Android应用中利用ViewPager实现多页面滑动切换效果示例

1、添加android support包
因为上面的几个类都是在android support包中才提供，我们先添加包。
在Eclipse->Window->Android SDK Manager，选择列表中Extras->Android Support Library进行安装。下载完后在android-sdk\extras\android\support目录下，这里我们选择v4版本，进入v4目录，拷贝其中的android-support-v4.jar文件到工程的libs目录(若没有新建)下即可，编译时ADT会自动将其导入项目中。

2、新建ViewPager的layout，内容如下

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical" >
  
  <android.support.v4.view.ViewPager
    android:id="@+id/viewPager"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center" >
    <android.support.v4.view.PagerTabStrip  
      android:layout_width="wrap_content"  
      android:layout_height="wrap_content"  
      android:layout_gravity="top" />
  </android.support.v4.view.ViewPager>
</LinearLayout>

ViewPager用来管理layout并可以左右滑动显示各个页面数据，PagerTabStrip用来显示页面title，android:layout_gravity="top"表示title在顶部，可设置bottom等。

3、新建FragmentActivity页面
FragmentActivity页面含有ViewPager元素，可以用来显示Fragment，定义如下：

public class ViewPagerDemo extends FragmentActivity {

  /** 页面list **/
  List<Fragment> fragmentList = new ArrayList<Fragment>();
  /** 页面title list **/
  List<String>  titleList  = new ArrayList<String>();

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.view_pager_demo);

    ViewPager vp = (ViewPager)findViewById(R.id.viewPager);
    fragmentList.add(new ViewPagerFragment1("页面1"));
    fragmentList.add(new ViewPagerFragment1("页面2"));
    fragmentList.add(new ViewPagerFragment1("页面3"));
    titleList.add("title 1 ");
    titleList.add("title 2 ");
    titleList.add("title 3 ");
    vp.setAdapter(new myPagerAdapter(getSupportFragmentManager(), fragmentList, titleList));
  }

  /**
   * 定义适配器
   */
  class myPagerAdapter extends FragmentPagerAdapter {

    private List<Fragment> fragmentList;
    private List<String>  titleList;

    public myPagerAdapter(FragmentManager fm, List<Fragment> fragmentList, List<String> titleList){
      super(fm);
      this.fragmentList = fragmentList;
      this.titleList = titleList;
    }

    /**
     * 得到每个页面
     */
    @Override
    public Fragment getItem(int arg0) {
      return (fragmentList == null || fragmentList.size() == 0) ? null : fragmentList.get(arg0);
    }

    /**
     * 每个页面的title
     */
    @Override
    public CharSequence getPageTitle(int position) {
      return (titleList.size() > position) ? titleList.get(position) : "";
    }

    /**
     * 页面的总个数
     */
    @Override
    public int getCount() {
      return fragmentList == null ? 0 : fragmentList.size();
    }
  }
}

其中的myPagerAdapter集成自ragmentPagerAdapter，为ViewPager提供数据源。

onCreate函数得到ViewPager实例并设置数据源，getSupportFragmentManager表示得到Fragment管理器。ViewPagerFragment1表示具体的页面，见下面介绍。

4、新建Fragment页面
Fragment页面即为左右滑动需要显示的页面，新建类集成Fragment，并重写onCreateView函数即可。onCreateView函数相当于Activity的onCreate函数。如下：

public class ViewPagerFragment1 extends Fragment {

  private String  text;
  private TextView tv = null;

  public ViewPagerFragment1(String text){
    super();
    this.text = text;
  }

  /**
   * 覆盖此函数，先通过inflater inflate函数得到view最后返回
   */
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.view_pager_fragment_demo1, container, false);
    tv = (TextView)v.findViewById(R.id.viewPagerText);
    tv.setText(text);
    return v;
  }
}

5、示例工程代码：

package cn.trinea.android.demo;

import java.util.ArrayList;
import java.util.List;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;

public class ViewPagerDemo extends BaseFragmentActivity {

  private static int TOTAL_COUNT = 3;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState, R.layout.view_pager_demo);

    ViewPager vp = (ViewPager)findViewById(R.id.view_pager);
    List<Fragment> fragmentList = new ArrayList<Fragment>();
    List<String> titleList = new ArrayList<String>();
    for (int i = 0; i < TOTAL_COUNT; i++) {
      ViewPagerFragment viewPagerFragment1 = new ViewPagerFragment();
      Bundle bundle = new Bundle();
      bundle.putInt("upImageId", 0);
      bundle.putString("text", "Page " + i);
      viewPagerFragment1.setArguments(bundle);
      titleList.add("title " + i);
      fragmentList.add(viewPagerFragment1);
    }

    vp.setAdapter(new myPagerAdapter(getSupportFragmentManager(), fragmentList, titleList));

  }

  class myPagerAdapter extends FragmentPagerAdapter {

    private List<Fragment> fragmentList;
    private List<String>  titleList;

    public myPagerAdapter(FragmentManager fm, List<Fragment> fragmentList, List<String> titleList) {
      super(fm);
      this.fragmentList = fragmentList;
      this.titleList = titleList;
    }

    @Override
    public Fragment getItem(int arg0) {
      return (fragmentList == null || fragmentList.size() == 0) ? null : fragmentList.get(arg0);
    }

    @Override
    public CharSequence getPageTitle(int position) {
      return (titleList.size() > position) ? titleList.get(position) : "";
    }

    @Override
    public int getCount() {
      return fragmentList == null ? 0 : fragmentList.size();
    }
  }
}

简单效果如下：