Github-Client（ANDROID）开源之旅（三) ------ 巧用ViewPagerIndicator .

github ViewPagerIndicator tab

接上篇博文：Github-Client（ANDROID）开源之旅（二) ------ 浅析ActionBarSherkLock

文中结合了网易新闻客户端讲解了开源库ActionBarSherklock的使用

今天夏老师再给大家讲解一个开源库的使用，它就是ViewPagerIndicator（同样出自JakeWharton之手，ps：这胖子还是蛮厉害的）

官网地址：http://viewpagerindicator.com/

Github地址：https://github.com/JakeWharton/Android-ViewPagerIndicator

ViewPagerIndicator作为一款分页指标小部件兼容ViewPager，封装上做得还是不错的，目前为众多知名应用所使用

具体API使用大家下载官方demo示例瞅瞅就欧了（链接库都不懂得怎么引用的童鞋自个儿先去补补课）

以下是官网的效果图

本文就以优化大师的TAB滑动标签页为例来讲解该库的扩展使用

先上效果图,原版

山寨版

玩过优化大师的童鞋应该注意到，tab底部的下划线是会随着pager的滑动而实时变化，而网上很多demo则是标签页切换时下划线的动画效果，二者是有区别的，当然只要在onPageScrolled添加一些处理同样可以达到效果，不过代码就多了很多额外处理，另外这么做也不够通用，本着不重复发明轮子的原则，我们只需对现有控件做一些改造就可以实现我们想要的效果了

先看layout文件：

[java] view plain copy print ?

1. <LinearLayout  
2.         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.         android:background="#dddddd">  
7.           
8.       
9.         <RelativeLayout  
10.         android:layout_width="fill_parent"  
11.         android:layout_height="40dp"  
12.         android:background="#074060">  
13.           
14.                 <TextView  
15.                 android:id="@+id/title"  
16.                 android:layout_width="wrap_content"  
17.                 android:layout_height="wrap_content"  
18.                 android:layout_centerInParent="true"  
19.                 android:text="安卓优化大师"  
20.                 android:textColor="#eeeeee"  
21.                 android:textSize="20sp"/>                  
22.               
23.                 <ImageView  
24.                  android:layout_width="wrap_content"  
25.                  android:layout_height="wrap_content"  
26.                  android:src="@drawable/titlebar_logo"  
27.                  android:layout_centerVertical="true"  
28.                  android:layout_toLeftOf="@id/title"  
29.                  android:layout_marginRight="10dp"/>  
30.           
31.         </RelativeLayout>  
32.           
33.         <LinearLayout  
34.         android:layout_width="fill_parent"  
35.         android:layout_height="35dp"  
36.         android:orientation="vertical"  
37.         android:background="@drawable/main_header_background">  
38.           
39.                 <com.viewpagerindicator.TabPageIndicator  
40.                 android:id="@+id/tab_indicator"  
41.                 android:layout_height="wrap_content"  
42.                 android:layout_width="fill_parent"/>  
43.               
44.                 <com.lance.tablinepagerindictor.widget.UnderlinePageIndicatorEx  
45.                 android:id="@+id/underline_indicator"  
46.                 android:layout_height="3dp"  
47.                 android:layout_width="fill_parent"  
48.                 android:layout_alignParentBottom="true"/>  
49.           
50.        </LinearLayout>       
51.          
52.        <android.support.v4.view.ViewPager  
53.         android:id="@+id/pager"  
54.         android:layout_width="fill_parent"  
55.         android:layout_height="fill_parent"/>  
56.           
57.       
58. </LinearLayout>  

<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical"
        android:background="#dddddd">
        
    
    	<RelativeLayout
    	android:layout_width="fill_parent"
        android:layout_height="40dp"
        android:background="#074060">
        
	        	<TextView
	        	android:id="@+id/title"
	            android:layout_width="wrap_content"
        		android:layout_height="wrap_content"
        		android:layout_centerInParent="true"
        		android:text="安卓优化大师"
        		android:textColor="#eeeeee"
        		android:textSize="20sp"/>	            
	        
	        	<ImageView
        	     android:layout_width="wrap_content"
       			 android:layout_height="wrap_content"
       			 android:src="@drawable/titlebar_logo"
       			 android:layout_centerVertical="true"
       			 android:layout_toLeftOf="@id/title"
       			 android:layout_marginRight="10dp"/>
 	    
    	</RelativeLayout>
        
        <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="35dp"
        android:orientation="vertical"
        android:background="@drawable/main_header_background">
        
		        <com.viewpagerindicator.TabPageIndicator
		        android:id="@+id/tab_indicator"
		        android:layout_height="wrap_content"
		        android:layout_width="fill_parent"/>
		    
		        <com.lance.tablinepagerindictor.widget.UnderlinePageIndicatorEx
		        android:id="@+id/underline_indicator"
		        android:layout_height="3dp"
		        android:layout_width="fill_parent"
		        android:layout_alignParentBottom="true"/>
        
       </LinearLayout>     
       
       <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>
        
    
</LinearLayout>

再看UnderlinePageIndicatorEx的实现

[java] view plain copy print ?

1. public class UnderlinePageIndicatorEx extends UnderlinePageIndicator{  
2.   
3.        public UnderlinePageIndicatorEx(Context context) {  
4.            super(context, null);  
5.              
6.         }  
7.   
8.         public UnderlinePageIndicatorEx(Context context, AttributeSet attrs) {  
9.             super(context, attrs, R.attr.vpiUnderlinePageIndicatorStyle);  
10.               
11.         }  
12.   
13.         public UnderlinePageIndicatorEx(Context context, AttributeSet attrs, int defStyle) {  
14.             super(context, attrs, defStyle);  
15.               
16.         }  
17.           
18.           
19.         @Override  
20.         public void setViewPager(ViewPager viewPager) {  
21.             if (mViewPager == viewPager) {  
22.                 return;  
23.             }  
24. //          if (mViewPager != null) {   
25. //              //Clear us from the old pager.   
26. //              mViewPager.setOnPageChangeListener(null);   
27. //          }   
28.             if (viewPager.getAdapter() == null) {  
29.                 throw new IllegalStateException("ViewPager does not have adapter instance.");  
30.             }  
31.             mViewPager = viewPager;  
32. //          mViewPager.setOnPageChangeListener(this);   
33.             invalidate();  
34.             post(new Runnable() {  
35.                 @Override public void run() {  
36.                     if (mFades) {  
37.                         post(mFadeRunnable);  
38.                     }  
39.                 }  
40.             });  
41.         }  
42. }  

public class UnderlinePageIndicatorEx extends UnderlinePageIndicator{

	   public UnderlinePageIndicatorEx(Context context) {
		   super(context, null);
		   
	    }

	    public UnderlinePageIndicatorEx(Context context, AttributeSet attrs) {
	    	super(context, attrs, R.attr.vpiUnderlinePageIndicatorStyle);
	    	
	    }

	    public UnderlinePageIndicatorEx(Context context, AttributeSet attrs, int defStyle) {
	        super(context, attrs, defStyle);
	        
	    }
	    
	    
	    @Override
	    public void setViewPager(ViewPager viewPager) {
	        if (mViewPager == viewPager) {
	            return;
	        }
//	        if (mViewPager != null) {
//	            //Clear us from the old pager.
//	            mViewPager.setOnPageChangeListener(null);
//	        }
	        if (viewPager.getAdapter() == null) {
	            throw new IllegalStateException("ViewPager does not have adapter instance.");
	        }
	        mViewPager = viewPager;
//	        mViewPager.setOnPageChangeListener(this);
	        invalidate();
	        post(new Runnable() {
	            @Override public void run() {
	                if (mFades) {
	                    post(mFadeRunnable);
	                }
	            }
	        });
	    }
}

UnderlinePageIndicatorEx继承了UnderlinePageIndicator，前面提到链接库有所改动

事实上就是把成员变量的访问权限由private改为protected,然后重写了setViewPager方法(why?自个儿琢磨去)

最后看看activity中如何调用

[java] view plain copy print ?

1. public class MainActivity extends FragmentActivity {  
2.   
3.     private ContentFrameAdapter mContentAdapter;  
4.     private ViewPager mPager;  
5.     private TabPageIndicator mTabPageIndicator;  
6.     private UnderlinePageIndicatorEx mUnderlinePageIndicator;  
7.       
8.       
9.     private  int COUNT = 0;  
10.     private List<TitleStruct> mTitleList;  
11.     private List<ContentStruct> mContentList;  
12.       
13.       
14.       
15.   
16.     @Override  
17.     protected void onCreate(Bundle arg0) {  
18.   
19.         super.onCreate(arg0);  
20.         requestWindowFeature(Window.FEATURE_NO_TITLE);   
21.         getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,     
22.                     WindowManager.LayoutParams.FLAG_FULLSCREEN);    
23.         setContentView(R.layout.activity_main);  
24.           
25.         initData();  
26.         setupViews();  
27.   
28.     }  
29.   
30.   
31.     private void setupViews(){        
32.            
33.          mPager = (ViewPager)findViewById(R.id.pager);  
34.          mPager.setAdapter(mContentAdapter);   
35.           
36.          mTabPageIndicator = (TabPageIndicator) findViewById(R.id.tab_indicator);     
37.          mTabPageIndicator.setViewPager(mPager);       
38.            
39.          mUnderlinePageIndicator = (UnderlinePageIndicatorEx)findViewById(R.id.underline_indicator);  
40.          mUnderlinePageIndicator.setViewPager(mPager);  
41.          mUnderlinePageIndicator.setFades(false);  
42.            
43.          mTabPageIndicator.setOnPageChangeListener(mUnderlinePageIndicator);  
44.     }  
45.       
46.       
47.     private void initData(){  
48.          mContentList = new ArrayList<ContentStruct>();  
49.          mTitleList = new ArrayList<TitleStruct>();  
50.           
51.          String[] arrStrings = getResources().getStringArray(R.array.sections);  
52.          COUNT = arrStrings.length;  
53.          for (int i = 0; i < COUNT; i++) {  
54.              ContentStruct object = new ContentStruct();  
55.              object.daString = arrStrings[i];  
56.              object.index = i;        
57.              mContentList.add(object);  
58.                
59.              TitleStruct object2 = new TitleStruct(arrStrings[i]);  
60.              mTitleList.add(object2);  
61.          }  
62.            
63.            
64.          mContentAdapter = new ContentFrameAdapter(getSupportFragmentManager());  
65.          mContentAdapter.setContentList(mContentList);  
66.          mContentAdapter.setTitleList(mTitleList);  
67.      
68.     }  
69.   
70. }  

public class MainActivity extends FragmentActivity {

	private ContentFrameAdapter mContentAdapter;
	private ViewPager mPager;
	private TabPageIndicator mTabPageIndicator;
	private UnderlinePageIndicatorEx mUnderlinePageIndicator;
	
	
	private  int COUNT = 0;
	private List<TitleStruct> mTitleList;
	private List<ContentStruct> mContentList;
	
	
	

	@Override
	protected void onCreate(Bundle arg0) {

		super.onCreate(arg0);
		requestWindowFeature(Window.FEATURE_NO_TITLE); 
		getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,   
	                WindowManager.LayoutParams.FLAG_FULLSCREEN);  
		setContentView(R.layout.activity_main);
		
		initData();
		setupViews();

	}


	private void setupViews(){		
	     
	     mPager = (ViewPager)findViewById(R.id.pager);
		 mPager.setAdapter(mContentAdapter); 
		
	     mTabPageIndicator = (TabPageIndicator) findViewById(R.id.tab_indicator);   
	     mTabPageIndicator.setViewPager(mPager);     
	     
	     mUnderlinePageIndicator = (UnderlinePageIndicatorEx)findViewById(R.id.underline_indicator);
	     mUnderlinePageIndicator.setViewPager(mPager);
	     mUnderlinePageIndicator.setFades(false);
	     
	     mTabPageIndicator.setOnPageChangeListener(mUnderlinePageIndicator);
	}
	
	
	private void initData(){
		 mContentList = new ArrayList<ContentStruct>();
		 mTitleList = new ArrayList<TitleStruct>();
		
		 String[] arrStrings = getResources().getStringArray(R.array.sections);
	     COUNT = arrStrings.length;
         for (int i = 0; i < COUNT; i++) {
        	 ContentStruct object = new ContentStruct();
        	 object.daString = arrStrings[i];
        	 object.index = i;      
        	 mContentList.add(object);
        	 
        	 TitleStruct object2 = new TitleStruct(arrStrings[i]);
        	 mTitleList.add(object2);
         }
         
    	 
		 mContentAdapter = new ContentFrameAdapter(getSupportFragmentManager());
	     mContentAdapter.setContentList(mContentList);
	     mContentAdapter.setTitleList(mTitleList);
   
	}

}

简洁明了，是不是比在activity添加一堆乱七八糟的东西要好看的多？

其它的就没啥好咋乎的了，最后附上工程链接：

http://download.youkuaiyun.com/detail/geniuseoe2012/5641165