of
08  * the compatibility library, requiring changes to the source code
09  * of apps when they are compiled against the newer version.</p>
10  */