Android的PackageManager类用于检索目前安装在设备上的应用软件包的信息。你可以通过调用getpackagemanager()得到PackageManager类的一个实例。对查询和操作安装包和相关的权限提供了方法，在下面这个Android的例子中，我们得到了在Android安装的应用程序列表。
PackageManager packageManager = getPackageManager();
List list = packageManager.getInstalledApplications(PackageManager.GET_META_DATA)
packageManager.getInstalledApplications()返回一个列表都是安装在设备上的应用程序包。如果我们把 flag GET_UNINSTALLED_PACKAGES设定，一个列表中的所有应用，包括那些设置为dont_delete_data(部分已安装的应用程序的数据目录)将返回。
1.创建 布局文件
activity_main.xml
你可以看到附件中的截图，我们将创建一个列表显示所有已安装的应用程序。
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
snippet_list_row.xml
这个布局是由ListView适配器用于表示应用程序的细节。它显示应用程序图标、应用程序名称和应用程序包。
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
android:id="@+id/app_icon"
android:layout_width="50dp"
android:layout_height="50dp"
android:padding="3dp"
android:scaleType="centerCrop" />
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_vertical"
android:orientation="vertical"
android:paddingLeft="5dp" >
android:id="@+id/app_name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:textStyle="bold" />
android:id="@+id/app_paackage"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical" />
2.java 类
AllAppsActivity.java
这是用于初始化和列表已安装的应用程序的主要应用程序类。从packagemanage得到应用细节列表是一个耗时的任务，我们将在AsyncTask里面做。同时，类使用自定义适配器“自定义listview applicationadapter”。
package com.javatechig.listapps;
import java.util.ArrayList;
import java.util.List;
import android.app.AlertDialog;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.ActivityNotFoundException;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;
public class AllAppsActivity extends ListActivity {
private PackageManager packageManager = null;
private List applist = null;
private ApplicationAdapter listadaptor = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
packageManager = getPackageManager();
new LoadApplications().execute();
}
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
boolean result = true;
switch (item.getItemId()) {
case R.id.menu_about: {
displayAboutDialog();
break;
}
default: {
result = super.onOptionsItemSelected(item);
break;
}
}
return result;
}
private void displayAboutDialog() {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle(getString(R.string.about_title));
builder.setMessage(getString(R.string.about_desc));
builder.setPositiveButton("Know More", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://stacktips.com"));
startActivity(browserIntent);
dialog.cancel();
}
});
builder.setNegativeButton("No Thanks!", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
builder.show();
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
ApplicationInfo app = applist.get(position);
try {
Intent intent = packageManager
.getLaunchIntentForPackage(app.packageName);
if (null != intent) {
startActivity(intent);
}
} catch (ActivityNotFoundException e) {
Toast.makeText(AllAppsActivity.this, e.getMessage(),
Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(AllAppsActivity.this, e.getMessage(),
Toast.LENGTH_LONG).show();
}
}
private List checkForLaunchIntent(List list) {
ArrayList applist = new ArrayList();
for (ApplicationInfo info : list) {
try {
if (null != packageManager.getLaunchIntentForPackage(info.packageName)) {
applist.add(info);
}
} catch (Exception e) {
e.printStackTrace();
}
}
return applist;
}
private class LoadApplications extends AsyncTask {
private ProgressDialog progress = null;
@Override
protected Void doInBackground(Void... params) {
applist = checkForLaunchIntent(packageManager.getInstalledApplications(PackageManager.GET_META_DATA));
listadaptor = new ApplicationAdapter(AllAppsActivity.this,
R.layout.snippet_list_row, applist);
return null;
}
@Override
protected void onCancelled() {
super.onCancelled();
}
@Override
protected void onPostExecute(Void result) {
setListAdapter(listadaptor);
progress.dismiss();
super.onPostExecute(result);
}
@Override
protected void onPreExecute() {
progress = ProgressDialog.show(AllAppsActivity.this, null,
"Loading application info...");
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
}
}
ApplicationAdapter.java
package com.javatechig.listapps;
import java.util.List;
import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class ApplicationAdapter extends ArrayAdapter {
private List appsList = null;
private Context context;
private PackageManager packageManager;
public ApplicationAdapter(Context context, int textViewResourceId,
List appsList) {
super(context, textViewResourceId, appsList);
this.context = context;
this.appsList = appsList;
packageManager = context.getPackageManager();
}
@Override
public int getCount() {
return ((null != appsList) ? appsList.size() : 0);
}
@Override
public ApplicationInfo getItem(int position) {
return ((null != appsList) ? appsList.get(position) : null);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
if (null == view) {
LayoutInflater layoutInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = layoutInflater.inflate(R.layout.snippet_list_row, null);
}
ApplicationInfo applicationInfo = appsList.get(position);
if (null != applicationInfo) {
TextView appName = (TextView) view.findViewById(R.id.app_name);
TextView packageName = (TextView) view.findViewById(R.id.app_paackage);
ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);
appName.setText(applicationInfo.loadLabel(packageManager));
packageName.setText(applicationInfo.packageName);
iconview.setImageDrawable(applicationInfo.loadIcon(packageManager));
}
return view;
}
};
