Android應用中利用ViewPager實現多頁面滑動切換效果示例

1、添加android support包
因為上面的幾個類都是在android support包中才提供，我們先添加包。
在Eclipse->Window->Android SDK Manager，選擇列表中Extras->Android Support Library進行安裝。下載完後在android-sdk\extras\android\support目錄下，這裡我們選擇v4版本，進入v4目錄，拷貝其中的android-support-v4.jar文件到工程的libs目錄(若沒有新建)下即可，編譯時ADT會自動將其導入項目中。

2、新建ViewPager的layout，內容如下

<?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用來管理layout並可以左右滑動顯示各個頁面數據，PagerTabStrip用來顯示頁面title，android:layout_gravity="top"表示title在頂部，可設置bottom等。

3、新建FragmentActivity頁面
FragmentActivity頁面含有ViewPager元素，可以用來顯示Fragment，定義如下：

public class ViewPagerDemo extends FragmentActivity {

  /** 頁面list **/
  List<Fragment> fragmentList = new ArrayList<Fragment>();
  /** 頁面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("頁面1"));
    fragmentList.add(new ViewPagerFragment1("頁面2"));
    fragmentList.add(new ViewPagerFragment1("頁面3"));
    titleList.add("title 1 ");
    titleList.add("title 2 ");
    titleList.add("title 3 ");
    vp.setAdapter(new myPagerAdapter(getSupportFragmentManager(), fragmentList, titleList));
  }

  /**
   * 定義適配器
   */
  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;
    }

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

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

    /**
     * 頁面的總個數
     */
    @Override
    public int getCount() {
      return fragmentList == null ? 0 : fragmentList.size();
    }
  }
}

其中的myPagerAdapter集成自ragmentPagerAdapter，為ViewPager提供數據源。

onCreate函數得到ViewPager實例並設置數據源，getSupportFragmentManager表示得到Fragment管理器。ViewPagerFragment1表示具體的頁面，見下面介紹。

4、新建Fragment頁面
Fragment頁面即為左右滑動需要顯示的頁面，新建類集成Fragment，並重寫onCreateView函數即可。onCreateView函數相當於Activity的onCreate函數。如下：

public class ViewPagerFragment1 extends Fragment {

  private String  text;
  private TextView tv = null;

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

  /**
   * 覆蓋此函數，先通過inflater inflate函數得到view最後返回
   */
  @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、示例工程代碼：

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();
    }
  }
}

簡單效果如下：