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<ApplicationInfo> list = packageManager.getInstalledApplications(PackageManager.GET_META_DATA)
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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。

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"android:orientation="vertical" ><ListViewandroid:id="@android:id/list"android:layout_width="fill_parent"android:layout_height="wrap_content" /></LinearLayout>
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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。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="wrap_content" ><ImageViewandroid:id="@+id/app_icon"android:layout_width="50dp"android:layout_height="50dp"android:padding="3dp"android:scaleType="centerCrop" /><LinearLayoutandroid:layout_width="fill_parent"android:layout_height="fill_parent"android:gravity="center_vertical"android:orientation="vertical"android:paddingLeft="5dp" ><TextViewandroid:id="@+id/app_name"android:layout_width="fill_parent"android:layout_height="wrap_content"android:gravity="center_vertical"android:textStyle="bold" /><TextViewandroid:id="@+id/app_paackage"android:layout_width="fill_parent"android:layout_height="wrap_content"android:gravity="center_vertical" /></LinearLayout></LinearLayout>
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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<ApplicationInfo> applist = null;private ApplicationAdapter listadaptor = null;@Overridepublic 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();}@Overrideprotected 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<ApplicationInfo> checkForLaunchIntent(List<ApplicationInfo> list) {ArrayList<ApplicationInfo> applist = new ArrayList<ApplicationInfo>();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<Void, Void, Void> {private ProgressDialog progress = null;@Overrideprotected 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;}@Overrideprotected void onCancelled() {super.onCancelled();}@Overrideprotected void onPostExecute(Void result) {setListAdapter(listadaptor);progress.dismiss();super.onPostExecute(result);}@Overrideprotected void onPreExecute() {progress = ProgressDialog.show(AllAppsActivity.this, null,"Loading application info...");super.onPreExecute();}@Overrideprotected void onProgressUpdate(Void... values) {super.onProgressUpdate(values);}}
}
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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<ApplicationInfo> {private List<ApplicationInfo> appsList = null;private Context context;private PackageManager packageManager;public ApplicationAdapter(Context context, int textViewResourceId,List<ApplicationInfo> appsList) {super(context, textViewResourceId, appsList);this.context = context;this.appsList = appsList;packageManager = context.getPackageManager();}@Overridepublic int getCount() {return ((null != appsList) ? appsList.size() : 0);}@Overridepublic ApplicationInfo getItem(int position) {return ((null != appsList) ? appsList.get(position) : null);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic 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;}
};
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