Android TabWidget

首先先看一个小例子，接着讲解原理

 TabTest.java

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 package org.hualang.tab;
 import android.app.Activity;
 import android.app.TabActivity;
 import android.graphics.Color;
 import android.os.Bundle;
 import android.widget.TabHost;
 import android.widget.Toast;
 import android.widget.TabHost.OnTabChangeListener;
 public class TabTest extends TabActivity {
     /** Called when the activity is first created. */
     TabHost tabhost;
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         //取得TabHost对象
         tabhost = getTabHost();
         //为TabHost添加标签
         //新建一个newTabSpec(newTabSpec)
         //设置其标签和图标（setIndicator）
         //设置内容（setContent）
         tabhost.addTab(tabhost.newTabSpec("tab1")
                 .setIndicator("TAB 1",getResources().getDrawable(R.drawable.img1))
                 .setContent(R.id.text1));
         tabhost.addTab(tabhost.newTabSpec("tab2")
                 .setIndicator("TAB 2",getResources().getDrawable(R.drawable.img2))
                 .setContent(R.id.text2));
         tabhost.addTab(tabhost.newTabSpec("tab3")
                 .setIndicator("TAB 3",getResources().getDrawable(R.drawable.img3))
                 .setContent(R.id.text3));
         //设置TabHost的背景颜色
         //tabhost.setBackgroundColor(Color.argb(150,22,70,150));
         //设置TabHost的背景图片资源
         tabhost.setBackgroundResource(R.drawable.bg0);
         //设置当前显示哪个标签
         tabhost.setCurrentTab(0);
         //标签切换事件处理，setOnTabChangedListener
         tabhost.setOnTabChangedListener(new OnTabChangeListener()
         {
             public void onTabChanged(String tabId)
             {
                 Toast toast=Toast.makeText(getApplicationContext(), "现在是"+tabId+"标签", Toast.LENGTH_SHORT);
                 toast.show();
             }
         });

     }
 }

 

main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <TabHost xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@android:id/tabhost"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent">
     <LinearLayout
         android:orientation="vertical"
         android:layout_width="fill_parent"
         android:layout_height="fill_parent">
         <TabWidget
             android:id="@android:id/tabs"
             android:layout_width="fill_parent"
             android:layout_height="wrap_content" />
         <FrameLayout
             android:id="@android:id/tabcontent"
             android:layout_width="fill_parent"
             android:layout_height="fill_parent">
             <TextView
                 android:id="@+id/text1"
                 android:layout_width="fill_parent"
                 android:layout_height="fill_parent"
                 android:text="选项卡1" />
             <TextView
                 android:id="@+id/text2"
                 android:layout_width="fill_parent"
                 android:layout_height="fill_parent"
                 android:text="选项卡2" />
             <TextView
                 android:id="@+id/text3"
                 android:layout_width="fill_parent"
                 android:layout_height="fill_parent"
                 android:text="选项卡3" />
         </FrameLayout>
     </LinearLayout>
 </TabHost>

Android TabWidget的实现可以分为二种，一种是使用标准TabActivity实现，另外一种可以自定义方式实现，这种方法实现起来相对比较复杂，但对于要实现比较多元化的view是很好的，这里我们简单看下源码

一、通用做法

继承TabActivity，实现自己的TabActivity

 import android.app.Activity;
 import android.app.TabActivity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.widget.TabHost;
 import android.widget.TabHost.OnTabChangeListener;
 public class TabWidgetDemo2 extends TabActivity implements OnTabChangeListener {
      private TabHost mTabHost;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);

         setContentView(R.layout.tabwidgetdemo2);
         mTabHost = getTabHost();
         mTabHost.setOnTabChangedListener(this);
         setupTab1();
         setupTab2();
         mTabHost.setCurrentTab(1);
     }
     private void setupTab2() {
         // TODO Auto-generated method stub
         Intent intent = new Intent();
         intent.setAction(Intent.ACTION_MAIN);
         intent.setClass(this, TabWidget2.class);
         mTabHost.addTab(mTabHost.newTabSpec("TabWidget2")
                 .setIndicator("TabWidget2",getResources().getDrawable(R.drawable.icon))
                 .setContent(intent));
     }
     private void setupTab1() {
         // TODO Auto-generated method stub
         Intent intent = new Intent();
         intent.setAction(Intent.ACTION_MAIN);
         intent.setClass(this, TabWidget1.class);
         mTabHost.addTab(mTabHost.newTabSpec("TabWidget1")
                 .setIndicator("TabWidget1",getResources().getDrawable(R.drawable.icon))
                 .setContent(intent));
     }
     public void onTabChanged(String tabId) {
         // TODO Auto-generated method stub
         Activity activity = getLocalActivityManager().getActivity(tabId);
         if (activity != null) {
             activity.onWindowFocusChanged(true);
         }
     }


 }

二个tab对应的Activity，先看TabWidget1，这个类在第二种实现中还会用到，因此我们可以看到对Action的判断。

 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import com.android.exampledemo.R;
 import com.android.exampledemo.util.DemoUtils;
 public class TabWidget1 extends Activity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);

         Intent intent = this.getIntent();
         if (intent.getAction().equals(Intent.ACTION_MAIN)){
             setContentView(R.layout.tabwidgetdemo2_1);
         }
         else {
             setContentView(R.layout.tabwidget_1);
             DemoUtils.updateButtonBar((Activity)this,R.id.contactstab);
         }
     }
 }

 

再看一下TabWidget2，这个Activity我们在第二种实现方式中也会用到。

 import com.android.exampledemo.R;
 import com.android.exampledemo.util.DemoUtils;
 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 public class TabWidget2 extends Activity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);

         Intent intent = this.getIntent();

         if (intent.getAction().equals(Intent.ACTION_MAIN)){
             setContentView(R.layout.tabwidgetdemo2_1);
         }
         else {
             setContentView(R.layout.tabwidget_2);
             DemoUtils.updateButtonBar((Activity)this,R.id.groupstab);
         }
     }
 }

 

最后就是各个Activity对应的layout

1.tabwidgetdemo2.xml

 <?xml version="1.0" encoding="utf-8"?>
 <TabHost
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@android:id/tabhost"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent">
   <LinearLayout
     android:orientation="vertical"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent">
     <TabWidget android:id="@android:id/tabs"
         android:layout_width="fill_parent"
         android:layout_height="68dip"
         android:paddingLeft="1dip"
         android:paddingRight="1dip"
         android:paddingTop="4dip"
         />
     <FrameLayout android:id="@android:id/tabcontent"
         android:layout_width="fill_parent"
         android:layout_height="0dip"
         android:layout_weight="1"
         />
     </LinearLayout>
 </TabHost>

2.二个sub tab对应的layout

 Layout1
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:background="#FFF">
   <TextView android:id="@+id/textview"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text="Tab Widget first">
    </TextView>
 </LinearLayout>
 Layout2
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:background="#FFF">
   <TextView android:id="@+id/textview"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text="Tab Widget second">
    </TextView>
 </LinearLayout>

 

 

方法2：

先创建一个Activity （TabWidgetDemo）

 1.TabWidgetDemo.java
 import com.android.exampledemo.R;
 import com.android.exampledemo.util.DemoUtils;
 import android.app.Activity;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.os.Bundle;
 //not use tabhost to organized
 public class TabWidgetDemo extends Activity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);
         //int activeTab = DemoUtils.getIntPref(this, "activetab", R.id.artisttab);
         SharedPreferences prefs =
             getSharedPreferences(getPackageName(), Context.MODE_PRIVATE);
         int activeTab = prefs.getInt("activetab", R.id.contactstab);
         if (activeTab != R.id.contactstab
                 && activeTab != R.id.groupstab) {
             activeTab = R.id.contactstab;
         }
         DemoUtils.activateTab(this, activeTab);
     }
 }
 2.DemoUtils
 import android.app.Activity;
 import android.content.Intent;
 import android.net.Uri;
 import android.view.View;
 import android.widget.TabWidget;
 import com.android.exampledemo.R;
 public class DemoUtils {
     static int sActiveTabIndex = -1;

     public static void activateTab(Activity a,int active_id){
         Intent intent = new Intent(Intent.ACTION_PICK);
         switch (active_id) {
         case R.id.contactstab:
             intent.setDataAndType(Uri.EMPTY, "vnd.android.cursor.dir/tb_contacts");
             break;
         case R.id.groupstab:
             intent.setDataAndType(Uri.EMPTY, "vnd.android.cursor.dir/tb_groups");
             break;
         default:
             return;
         }
         intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
         a.startActivity(intent);
         a.finish();
         a.overridePendingTransition(0,0);
     }


     public static void updateButtonBar(Activity a, int highlight) {
         final TabWidget ll = (TabWidget) a.findViewById(R.id.buttonbar);

          for (int i = ll.getChildCount() - 1; i >= 0; i--) {
              View v = ll.getChildAt(i);
              boolean isActive = (v.getId() == highlight);
              if (isActive) {
                     ll.setCurrentTab(i);
                     sActiveTabIndex = i;
              }

              v.setTag(i);
              v.setOnClickListener(new View.OnClickListener() {
                     public void onClick(View v) {
                         int id = v.getId();
                         if (id == ll.getChildAt(sActiveTabIndex).getId()) {
                             return;
                         }
                         activateTab((Activity)ll.getContext(),id );
                         ll.setCurrentTab((Integer) v.getTag());
                     }});
          }
     }
 }

 

 

二个Tab sub activity前一方法中已经给出，这里我们只需要看一下layout的实现就可以了

1>buttonbar.xml

 <?xml version="1.0" encoding="utf-8"?>
 <TabWidget xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/buttonbar"
     android:layout_width="match_parent"
     android:layout_height="wrap_content" >
     <TextView
         android:id="@+id/contactstab"
         android:focusable="true"
         android:drawableTop="@drawable/icon"
         android:background="@drawable/buttonbarbackground"
         android:text="Contacts"
         android:textColor="@color/tab_indicator_text"
         android:textAppearance="?android:attr/textAppearanceSmall"
         android:paddingTop="7dip"
         android:paddingBottom="2dip"
         android:gravity="center"
         android:layout_weight="1"
         android:layout_marginLeft="-3dip"
         android:layout_marginRight="-3dip"
         android:layout_width="match_parent"
         android:layout_height="84dip"
         android:singleLine="true"
         android:ellipsize="marquee" />
     <TextView
         android:id="@+id/groupstab"
         android:focusable="true"
         android:drawableTop="@drawable/icon"
         android:background="@drawable/buttonbarbackground"
         android:text="Group"
         android:textColor="@color/tab_indicator_text"
         android:textAppearance="?android:attr/textAppearanceSmall"
         android:paddingTop="7dip"
         android:paddingBottom="2dip"
         android:gravity="center"
         android:layout_weight="1"
         android:layout_marginLeft="-3dip"
         android:layout_marginRight="-3dip"
         android:layout_width="match_parent"
         android:layout_height="84dip"
         android:singleLine="true"
         android:ellipsize="marquee" />
 </TabWidget>

2>tabwidget_1.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent">

   <include layout="@layout/battonbar" />

   <ExpandableListView android:id="@+id/android:list"
                   android:layout_width="fill_parent"
                   android:layout_height="wrap_content"
                   android:footerDividersEnabled="true"
                   android:fadeScrollbars="true"
                   android:drawSelectorOnTop="true">
   </ExpandableListView>

 </LinearLayout>

3> tabwidget_2.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent">

   <include layout="@layout/battonbar" />

 </LinearLayout>