(原)android4.2以后获取应用程序和缓存大小的方法（源码有改变）

以前获取应用的大小是用

PackageManager mPackageManager= getPackageManager();

try {Method getPackageSizeInfoMethod = PackageManager.class.getDeclaredMethod("getPackageSizeInfo", String.class,
              IPackageStatsObserver.class);
getPackageSizeInfoMethod.invoke(mPackageManager, packageInfo.packageName,new MyObserver());
} catch (Exception e) {
}

class MyObserver extends IPackageStatsObserver.Stub {  

    @Override
    public void onGetStatsCompleted(PackageStats pStats, boolean succeeded)
            throws RemoteException {
        long cacheSize = pStats.cacheSize;
        String packageName = pStats.packageName;
        String formatFileSize = Formatter.formatFileSize(
                getApplicationContext(), cacheSize);
        System.out.println(packageName + ":" + formatFileSize);
    }
}

但在4.2后 PackageManager.getPackageSizeInfo(String packageName, IPackageStatsObserver observer)不可用，

改为PackageManager.getPackageSizeInfo(String packageName, int userHandle, IPackageStatsObserver observer),

至于增加的参数userHandle的解释是：The user whose size information should be retrieved。

这个userHandle怎么来？ 通过系统类的UserHandle.myUserId()获取；

Method myUserId = UserHandle.class.getDeclaredMethod("myUserId");
int userID = (Integer) myUserId.invoke(mPackageManager,null);

获取了以后就可以使用新的getPackageSizeInfo函数了。

getPackageSizeInfoMethod.invoke(mPackageManager,packageInfo.packageName, userID, new MyObserver()
);