android之Tabhost深入讲解一

大家都知道Tabhost中Tabwidget的布局是图标在上，文字在下的垂直布局。比如通讯录的布局。

这种布局在手机上的竖屏上用得最多，但在横屏则显得水平分布得不够紧凑。如何实现自定义的布局呢？

1：首先理解Tabhost的布局：

<?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="0dip"
			android:layout_weight="1">
		</FrameLayout>
	</LinearLayout>
</TabHost>

 TabHost里面包含了一个<LinearLayout>,然后LinearLayout里面有一个TabWidget 这个存放每个“切换卡”，FrameLayout里面存放每个切换卡下面的内容，

TabWidget 理解：  
1. TabWidget 为 horizontal 的 LinearLayout  
2. 且 其包含的标签又是一个RelativeLayout  
3. 每个标签RelativeLayout 里面包含2个View: TextView ImageView 
有了这个理解，可以估计得到

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<RelativeLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">
    <ImageView  />
    <TextView  />
</RelativeLayout>
<RelativeLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">
    <ImageView  />
    <TextView  />
</RelativeLayout>
..........多个RelativeLayout 
</LinearLayout> 

 有了这个布局，就可以自定义自己的布局了，以图片在左，文字在右为例。

package com.android.customtabhost;

import android.app.TabActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TabHost;
import android.widget.TabWidget;
import android.widget.TextView;

public class CustomTabHost extends TabActivity  {

	
    private TabHost mTabHost;
    private static final String TAB_SETTING_TAG_0 = "tab_setting0";
    private static final String TAB_SETTING_TAG_1 = "tab_setting1";    
    private static final String TAB_SETTING_TAG_2 = "tab_setting2";
    
	/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        //setContentView(R.layout.main);

        mTabHost = getTabHost();
        
        // Setup the tabs
        setupSettingTab(TAB_SETTING_TAG_0, 0);     
        setupSettingTab(TAB_SETTING_TAG_1, 1);  
        setupSettingTab(TAB_SETTING_TAG_2, 2);  
    }
    
    private void setupSettingTab(String tag, int num) {
        // TODO Auto-generated method stub
        // Force the class since overriding tab entries doesn't work
        Intent intent = new Intent();
        intent.setClass(this, SettingActivity.class);

        String name = getResources().getString(R.string.setting);
        mTabHost.addTab(mTabHost.newTabSpec(tag).setIndicator("")
                        .setContent(intent));

        addToTabHost(name, R.drawable.setting_background, num);

    }
    
    private void addToTabHost(String name, int image, int number) {
        // TODO Auto-generated method stub
        LinearLayout ll = (LinearLayout) mTabHost.getChildAt(0);
        TabWidget tw = (TabWidget) ll.getChildAt(0);
        RelativeLayout rl = (RelativeLayout) tw.getChildAt(number);

        rl.addView(composeLayout(name, image), new LinearLayout.LayoutParams(
                       LinearLayout.LayoutParams.FILL_PARENT,
                       LinearLayout.LayoutParams.FILL_PARENT));
    }

    private View composeLayout(String name, int image) {
        LinearLayout layout = new LinearLayout(this);
        layout.setGravity(Gravity.CENTER);
        layout.setOrientation(LinearLayout.HORIZONTAL);

        ImageView iv = new ImageView(this);
        iv.setImageResource(image);
        layout.addView(iv, new LinearLayout.LayoutParams(
                           LinearLayout.LayoutParams.WRAP_CONTENT,
                           LinearLayout.LayoutParams.FILL_PARENT));

        TextView tv = new TextView(this);
        tv.setGravity(Gravity.CENTER);
        tv.setSingleLine(true);
        tv.setPadding(10, 0, 0, 0);
        tv.setTextSize(18);
        tv.setText(name);
        layout.addView(tv, new LinearLayout.LayoutParams(
                           LinearLayout.LayoutParams.WRAP_CONTENT,
                           LinearLayout.LayoutParams.FILL_PARENT));

        return layout;
    }
}