动态设置 TabHost选项卡属性及自定义TabHost选项Layout

TabHost生成后会向内添加TabSpec以形成选项栏：

如果是继承的TabActivity类：

 tabhost = getTabHost();
 tabhost.addTab(tabhost.newTabSpec("1" ).setIndicator( "TAB 1" , getResources().getDrawable(R.drawable.icon)).setContent(R.id.text1));
 tabhost.setCurrentTab(0 );

tabhost = getTabHost(); tabhost.addTab(tabhost.newTabSpec("1").setIndicator("TAB 1", getResources().getDrawable(R.drawable.icon)).setContent(R.id.text1)); tabhost.setCurrentTab(0);

如果是直接继承Activity类：

 tabhost = (TabHost) findViewById(R.id.tabhost);
 tabhost.setup();
 tabhost.addTab(tabhost.newTabSpec("1" ).setIndicator( "TAB 1" , getResources().getDrawable(R.drawable.icon)).setContent(R.id.text1));
 tabhost.setCurrentTab(0 );

tabhost = (TabHost) findViewById(R.id.tabhost); tabhost.setup(); tabhost.addTab(tabhost.newTabSpec("1").setIndicator("TAB 1", getResources().getDrawable(R.drawable.icon)).setContent(R.id.text1)); tabhost.setCurrentTab(0);

注意加.setup()，否则会有NullPointer的异常

main.xml:

 < TabHost   android:id = "@+id/tabhost"   android:layout_width = "fill_parent"   android:layout_height = "wrap_content" >
     < 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 = "fill_parent"   />
         < FrameLayout   android:id = "@android:id/tabcontent"   android:layout_width = "fill_parent"   android:layout_height = "fill_parent" >
             < TextView   android:id = "@+id/text1"   android:layout_width = "wrap_content"   android:layout_height = "wrap_content"   />
         </ FrameLayout >
     </ LinearLayout >
 </ TabHost >

<TabHost android:id="@+id/tabhost" android:layout_width="fill_parent" android:layout_height="wrap_content"> <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="fill_parent" /> <FrameLayout android:id="@android:id/tabcontent" android:layout_width="fill_parent" android:layout_height="fill_parent"> <TextView android:id="@+id/text1" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </FrameLayout> </LinearLayout> </TabHost>

注意：TabHost标签下的TabWidget和FrameLayout的id 是固定的，分别为"tabs"和"tabcontent"

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动态更改TabHost的选项卡头显示，有两种方法：一种比较笨而且可控性差（为 什么还要讲一会再说），一种比较简单而且可控性高，我们先说简单的那一种：

TabHost本身不提供有效的函数支持对选项卡头的动态更改，但是我们可以通过 TabHost的getTabWidget()函数得到选项卡头的View从而"曲线"更改选项卡头的属性：

 

 ImageView iv = (ImageView) tabhost.getTabWidget().getChildAt(targetLocation).findViewById(android.R.id.icon);
 TextView tv = (TextView) tabhost.getTabWidget().getChildAt(targetLocation).findViewById(android.R.id.title);
 tv.setText("XXXX" );
 iv.setImageDrawable(getResources().getDrawable(R.drawable.icon));

ImageView iv = (ImageView) tabhost.getTabWidget().getChildAt(targetLocation).findViewById(android.R.id.icon); TextView tv = (TextView) tabhost.getTabWidget().getChildAt(targetLocation).findViewById(android.R.id.title); tv.setText("XXXX"); iv.setImageDrawable(getResources().getDrawable(R.drawable.icon)); 其中获得的ImageView即是TabHost的选项卡 头在targetLocation位置的图片的View，TextView是对应的文字的View，这样就可以对它们进行任意的改动了，注意 targetLocation从0开始

还有一种比较笨的方法：

就是自定义TabHost选项卡头的Layout，如下：

 

 tabhost = getTabHost();
 RelativeLayout tempLayout = (RelativeLayout) LayoutInflater.from(this ).inflate(R.layout.mytab,  null );
 TextView targetTabLabel = (TextView) tempLayout.findViewById(R.id.tab_text);
 targetTabLabel.setText("TAB 1" );
 tempLayout.removeAllViews();
 tabhost.addTab(tabhost.newTabSpec("1" ).setIndicator(targetTabLabel).setContent(R.id.text1));

tabhost = getTabHost(); RelativeLayout tempLayout = (RelativeLayout) LayoutInflater.from(this).inflate(R.layout.mytab, null); TextView targetTabLabel = (TextView) tempLayout.findViewById(R.id.tab_text); targetTabLabel.setText("TAB 1"); tempLayout.removeAllViews(); tabhost.addTab(tabhost.newTabSpec("1").setIndicator(targetTabLabel).setContent(R.id.text1));

注意要对tempLayout使用removeAllViews()，否则在将 targetTabLabel加入TabHost中时会出现java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.的异常

其中R.layout.mytab来自mytab.xml:

 <? xml   version = "1.0"   encoding = "utf-8" ?>
 < RelativeLayout   xmlns:android = "http://schemas.android.com/apk/res/android"
     android:layout_width = "wrap_content"
     android:layout_height = "wrap_content" >
 < TextView   android:id = "@+id/tab_text"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content"
         android:gravity = "center"
         android:textStyle = "bold"
         android:background = "@drawable/selector_img" />
 </ RelativeLayout >

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content"> <TextView android:id="@+id/tab_text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center" android:textStyle="bold" android:background="@drawable/selector_img"/> </RelativeLayout>
其中android:text="@drawable/selector_img"指向 selector_img.xml:

 

 <? xml   version = "1.0"   encoding = "utf-8" ?>
 < selector   xmlns:android = "http://schemas.android.com/apk/res/android" >
 < item   android:state_selected = "false"
       android:drawable = "@drawable/img1" >
 </ item >
 < item   android:state_selected = "true"
       android:drawable = "@drawable/img2" >
 </ item >
 </ selector >

<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:state_selected="false" android:drawable="@drawable/img1"> </item> <item android:state_selected="true" android:drawable="@drawable/img2"> </item> </selector>
点击时使用Selector置换背景图片，文字的更改尚未用此方法验证，这种方法非常繁琐而且可控性太差，只能响应选择事件，且只能更改2个选项，但是之 所以讲解这种方法，是因为这里顺便讲解了如何自定义TabHost选项卡头的Layout，如果你想在UI上做出更多的花样，这个技巧是很有帮助的。