TabHost的自定义

        使用自定义的TabHost可以不用继承TabActicity，但是要注意的是如果使用Activity作为Content的话，有两处代码是一定要加的。不然就会出现RuntimeError，还有在XML布局中使用自定义的TabHost时除了TabHost的id自定义外，LinearLayout和TabWidget的id必须使用系统默认。具体可参考下面的Demo。
使用TabWidget的效果（左）和自定义View的效果图（右）：
       
MainActivity加载的XML布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context=".MainActivity" >



    <TabHost

        android:id="@+id/tabhost"

        android:layout_width="match_parent"

        android:layout_height="match_parent" >



        <LinearLayout

            android:layout_width="match_parent"

            android:layout_height="match_parent"

            android:orientation="vertical" >



            <TabWidget

                android:id="@android:id/tabs"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"

                android:layout_weight="0" />



            <FrameLayout

                android:id="@android:id/tabcontent"

                android:layout_width="match_parent"

                android:layout_height="0dip"

                android:layout_weight="1" />

        </LinearLayout>

    </TabHost>



</RelativeLayout>

MainActivity的Java代码（注意红色代码）：

package com.hitech.tabhostdemo;



import android.app.Activity;

import android.app.LocalActivityManager;

import android.content.Intent;

import android.os.Bundle;

import android.view.Menu;

import android.widget.TabHost;

import android.widget.TabHost.TabSpec;



@SuppressWarnings("deprecation")

public class MainActivity extends Activity {



    private LocalActivityManager lam; 

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);



        TabHost tabHost = (TabHost) findViewById(R.id.tabhost);



        // Intent对象

        Intent intent1 = new Intent(this, TabSpecActivity1.class);

        Intent intent2 = new Intent(this, TabSpecActivity2.class);

        Intent intent3 = new Intent(this, TabSpecActivity3.class);



        // TabSpec对象

        TabSpec tabSpec1 = tabHost.newTabSpec("first");

        tabSpec1.setIndicator("第一页",

                getResources().getDrawable(android.R.drawable.ic_dialog_email));

        tabSpec1.setContent(intent1);



        TabSpec tabSpec2 = tabHost.newTabSpec("second");

        tabSpec2.setIndicator("第二页",

                getResources().getDrawable(android.R.drawable.ic_btn_speak_now));

        tabSpec2.setContent(intent2);



        TabSpec tabSpec3 = tabHost.newTabSpec("third");

        tabSpec3.setIndicator("第三页",

                getResources().getDrawable(android.R.drawable.ic_dialog_dialer));

        tabSpec3.setContent(intent3);



        lam = new LocalActivityManager(this, false); lam.dispatchCreate(savedInstanceState); tabHost.setup(lam); 

        tabHost.addTab(tabSpec1);

        tabHost.addTab(tabSpec2);

        tabHost.addTab(tabSpec3);



        // TabActivity

    }



    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.

        getMenuInflater().inflate(R.menu.activity_main, menu);

        return true;

    }



    @Override protected void onPause() { super.onPause(); lam.dispatchPause(isFinishing()); } }

自定义View代替TabWidget效果的实现原理：隐藏TabWidget，然后在线性布局中加入自定义View，如上图中即为LinearLayout中添加三个TextView，再分别对TextView设置点击事件来模拟TabWidget的效果。
同样，MainActivity加载的XML布局如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context=".MainActivity" >



    <TabHost

        android:id="@+id/tabhost"

        android:layout_width="match_parent"

        android:layout_height="match_parent" >



        <LinearLayout

            android:layout_width="match_parent"

            android:layout_height="match_parent"

            android:orientation="vertical" >



            <TabWidget

                android:id="@android:id/tabs"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"

                android:layout_weight="0"

                android:orientation="horizontal"android:visibility="gone" />



            <FrameLayout

                android:id="@android:id/tabcontent"

                android:layout_width="match_parent"

                android:layout_height="0dip"

                android:layout_weight="1" />



            <View

                android:layout_width="match_parent"

                android:layout_height="1dp"

                android:layout_marginBottom="1dp"

                android:background="@android:color/background_light" />



            <LinearLayout android:layout_width="match_parent"

                android:layout_height="wrap_content" >



                <TextView

                    android:id="@+id/tab_convst"

                    android:layout_width="0dp"

                    android:layout_height="wrap_content"

                    android:layout_weight="1"

                    android:drawablePadding="-10dp"

                    android:drawableTop="@drawable/ic_widget_conversation"

                    android:gravity="center"

                    android:paddingBottom="5dp"

                    android:text="@string/conversation" />



                <TextView

                    android:id="@+id/tab_folder"

                    android:layout_width="0dp"

                    android:layout_height="wrap_content"

                    android:layout_weight="1"

                    android:drawablePadding="-10dp"

                    android:drawableTop="@drawable/ic_widget_folder"

                    android:gravity="center"

                    android:paddingBottom="5dp"

                    android:text="@string/folder" />



                <TextView

                    android:id="@+id/tab_group"

                    android:layout_width="0dp"

                    android:layout_height="wrap_content"

                    android:layout_weight="1"

                    android:drawablePadding="-10dp"

                    android:drawableTop="@drawable/ic_widget_group"

                    android:gravity="center"

                    android:paddingBottom="5dp"

                    android:text="@string/group" />

            </LinearLayout>

        </LinearLayout>

    </TabHost>



</RelativeLayout>

注意和以往不同之处已做标记，分别是TabWidget和自定义的LinearLayout。
MainActivity中的处理：

package com.hitech.capacitymessage;



import android.app.Activity;

import android.app.LocalActivityManager;

import android.content.Intent;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.TabHost;

import android.widget.TabHost.TabSpec;

import android.widget.TextView;



@SuppressWarnings("deprecation")

public class MainActivity extends Activity implements OnClickListener {



    private static final String TAG = "MainActivity";

    private LocalActivityManager lam;

    private TabHost tabHost;

    private Bundle state;

    private TabSpec tab1;

    private TabSpec tab2;

    private TabSpec tab3;



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        this.state = savedInstanceState;

        activityInitializer();

    }



    private void activityInitializer() {

        tabHost = (TabHost) findViewById(R.id.tabhost);

        tab1 = tabHost.newTabSpec("tab1");

        tab1.setIndicator("会话",

                getResources().getDrawable(R.drawable.ic_widget_conversation));

        tab1.setContent(new Intent(this, TabActivity1.class));



        tab2 = tabHost.newTabSpec("tab2");

        tab2.setIndicator("文件夹",

                getResources().getDrawable(R.drawable.ic_widget_folder));

        tab2.setContent(new Intent(this, TabActivity2.class));



        tab3 = tabHost.newTabSpec("tab3");

        tab3.setIndicator("群组",

                getResources().getDrawable(R.drawable.ic_widget_group));

        tab3.setContent(new Intent(this, TabActivity3.class));



        lam = new LocalActivityManager(this, true);

        lam.dispatchCreate(state);

        tabHost.setup(lam);



        tabHost.addTab(tab1);

        tabHost.addTab(tab2);

        tabHost.addTab(tab3);



        TextView block1 = (TextView) findViewById(R.id.tab_convst);

        TextView block2 = (TextView) findViewById(R.id.tab_folder);

        TextView block3 = (TextView) findViewById(R.id.tab_group);



        block1.setOnClickListener(this);

        block2.setOnClickListener(this);

        block3.setOnClickListener(this);

    }



    @Override

    public void onClick(View v) {

        String tabTag = tabHost.getCurrentTabTag();

        switch (v.getId()) {

        case R.id.tab_convst:

            if (!tabTag.equals("tab1")) {

                tabHost.setCurrentTabByTag("tab1");

            }

            Log.e(TAG, tabHost.getCurrentTabTag());

            break;

        case R.id.tab_folder:

            if (!tabTag.equals("tab2")) {

                tabHost.setCurrentTabByTag("tab2");

            }

            Log.e(TAG, tabHost.getCurrentTabTag());

            break;

        case R.id.tab_group:

            if (!tabTag.equals("tab3")) {

                tabHost.setCurrentTabByTag("tab3");

            }

            Log.e(TAG, tabHost.getCurrentTabTag());

            break;

        default:

            break;

        }

    }



    @Override

    protected void onPause() {

        super.onPause();

        lam.dispatchPause(isFinishing());

    }

}