1 // Copyright 2011 Google Inc. All Rights Reserved.
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
7 // http://www.apache.org/licenses/LICENSE-2.0
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
15 package com.hughes.android.util;
18 import java.io.FileInputStream;
19 import java.io.FileOutputStream;
20 import java.io.ObjectInputStream;
21 import java.io.ObjectOutputStream;
22 import java.util.LinkedHashMap;
25 import android.content.Context;
26 import android.util.Log;
28 public class PersistentObjectCache {
30 private final File dir;
31 private final Map<String, Object> objects = new LinkedHashMap<String, Object>();
33 public synchronized <T> T read(final String filename, final Class<T> resultClass) {
35 Object object = (objects.get(filename));
37 return resultClass.cast(object);
39 Log.d(getClass().getSimpleName(), "Cache miss.");
40 final File src = new File(dir, filename);
42 Log.d(getClass().getSimpleName(), "File empty: " + src);
46 final ObjectInputStream in = new ObjectInputStream(new FileInputStream(src));
47 object = in.readObject();
49 } catch (Exception e) {
50 Log.e(getClass().getSimpleName(), "Deserialization failed: " + src, e);
53 objects.put(filename, object);
54 return resultClass.cast(object);
55 } catch (ClassCastException e) {
60 public synchronized void write(final String filename, final Object object) {
61 objects.put(filename, object);
62 final File dest = new File(dir, filename);
64 final ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(dest));
65 out.writeObject(object);
67 } catch (Exception e) {
68 Log.e(getClass().getSimpleName(), "Serialization failed: " + dest, e);
72 private PersistentObjectCache(final Context context) {
73 dir = context.getFilesDir();
75 throw new RuntimeException("context.getFilesDir() == null");
79 public static synchronized PersistentObjectCache getInstance() {
80 if (instance == null) {
81 throw new RuntimeException("getInstance called before init.");
86 public static synchronized PersistentObjectCache init(final Context context) {
87 if (instance == null) {
88 instance = new PersistentObjectCache(context);
90 if (!instance.dir.equals(context.getFilesDir())) {
91 throw new RuntimeException("File dir changed. old=" + instance.dir + ", new=" + context.getFilesDir());
97 private static PersistentObjectCache instance = null;