android得到已安装和未安装apk的信息

         在获取apk资源时候最重要的一个类就是PackageManager，我们可以通过这个类得到各种想要的东西，首先是得到已经安装的apk的基本信息，包括label，和图标等资源：

PackageManager pm = getPackageManager();
List<PackageInfo> apkInfos = pm.getInstalledPackages(0);
ArrayList<String> infos_name =  new ArrayList<String>() ;//用来存放label
ArrayList<Drawable> infos_icon = newArrayList<Drawable>();//用来存储apk启动图标资源
String name = "";
   Drawable icon;
   PackageInfo apk;
   for (int i = 0; i < apkInfos.size(); )
   {
      apk = apkInfos.get(i);
      i++;
      name = (String) pm.getApplicationLabel(apk.applicationInfo);
      icon = pm.getApplicationIcon(apk.applicationInfo);
      infos_icon.add(icon);
      infos_name.add(name);
   }

List<PackageInfo>packagesInfo =  pm.getInstalledPackages(0);
for (PackageInfo packageInfo : packagesInfo) {
	Log.d("TAG","packageInfo NAME IS :"+packageInfo.packageName);
}


PackageManager pm = getPackageManager();
try {   
//获得com.example.pertest包中的activity，service和broadcastreceiver
PackageInfo packageInfo = pm.getPackageInfo("com.example.pertest",
				PackageManager.GET_PERMISSIONS
						| PackageManager.GET_SERVICES
						| PackageManager.GET_RECEIVERS);
	ActivityInfo[] activities = packageInfo.activities;

	if (activities != null) {
		for (ActivityInfo activityInfo : activities) {
			Log.d("TAG", "the activity " + activityInfo.toString()
					+ "==" + packageInfo.versionCode + "==="
					+ packageInfo.versionName);
		}
	} else {
		Log.d("TAG", "the activity is null");
	}
	ServiceInfo[] serviceInfos = packageInfo.services;
	for (ServiceInfo serviceInfo : serviceInfos) {
		Log.d("TAG", "service name is :" + serviceInfo.name);
	}

	activities = packageInfo.receivers;
	for (ActivityInfo activity : activities) {
		Log.d("TAG", "receiver is :" + activity.name);
	}
} catch (NameNotFoundException e) {
	// TODO Auto-generated catch block
	e.printStackTrace();
}

得到未安装apk的图标：

public static Drawable getAppIcon(Context context, String apkFilepath) {
        PackageManager pm = context.getPackageManager();
        PackageInfo pkgInfo = getPackageInfo(context, apkFilepath);
        if (pkgInfo == null) {
            return null;
        }

        ApplicationInfo appInfo = pkgInfo.applicationInfo;
        if (Build.VERSION.SDK_INT >= 8) {
            appInfo.sourceDir = apkFilepath;
            appInfo.publicSourceDir = apkFilepath;
        }
        return pm.getApplicationIcon(appInfo);
    }

public static CharSequence getAppLabel(Context context, String apkFilepath) {
        PackageManager pm = context.getPackageManager();
        PackageInfo pkgInfo = getPackageInfo(context, apkFilepath);
        if (pkgInfo == null) {
            return null;
        }
        ApplicationInfo appInfo = pkgInfo.applicationInfo;
        if (Build.VERSION.SDK_INT >= 8) {
            appInfo.sourceDir = apkFilepath;
            appInfo.publicSourceDir = apkFilepath;
        }

        return pm.getApplicationLabel(appInfo);
 }

//得到PackageInfo对象，其中包含了该apk包含的activity和service
public static PackageInfo getPackageInfo(Context context, String apkFilepath) {
        PackageManager pm = context.getPackageManager();
        PackageInfo pkgInfo = null;
        try {
            pkgInfo = pm.getPackageArchiveInfo(apkFilepath, PackageManager.GET_ACTIVITIES | PackageManager.GET_SERVICES);
        } catch (Exception e) {
            // should be something wrong with parse
            e.printStackTrace();
        }
        return pkgInfo;
    }

String mNativeLibDir = mContext.getDir("pluginlib", Context.MODE_PRIVATE).getAbsolutePath();
 private DexClassLoader createDexClassLoader(String dexPath) {
        File dexOutputDir = mContext.getDir("dex", Context.MODE_PRIVATE);
        dexOutputPath = dexOutputDir.getAbsolutePath();
        DexClassLoader loader = new DexClassLoader(dexPath, dexOutputPath, mNativeLibDir, mContext.getClassLoader());
        return loader;
 }

   第二个参数dexOutPath就是该apk文件对应的dex文件的存放路径，不可以为null。

   第三个参数是目标类中使用的C/C++库的列表,每个目录用File.pathSeparator间隔开; 可以为 null。

  第四个参数是该类装载器的父装载器，一般用当前执行类的装载器。

在获得了该DexClassLoader对象以后，我们就可以实现动态加载该apk中的方法了，详细的方法，请看我的另一篇文章：android动态加载

对于加载未安装的apk中的资源，由于使用的是不同的context，所以，这里先这样做：

 private AssetManager createAssetManager(String dexPath) {
        try {
            AssetManager assetManager = AssetManager.class.newInstance();
            Method addAssetPath = assetManager.getClass().getMethod("addAssetPath", String.class);
            addAssetPath.invoke(assetManager, dexPath);
            return assetManager;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }


private Resources createResources(AssetManager assetManager) {
        Resources superRes = mContext.getResources();
        Resources resources = new Resources(assetManager, superRes.getDisplayMetrics(), superRes.getConfiguration());
        return resources;
}