1/* 2 * Copyright (C) 2012 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 17package com.android.mms.util; 18 19import java.io.IOException; 20import java.nio.ByteBuffer; 21 22import android.content.Context; 23 24public class ImageCacheService { 25 public static final String IMAGE_CACHE_FILE = "imgcache"; 26 private static final int IMAGE_CACHE_MAX_ENTRIES = 500; 27 private static final int IMAGE_CACHE_MAX_BYTES = 20 * 1024 * 1024; 28 private static final int IMAGE_CACHE_VERSION = 3; 29 30 private BlobCache mCache; 31 32 private static long[] sCrcTable = new long[256]; 33 private static final long POLY64REV = 0x95AC9329AC4BC9B5L; 34 private static final long INITIALCRC = 0xFFFFFFFFFFFFFFFFL; 35 36 private Context mContext; 37 38 public ImageCacheService(Context context) { 39 mCache = CacheManager.getCache(context, IMAGE_CACHE_FILE, 40 IMAGE_CACHE_MAX_ENTRIES, IMAGE_CACHE_MAX_BYTES, 41 IMAGE_CACHE_VERSION); 42 mContext = context; 43 } 44 45 public static class ImageData { 46 public ImageData(byte[] data, int offset) { 47 mData = data; 48 mOffset = offset; 49 } 50 public byte[] mData; 51 public int mOffset; 52 } 53 54 public ImageData getImageData(String path, int type) { 55 byte[] key = makeKey(path, type); 56 long cacheKey = crc64Long(key); 57 try { 58 byte[] value = null; 59 synchronized (mCache) { 60 value = mCache.lookup(cacheKey); 61 } 62 if (value == null) return null; 63 if (isSameKey(key, value)) { 64 int offset = key.length; 65 return new ImageData(value, offset); 66 } 67 } catch (IOException ex) { 68 // ignore. 69 } 70 return null; 71 } 72 73 public void putImageData(String path, int type, byte[] value) { 74 byte[] key = makeKey(path, type); 75 long cacheKey = crc64Long(key); 76 ByteBuffer buffer = ByteBuffer.allocate(key.length + value.length); 77 buffer.put(key); 78 buffer.put(value); 79 synchronized (mCache) { 80 try { 81 mCache.insert(cacheKey, buffer.array()); 82 } catch (IOException ex) { 83 // ignore. 84 } 85 } 86 } 87 88 public void clear() { 89 CacheManager.clear(mContext); 90 } 91 92 private static byte[] makeKey(String path, int type) { 93 return getBytes(path + "+" + type); 94 } 95 96 private static boolean isSameKey(byte[] key, byte[] buffer) { 97 int n = key.length; 98 if (buffer.length < n) { 99 return false; 100 } 101 for (int i = 0; i < n; ++i) { 102 if (key[i] != buffer[i]) { 103 return false; 104 } 105 } 106 return true; 107 } 108 109 /** 110 * A function thats returns a 64-bit crc for string 111 * 112 * @param in input string 113 * @return a 64-bit crc value 114 */ 115 public static final long crc64Long(String in) { 116 if (in == null || in.length() == 0) { 117 return 0; 118 } 119 return crc64Long(getBytes(in)); 120 } 121 122 static { 123 // http://bioinf.cs.ucl.ac.uk/downloads/crc64/crc64.c 124 long part; 125 for (int i = 0; i < 256; i++) { 126 part = i; 127 for (int j = 0; j < 8; j++) { 128 long x = ((int) part & 1) != 0 ? POLY64REV : 0; 129 part = (part >> 1) ^ x; 130 } 131 sCrcTable[i] = part; 132 } 133 } 134 135 public static final long crc64Long(byte[] buffer) { 136 long crc = INITIALCRC; 137 for (int k = 0, n = buffer.length; k < n; ++k) { 138 crc = sCrcTable[(((int) crc) ^ buffer[k]) & 0xff] ^ (crc >> 8); 139 } 140 return crc; 141 } 142 143 public static byte[] getBytes(String in) { 144 byte[] result = new byte[in.length() * 2]; 145 int output = 0; 146 for (char ch : in.toCharArray()) { 147 result[output++] = (byte) (ch & 0xFF); 148 result[output++] = (byte) (ch >> 8); 149 } 150 return result; 151 } 152 153} 154