How to delete cache-folder of app?

问题:

I read through the Android documentation of the cache (see Data Storage Documentation) but I didn't got how I can clean the whole folder.

So how can I delete the cache-folder of my app? It's in this path:

/Android/data/de.stepforward/cache/

回答1:

Put this code in onDestroy() to clear app cache:

void onDestroy() { super.onDestroy();

    try {
        trimCache(this);
       // Toast.makeText(this,"onDestroy " ,Toast.LENGTH_LONG).show();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}

public static void trimCache(Context context) {
    try {
       File dir = context.getCacheDir();
       if (dir != null && dir.isDirectory()) {
          deleteDir(dir);
       }
    } catch (Exception e) {
       // TODO: handle exception
    }
 }

 public static boolean deleteDir(File dir) {
    if (dir != null && dir.isDirectory()) {
       String[] children = dir.list();
       for (int i = 0; i < children.length; i++) {
          boolean success = deleteDir(new File(dir, children[i]));
          if (!success) {
             return false;
          }
       }
    }

    // The directory is now empty so delete it
    return dir.delete();
 }

回答2:

You can use the code referenced here:

https://stackoverflow.com/a/7600257/327011

File cacheDir = context.getCacheDir();

File[] files = cacheDir.listFiles();

if (files != null) {
    for (File file : files)
       file.delete();
}

回答3:

Rather than rolling your own utility methods, you may want to consider using the apache commons FileUtils library. It contains a lot of useful File manipulation methods and makes operations like this very trivial.

Here are the JavaDocs

And here is an example:

try {
    FileUtils.deleteDirectory(context.getCacheDir());
} catch (IOException e) {
    Log.e(LOGTAG,"Error deleting cache dir", e);
}

Alternately, rather than deleting the whole cache directory, you may want to create subdirectories within the app's cache directory for specific data. Than you can delete those specific directories when required (e.g. on user logout).

回答4:

From the documentation:

Saving cache files

If you'd like to cache some data, rather than store it persistently, you should use getCacheDir() to open a File that represents the internal directory where your application should save temporary cache files.

When the device is low on internal storage space, Android may delete these cache files to recover space. However, you should not rely on the system to clean up these files for you. You should always maintain the cache files yourself and stay within a reasonable limit of space consumed, such as 1MB. When the user uninstalls your application, these files are removed.

Create a method to recurse through the folder and delete them, if that's what you want to do.