Android Launcher--简易Launcher开发

 第一步，把我们的应用程序作为home（即实现按下home键，启动自己的launcher.）

要把我们的应用程序作为home，只需要在AndroidManifest.xml中添加：
 
 

AndroidManifest.xml

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

< application android:icon = " @drawable/icon " android:label = " @string/app_name " >
< activity android:name = " .MyHome "
android:label = " @string/app_name " >
< intent - filter >
< action android:name = " android.intent.action.MAIN " />
< category android:name = " android.intent.category.LAUNCHER " />
< category android:name = " android.intent.category.HOME " />
< category android:name = " android.intent.category.DEFAULT " />
intent - filter >
activity >

application >
manifest >

第二步，列出安装的应用程序

列出已经安装的应用程序是作为launcher比不可少的功能。下面我们就讲解怎样将应用程序列出来。程序运行后的样子如下：

1. 修改main.xml，在其中添加一个GridView用来显示应用程序列表。

main.xml

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

< GridView android:layout_width = " match_parent "
android:id = " @+id/apps_list "
android:numColumns = " 4 "
android:layout_height = " wrap_content " >
GridView >

LinearLayout

2 . 通过PackageManager的api 查询已经安装的apk

private void loadApps() {
Intent mainIntent = new Intent(Intent.ACTION_MAIN, null );
mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

mApps = getPackageManager().queryIntentActivities(mainIntent, 0 );
}

3. 实现用于显示Gridview的Adapter，使其显示获得的应用程序列表

View Code

public class AppsAdapter extends BaseAdapter {
public AppsAdapter() {
}

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


if (convertView == null ) {
i = new ImageView(MyHome. 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;
}

4.监听GridView的onItemClick事件

设置一个监听器是为了当gridView的某项被点击时，会有一个回调函数通知我们。
我们调用mGrid.setOnItemClickListener(listener); 设置一个监听器
mGrid.setOnItemClickListener(listener)中的listener是一个接口，其类型为：android.widget.AdapterView.OnItemClickListener

private OnItemClickListener listener = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView parent, View view, int position, long id) {
// 事件内容....
}
};

5.启动被点击应用的activity

一般来讲，我们根据position即可知道被点击的项目是哪一项了。现在我们根据被点击的项目，取出对应的应用程序数据（主要是其中的主activity），然后启动activity。用下面代码实现：

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);
}

最后整个Activity的代码如下：

MyHome.java

package org.bangchui.myhome;

import java.util.List;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemClickListener;

public class MyHome 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);
        }

    };

     /** Called when the activity is first created. */
    @Override
     public void onCreate(Bundle savedInstanceState) {
         super .onCreate(savedInstanceState);

        loadApps();
        setContentView(R.layout.main);
        mGrid = (GridView) findViewById(R.id.apps_list);
        mGrid.setAdapter( new AppsAdapter());

        mGrid.setOnItemClickListener(listener);
    }


     private void loadApps() {
        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null );
        mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

        mApps = getPackageManager().queryIntentActivities(mainIntent, 0 );
    }

     public class AppsAdapter extends BaseAdapter {
         public AppsAdapter() {
        }

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

             if (convertView == null ) {
                i = new ImageView(MyHome. 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;
        }
    }
}

转载于:https://www.cnblogs.com/playing/archive/2011/04/13/2014705.html