/** * 清除本應用所有數據庫(/data/data/com.xxx.xxx/databases) * * @param context */ 
public static void cleanDatabases(Context context) { 
  deleteFilesByDirectory(new File("/data/data/" 
      + context.getPackageName() + "/databases")); 
} 

/** 
 * * 清除本應用SharedPreference(/data/data/com.xxx.xxx/shared_prefs) * * @param 
 * context 
 */ 
public static void cleanSharedPreference(Context context) { 
  deleteFilesByDirectory(new File("/data/data/" 
      + context.getPackageName() + "/shared_prefs")); 
} 

/** * 清除/data/data/com.xxx.xxx/files下的內容 * * @param context */ 
public static void cleanFiles(Context context) { 
  File sdDir = Environment.getExternalStorageDirectory();//獲取跟目錄 
  sdDir = new File(sdDir.getPath()+File.separator+"xxx"); 
 
  sdDir = new File(sdDir.getPath() +File.separator+ "files"); 
 
  deleteFilesByDirectory(sdDir); 
} 

/** 
 * * 清除外部cache下的內容(/mnt/sdcard/android/data/com.xxx.xxx/cache) * * @param 
 * context 
 */ 
public static void cleanExternalCache(Context context) { 
  if (Environment.getExternalStorageState().equals( 
      Environment.MEDIA_MOUNTED)) { 
    deleteFilesByDirectory(context.getExternalCacheDir()); 
  } 
} 
最后怎么獲取這些數據的大小呢？貼上源碼：
/** 
   * 獲取文件夾大小 
   * @param file File實例 
   * @return long 
   */ 
  public static long getFolderSize(java.io.File file){ 
 
    long size = 0; 
    try { 
      java.io.File[] fileList = file.listFiles(); 
      for (int i = 0; i < fileList.length; i++) 
      { 
          if (fileList[i].isDirectory()) 
          { 
            size = size + getFolderSize(fileList[i]); 
 
          }else{ 
            size = size + fileList[i].length(); 
 
          } 
        } 
 
      } 
    } catch (Exception e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } 
    //return size/1048576; 
    return size; 
  }