美团(五)TabHost实现主界面

xml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="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <TabWidget
            android:id="@android:id/tabs"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:layout_alignParentBottom="true"
            android:background="#ededed" />

        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_above="@android:id/tabs" />
    </RelativeLayout>

</TabHost>

package com.myandroid.meituan;

import android.app.TabActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.ImageView;
import android.widget.TabHost;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.TabHost.TabSpec;

public class MyMeiTuanTabActivity extends TabActivity {
	private Context context;
	private View view;
	private static final int TG_TYPE = 0;
	private static final int SJ_TYPE = 1;
	private static final int WD_TYPE = 2;
	private static final int GD_TYPE = 3;
    private  long exitTime=0;
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_tab_meituan);
		
		 //启动activity时不自动弹出软键盘
        getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
		context = this;
		TabHost tabhost = getTabHost();

		TabSpec tabSpec1 = tabhost.newTabSpec("tab1");
		tabSpec1.setIndicator(createIndcatorView(TG_TYPE));
		tabSpec1.setContent(new Intent(context, MeiTuanTuanGouActivity.class));

		TabSpec tabSpec2 = tabhost.newTabSpec("tab2");
		tabSpec2.setIndicator(createIndcatorView(SJ_TYPE));
		tabSpec2.setContent(new Intent(context, MeiTuanMerchantActivity.class));

		TabSpec tabSpec3 = tabhost.newTabSpec("tab3");
		tabSpec3.setIndicator(createIndcatorView(WD_TYPE));
		tabSpec3.setContent(new Intent(context, MeiTuanMineActicity.class));

		TabSpec tabSpec4 = tabhost.newTabSpec("tab4");
		tabSpec4.setIndicator(createIndcatorView(GD_TYPE));
		tabSpec4.setContent(new Intent(context,MeiTuanMroeActivity.class));

		tabhost.addTab(tabSpec1);
		tabhost.addTab(tabSpec2);
		tabhost.addTab(tabSpec3);
		tabhost.addTab(tabSpec4);
	}
	/**
	 *返回键处理，按两次退出程序 
	 */
	public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(keyCode==KeyEvent.KEYCODE_BACK){
			if ((System.currentTimeMillis() - exitTime)> 2000) {
    			Toast.makeText(getApplicationContext(), "再按一次退出程序",
    					Toast.LENGTH_SHORT).show();
    			exitTime = System.currentTimeMillis();
    		} else {
    			MyMeiTuanTabActivity.this.finish();
    			System.exit(0);
    		}
			return false;
        	
        }
   	return super.onKeyDown(keyCode, event);
    }
	/**
	 * 
	 * @param tab
	 * @return
	 */
	public View createIndcatorView(int tab) {
		view = LayoutInflater.from(context).inflate(R.layout.tab_meituan, null);
		TextView textview = (TextView) view
				.findViewById(R.id.meituan_tab_textview);
		ImageView imageicon = (ImageView) view
				.findViewById(R.id.meituan_tab_imageview);

		switch (tab) {
		case TG_TYPE:
			textview.setText("团购");
			imageicon
					.setImageResource(R.drawable.selector_drawable_select_tuangou);
			break;
		case SJ_TYPE:
			textview.setText("商家");
			imageicon
					.setImageResource(R.drawable.selector_drawable_select_shangjia);
			break;
		case WD_TYPE:
			textview.setText("我的");
			imageicon
					.setImageResource(R.drawable.selector_drawable_select_wode);
			break;
		case GD_TYPE:
			textview.setText("更多");
			imageicon
					.setImageResource(R.drawable.selector_drawable_select_more);
			break;

		}
		return view;
	}
}

这里我们主要要实现的是主界面底部的四个页卡功能，有的APP的页卡在顶部，不管在顶部还是底部，都要用TabHost,上面我们设置android:layout_alignParentBottom="true"
所以在底部，也可以设置为在顶部，在xml文件中的每个id都是用的系统的id。<TabWidget为页卡区,<FrameLayout为内容区。