实例讲解Android中ViewPager组件的一些进阶使用技巧

我们经常看到使用了ViewPager的App，在每页上面都会有一个滑块来标志当前处于哪一页。在PagerView包里有android.support.v4.view.PagerTitleStrip和android.support.v4.view.PagerTabStrip两个组件，可以在布局文件中，作为ViewPager的子标签，并设定相对与ViewPager的位置(比如顶部)。但这两个组件都很丑，并且会随着页面一起滑动，所以一般都不用。

其实实现一个滑块标志当前页面也很简单，大概需要两步：

第一步 在布局文件ViewPager的上方放置一个ImageView组件，组件可以是图片或是shape资源。注意需要把ImageView的scaleType属性设为matrix，就是说该组件的位置和大小由一个变换矩阵来控制；

第二步 在Activity中为ViewPager组件添加OnPageChangeListener监听器。在OnPageChangeListener里设定matrix，用于控制指示滑块ImageView的位置。该监听器需要实现三个方法：

onPageScrollStateChanged：用于监听滑动状态的改变

onPageScrolled：用于监听滑动的动作

onPageSeleted:用于监听页面的切换，即某个页面被选中了作为当前页面。

一般实现onPageSelected方法就可以，其他两个方法可以空着。另外为了使页面切换时滑块也是平滑地滑动，可以给滑块的ImageView指定一个TranslateAnimation动画，指定动画用setAnimation，TranlateAnimation也很简单，有个构造函数是TranslateAnimation(int beginX,int endX,int beginY,int endY)，将运动矢量的起始位置和终止位置传给它就好了。

下面我们来看五个具体的例子：

一 实现ViewPager（数据源为List<View>）

1.先在main.xml文件中添加一个ViewPager:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" > 
  <android.support.v4.view.ViewPager 
    android:id="@+id/pager" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"> 
  </android.support.v4.view.ViewPager> 
</LinearLayout> 

2.创建三个View:

<?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" > 
  <TextView 
    android:id="@+id/txt1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center" 
    android:textSize="25dp" 
    android:text="第一页" > 
  </TextView> 
</LinearLayout> 

<?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" > 
  <TextView 
    android:id="@+id/txt2" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="第二页" > 
  </TextView> 
</LinearLayout> 

<?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" >
  <TextView
    android:id="@+id/txt3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="第三页" >
  </TextView>
</LinearLayout>

3.创建一个ViewPager适配器类：

package com.yayun.viewpagerdemo; 
import java.util.ArrayList; 
import java.util.List; 
import android.support.v4.view.PagerAdapter; 
import android.view.View; 
import android.view.ViewGroup; 
public class ViewPagerAdapter extends PagerAdapter { 
  private List<View> lViews=new ArrayList<View>(); 
  public ViewPagerAdapter(List<View> lViews){ 
    this.lViews=lViews; 
  } 
  @Override 
  public int getCount() { 
    return lViews.size(); 
  } 
  @Override 
  public boolean isViewFromObject(View arg0, Object arg1) { 
    return arg0==arg1; 
  } 
  @Override 
  public Object instantiateItem(ViewGroup container, int position) { 
    container.addView(lViews.get(position)); 
    return lViews.get(position); 
  } 
  @Override 
  public void destroyItem(ViewGroup container, int position, Object object) { 
    container.removeView(lViews.get(position)); 
  } 
} 

4.MainActivity.java:

package com.yayun.viewpagerdemo; 
import java.util.ArrayList; 
import java.util.List; 
import android.support.v7.app.ActionBarActivity; 
import android.support.v7.app.ActionBar; 
import android.support.v4.app.Fragment; 
import android.support.v4.view.PagerAdapter; 
import android.support.v4.view.ViewPager; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.Window; 
import android.os.Build; 
public class MainActivity extends ActionBarActivity { 
  private ViewPager viewPager; 
  private List<View> listViews=null; 
  ViewPagerAdapter pagerAdapter; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.activity_main); 
    viewPager=(ViewPager) findViewById(R.id.pager); 
    listViews=new ArrayList<View>(); 
     
    View view1=View.inflate(this, R.layout.view1, null); 
    View view2=View.inflate(this, R.layout.view2, null); 
    View view3=View.inflate(this, R.layout.view3, null); 
    listViews.add(view1); 
    listViews.add(view2); 
    listViews.add(view3); 
    pagerAdapter=new ViewPagerAdapter(listViews) ; 
    viewPager.setAdapter(pagerAdapter); 
  } 
} 

5.运行实例：

可以实现翻页效果。

二 添加
1.我们需要更改main.xml文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" > 
  <android.support.v4.view.ViewPager 
    android:id="@+id/pager" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center" > 
    <android.support.v4.view.PagerTabStrip 
      android:id="@+id/strip" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_gravity="top" > 
    </android.support.v4.view.PagerTabStrip> 
  </android.support.v4.view.ViewPager> 
</LinearLayout> 

2.需要更改适配器文件：

package com.yayun.viewpagerdemo; 
import java.util.ArrayList; 
import java.util.List; 
import android.support.v4.view.PagerAdapter; 
import android.view.View; 
import android.view.ViewGroup; 
public class ViewPagerAdapter extends PagerAdapter { 
  private List<View> lViews=new ArrayList<View>(); 
  private List<String> titleList=new ArrayList<String>(); 
  public ViewPagerAdapter(List<View> lViews,List<String> titleList){ 
    this.lViews=lViews; 
    this.titleList=titleList; 
  } 
  @Override 
  public int getCount() { 
    return lViews.size(); 
  } 
  @Override 
  public boolean isViewFromObject(View arg0, Object arg1) { 
    return arg0==arg1; 
  } 
  @Override 
  public Object instantiateItem(ViewGroup container, int position) { 
    container.addView(lViews.get(position)); 
    return lViews.get(position); 
  } 
  @Override 
  public void destroyItem(ViewGroup container, int position, Object object) { 
    container.removeView(lViews.get(position)); 
  } 
   
  @Override 
  public CharSequence getPageTitle(int position) { 
    // TODO Auto-generated method stub 
    return titleList.get(position); 
  } 
} 

3.需要更改MainActivity.java文件：

package com.yayun.viewpagerdemo; 
import java.util.ArrayList; 
import java.util.List; 
import android.support.v7.app.ActionBarActivity; 
import android.support.v7.app.ActionBar; 
import android.support.v4.app.Fragment; 
import android.support.v4.view.PagerAdapter; 
import android.support.v4.view.PagerTabStrip; 
import android.support.v4.view.ViewPager; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.Window; 
import android.os.Build; 
public class MainActivity extends ActionBarActivity { 
  private ViewPager viewPager; 
  private List<View> listViews=null; 
  ViewPagerAdapter pagerAdapter; 
  PagerTabStrip pagerTabStrip; 
  private List<String> titleList; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.activity_main); 
    viewPager=(ViewPager) findViewById(R.id.pager); 
    pagerTabStrip=(PagerTabStrip) findViewById(R.id.strip); 
    listViews=new ArrayList<View>(); 
    titleList=new ArrayList<String>(); 
    titleList.add("第一页"); 
    titleList.add("第二页"); 
    titleList.add("第三页"); 
     
    View view1=View.inflate(this, R.layout.view1, null); 
    View view2=View.inflate(this, R.layout.view2, null); 
    View view3=View.inflate(this, R.layout.view3, null); 
    listViews.add(view1); 
    listViews.add(view2); 
    listViews.add(view3); 
    pagerAdapter=new ViewPagerAdapter(listViews,titleList) ; 
    viewPager.setAdapter(pagerAdapter); 
  } 
} 

4.运行实例如下：

三 实现ViewPager(数据源为List<Fragment>)
1.首先我们要创建三个Fragment:

package com.yayun.viewpagerdemo; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
public class Fragment1 extends Fragment { 
  @Override 
  public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
    return inflater.inflate(R.layout.view1, container, false); 
  } 
} 
package com.yayun.viewpagerdemo; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
public class Fragment2 extends Fragment { 
  @Override 
  public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
    return inflater.inflate(R.layout.view2, container, false); 
  } 
} 
package com.yayun.viewpagerdemo; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
public class Fragment3 extends Fragment { 
  @Override 
  public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
    return inflater.inflate(R.layout.view3, container, false); 
  } 
} 

2.设置Adapter:

package com.yayun.viewpagerdemo; 
import java.util.List; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 
public class MyFragmentPagerAdapter extends FragmentPagerAdapter { 
  List<Fragment> fragmentsList; 
  List<String> titleList; 
  public MyFragmentPagerAdapter(FragmentManager fm,List<Fragment> fragmentsList,List<String> titleList) { 
    super(fm); 
    this.fragmentsList=fragmentsList; 
    this.titleList=titleList; 
  } 
  @Override 
  public Fragment getItem(int arg0) { 
    // TODO Auto-generated method stub 
    return fragmentsList.get(arg0); 
  } 
  @Override 
  public int getCount() { 
    // TODO Auto-generated method stub 
    return fragmentsList.size(); 
  } 
@Override 
 
public CharSequence getPageTitle(int position) { 
  // TODO Auto-generated method stub 
  return titleList.get(position); 
} 
} 

3.MainActivity.java:

package com.yayun.viewpagerdemo; 
import java.util.ArrayList; 
import java.util.List; 
import android.graphics.Color; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v4.view.PagerTabStrip; 
import android.support.v4.view.ViewPager; 
import android.support.v4.view.ViewPager.PageTransformer; 
import android.support.v7.app.ActionBarActivity; 
import android.view.View; 
import android.view.Window; 
public class MainActivity extends ActionBarActivity { 
  private ViewPager viewPager; 
  private List<View> listViews=null; 
  ViewPagerAdapter pagerAdapter; 
  PagerTabStrip pagerTabStrip; 
  private List<String> titleList; 
  private List<Fragment> fragmentsList; 
  MyFragmentPagerAdapter myFragmentPagerAdapter; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.activity_main); 
    viewPager=(ViewPager) findViewById(R.id.pager); 
    pagerTabStrip=(PagerTabStrip) findViewById(R.id.strip); 
     
    pagerTabStrip.setBackgroundColor(Color.GREEN); 
    pagerTabStrip.setDrawFullUnderline(false); 
    pagerTabStrip.setTextColor(Color.WHITE); 
    listViews=new ArrayList<View>(); 
    titleList=new ArrayList<String>(); 
    fragmentsList=new ArrayList<Fragment>(); 
    fragmentsList.add(new Fragment1()); 
    fragmentsList.add(new Fragment2()); 
    fragmentsList.add(new Fragment3()); 
    titleList.add("第一页"); 
    titleList.add("第二页"); 
    titleList.add("第三页"); 
     
    View view1=View.inflate(this, R.layout.view1, null); 
    View view2=View.inflate(this, R.layout.view2, null); 
    View view3=View.inflate(this, R.layout.view3, null); 
    listViews.add(view1); 
    listViews.add(view2); 
    listViews.add(view3); 
    pagerAdapter=new ViewPagerAdapter(listViews,titleList) ; 
    myFragmentPagerAdapter=new MyFragmentPagerAdapter(getSupportFragmentManager(), fragmentsList, titleList); 
    //viewPager.setAdapter(pagerAdapter); 
    viewPager.setAdapter(myFragmentPagerAdapter); 
  } 
} 

4.运行实例：

这种方法不会销毁不在当前页面的页面，不能实现页卡的创建和销毁。

四 实现ViewPager(数据源为List<Fragment>实现FargmentStatePagerAdapter)常用
改变Adapter:

package com.yayun.viewpagerdemo; 
import java.util.List; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 
import android.support.v4.app.FragmentStatePagerAdapter; 
import android.view.View; 
public class MyFragmentPagerAdapter2 extends FragmentStatePagerAdapter { 
  List<Fragment> fragmentsList; 
  List<String> titleList; 
  public MyFragmentPagerAdapter2(FragmentManager fm,List<Fragment> fragmentsList,List<String> titleList) { 
    super(fm); 
    this.fragmentsList=fragmentsList; 
    this.titleList=titleList; 
  } 
  @Override 
  public Fragment getItem(int arg0) { 
    // TODO Auto-generated method stub 
    return fragmentsList.get(arg0); 
  } 
  @Override 
  public int getCount() { 
    // TODO Auto-generated method stub 
    return fragmentsList.size(); 
  } 
@Override 
 
public CharSequence getPageTitle(int position) { 
  // TODO Auto-generated method stub 
  return titleList.get(position); 
} 
@Override 
public Object instantiateItem(View container, int position) { 
  // TODO Auto-generated method stub 
  return super.instantiateItem(container, position); 
} 
@Override 
public void destroyItem(View container, int position, Object object) { 
  // TODO Auto-generated method stub 
  super.destroyItem(container, position, object); 
} 
} 

将MainActivity.java中的Adapter换一下即可，它可以实现页卡的创建和销毁。

五  onPagerChangeListener 监听使用
只需要修改MainActivity.java:

package com.yayun.viewpagerdemo; 
import java.util.ArrayList; 
import java.util.List; 
import android.graphics.Color; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v4.view.PagerTabStrip; 
import android.support.v4.view.ViewPager; 
import android.support.v4.view.ViewPager.OnPageChangeListener; 
import android.support.v4.view.ViewPager.PageTransformer; 
import android.support.v7.app.ActionBarActivity; 
import android.view.View; 
import android.view.Window; 
import android.widget.Toast; 
public class MainActivity extends ActionBarActivity implements OnPageChangeListener { 
  private ViewPager viewPager; 
  private List<View> listViews=null; 
  ViewPagerAdapter pagerAdapter; 
  PagerTabStrip pagerTabStrip; 
  private List<String> titleList; 
  private List<Fragment> fragmentsList; 
  MyFragmentPagerAdapter myFragmentPagerAdapter; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.activity_main); 
    viewPager=(ViewPager) findViewById(R.id.pager); 
    pagerTabStrip=(PagerTabStrip) findViewById(R.id.strip); 
     
    pagerTabStrip.setBackgroundColor(Color.GREEN); 
    pagerTabStrip.setDrawFullUnderline(false); 
    pagerTabStrip.setTextColor(Color.WHITE); 
    listViews=new ArrayList<View>(); 
    titleList=new ArrayList<String>(); 
    fragmentsList=new ArrayList<Fragment>(); 
    fragmentsList.add(new Fragment1()); 
    fragmentsList.add(new Fragment2()); 
    fragmentsList.add(new Fragment3()); 
    titleList.add("第一页"); 
    titleList.add("第二页"); 
    titleList.add("第三页"); 
     
    View view1=View.inflate(this, R.layout.view1, null); 
    View view2=View.inflate(this, R.layout.view2, null); 
    View view3=View.inflate(this, R.layout.view3, null); 
    listViews.add(view1); 
    listViews.add(view2); 
    listViews.add(view3); 
    pagerAdapter=new ViewPagerAdapter(listViews,titleList) ; 
    myFragmentPagerAdapter=new MyFragmentPagerAdapter(getSupportFragmentManager(), fragmentsList, titleList); 
    //viewPager.setAdapter(pagerAdapter); 
    viewPager.setAdapter(myFragmentPagerAdapter); 
    viewPager.setOnPageChangeListener(this);//加载监听器 
  } 
  @Override 
  public void onPageScrollStateChanged(int arg0) { 
    // TODO Auto-generated method stub 
  } 
  @Override 
  public void onPageScrolled(int arg0, float arg1, int arg2) { 
    // TODO Auto-generated method stub 
  } 
  @Override 
  public void onPageSelected(int arg0) { 
    Toast.makeText(this, "当前页面为"+(arg0+1), Toast.LENGTH_SHORT).show(); 
  } 
} 

运行实例即可以显示当前页面标签。

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