1 /*
2  * Copyright (C) 2010 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.gallery3d.util;
18 
19 import android.content.Context;
20 import android.content.SharedPreferences;
21 import android.preference.PreferenceManager;
22 
23 import com.android.gallery3d.common.BlobCache;
24 
25 import java.io.File;
26 import java.io.IOException;
27 import java.util.HashMap;
28 
29 public class CacheManager {
30     private static final String TAG = "CacheManager";
31     private static final String KEY_CACHE_UP_TO_DATE = "cache-up-to-date";
32     private static HashMap<String, BlobCache> sCacheMap =
33             new HashMap<String, BlobCache>();
34     private static boolean sOldCheckDone = false;
35 
36     // Return null when we cannot instantiate a BlobCache, e.g.:
37     // there is no SD card found.
38     // This can only be called from data thread.
getCache(Context context, String filename, int maxEntries, int maxBytes, int version)39     public static BlobCache getCache(Context context, String filename,
40             int maxEntries, int maxBytes, int version) {
41         synchronized (sCacheMap) {
42             if (!sOldCheckDone) {
43                 removeOldFilesIfNecessary(context);
44                 sOldCheckDone = true;
45             }
46             BlobCache cache = sCacheMap.get(filename);
47             if (cache == null) {
48                 File cacheDir = context.getExternalCacheDir();
49                 String path = cacheDir.getAbsolutePath() + "/" + filename;
50                 try {
51                     cache = new BlobCache(path, maxEntries, maxBytes, false,
52                             version);
53                     sCacheMap.put(filename, cache);
54                 } catch (IOException e) {
55                     Log.e(TAG, "Cannot instantiate cache!", e);
56                 }
57             }
58             return cache;
59         }
60     }
61 
62     // Removes the old files if the data is wiped.
removeOldFilesIfNecessary(Context context)63     private static void removeOldFilesIfNecessary(Context context) {
64         SharedPreferences pref = PreferenceManager
65                 .getDefaultSharedPreferences(context);
66         int n = 0;
67         try {
68             n = pref.getInt(KEY_CACHE_UP_TO_DATE, 0);
69         } catch (Throwable t) {
70             // ignore.
71         }
72         if (n != 0) return;
73         pref.edit().putInt(KEY_CACHE_UP_TO_DATE, 1).commit();
74 
75         File cacheDir = context.getExternalCacheDir();
76         String prefix = cacheDir.getAbsolutePath() + "/";
77 
78         BlobCache.deleteFiles(prefix + "imgcache");
79         BlobCache.deleteFiles(prefix + "rev_geocoding");
80         BlobCache.deleteFiles(prefix + "bookmark");
81     }
82 }
83