android 实现home键启动并半透明程序背景效果显示全部应用程序

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.Translucent"  >
        <activity
            android:name="com.example.myapp.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
				<category android:name="android.intent.category.HOME" />
                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:id="@+id/relaGrid"
  android:gravity="center_horizontal"
  android:layout_width="80dp"
  android:paddingTop="5dp"
  android:layout_height="100dp">
  <ImageView
  	android:id="@+id/ivAppIcon"
  	android:scaleType="fitCenter"
  	android:layout_gravity="center_horizontal|top"
  	android:layout_width="48dp"
  	android:layout_height="48dp" />
  <TextView
  	android:id="@+id/tvAppName"
  	android:layout_width="74dp"
  	android:ellipsize="marquee"
  	android:textColor="#FFFF"
  	android:layout_height="50dp"
  	android:gravity="center_horizontal|center_vertical" />
</LinearLayout>

package com.example.myapp;


import java.util.List;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {
	private List<ResolveInfo> mApps;
	GridView mGrid;
	
	private OnItemClickListener listener = new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,long id) {
            ResolveInfo info = mApps.get(position);
            
            //该应用的包名
            String pkg = info.activityInfo.packageName;
            //应用的主activity类
            String cls = info.activityInfo.name;
            
            ComponentName componet = new ComponentName(pkg, cls);
            
            Intent i = new Intent();
            i.setComponent(componet);
            startActivity(i);
        }

    };
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
		loadApps();
		setContentView(R.layout.activity_main);
		mGrid = (GridView)findViewById(R.id.apps_list);
		mGrid.setBackgroundColor(0xcc00cc00);
		mGrid.setAdapter(new ImageAdapter(this));
		mGrid.setOnItemClickListener(listener);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		getMenuInflater().inflate(R.menu.main, menu);
		
		return true;
	}
	
	private void loadApps(){
		Intent mainIntent = new Intent(Intent.ACTION_MAIN,null);
		mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
		mApps = getPackageManager().queryIntentActivities(mainIntent,0);	
	}
	

	

	private class ImageAdapter extends BaseAdapter {  
		private LayoutInflater mInflater;  
		  
        public ImageAdapter(Context context) {  
        	this.mInflater = LayoutInflater.from(context);
        }  
        /** 
         * 获取当前Adapter的Items数目 
         */  
        public int getCount() {  
            return mApps.size();  
        }  
        /** 
         * 获取相应position的Item 
         */  
        public Object getItem(int position) {  
            return mApps.get(position); 
        }  
        /** 
         * 获取相应position的Item在List中的row id 
         */  
        public long getItemId(int position) {  
            return position;  
        }  
        /** 
         *  position就是位置从0开始 
         *  convertView是GridView每一项要显示的内容，也就是  R.layout.app_item中所定义的布局 
         *  parent就是父窗体GridView  
         */  
          
        public View getView(int position, View convertView, ViewGroup parent) {  
        	System.out.println("==Pos:"+position);
            ViewHolder holder;  
            if (convertView == null) {  
            	
                convertView = mInflater.inflate(R.layout.app_item, null);  
                holder = new ViewHolder();                
                holder.text = (TextView) convertView.findViewById(R.id.tvAppName);  
                holder.icon = (ImageView) convertView.findViewById(R.id.ivAppIcon);  
                convertView.setTag(holder);  
            } else {  
                holder = (ViewHolder) convertView.getTag();  
            }  
            ResolveInfo info = mApps.get(position);
            //holder.text.setTextColor(android.graphics.Color.BLUE);
            holder.text.setText(info.activityInfo.loadLabel(getPackageManager()));  
            holder.icon.setImageDrawable(info.activityInfo.loadIcon(getPackageManager()));  
            return convertView;  
        }  
        class ViewHolder {  
            TextView text;  
            ImageView icon;  
        }  
    } 
	
	public class AppsAdapter extends BaseAdapter {
        public AppsAdapter() {
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView i;

            if (convertView == null) {
                i = new ImageView(MainActivity.this);
                i.setScaleType(ImageView.ScaleType.FIT_CENTER);
                i.setLayoutParams(new GridView.LayoutParams(50, 50));
            } else {
                i = (ImageView) convertView;
            }

            ResolveInfo info = mApps.get(position);
            i.setImageDrawable(info.activityInfo.loadIcon(getPackageManager()));

            return i;
        }

        public final int getCount() {
            return mApps.size();
        }

        public final Object getItem(int position) {
            return mApps.get(position);
        }

        public final long getItemId(int position) {
            return position;
        }
	}
        
	
        

}