ACache是一个为android制定的 轻量级的 开源缓存框架。轻量到只有一个java文件（由十几个类精简而来）。
1、它可以缓存什么东西？
普通的字符串、json、序列化的java对象，和 字节数字。
2、它有什么特色？
特色主要是：
1：轻，轻到只有一个JAVA文件。
2：可配置，可以配置缓存路径，缓存大小，缓存数量等。
3：可以设置缓存超时时间，缓存超时自动失效，并被删除。
4：多进程的支持。
下面附上完整代码：
public class ACache { public static final int TIME_HOUR = 60 * 60; public static final int TIME_DAY = TIME_HOUR * 24; private static final int MAX_SIZE = 1000 * 1000 * 50; // 50 mb private static final int MAX_COUNT = Integer.MAX_VALUE; // 不限制存放数据的数量 private static Map<String, ACache> mInstanceMap = new HashMap<String, ACache>(); private ACacheManager mCache; public static ACache get(Context ctx) { return get(ctx, "ACache"); } public static ACache get(Context ctx, String cacheName) { File f = new File(ctx.getCacheDir(), cacheName); return get(f, MAX_SIZE, MAX_COUNT); } public static ACache get(File cacheDir) { return get(cacheDir, MAX_SIZE, MAX_COUNT); } public static ACache get(Context ctx, long max_zise, int max_count) { File f = new File(ctx.getCacheDir(), "ACache"); return get(f, max_zise, max_count); } public static ACache get(File cacheDir, long max_zise, int max_count) { ACache manager = mInstanceMap.get(cacheDir.getAbsoluteFile() + myPid()); if (manager == null) { manager = new ACache(cacheDir, max_zise, max_count); mInstanceMap.put(cacheDir.getAbsolutePath() + myPid(), manager); } return manager; } private static String myPid() { return "_" + android.os.Process.myPid(); } private ACache(File cacheDir, long max_size, int max_count) { if (!cacheDir.exists() && !cacheDir.mkdirs()) { throw new RuntimeException("can't make dirs in " + cacheDir.getAbsolutePath()); } mCache = new ACacheManager(cacheDir, max_size, max_count); } // ======================================= // ============ String数据 读写 ============== // ======================================= /** * 保存 String数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的String数据 */ public void put(String key, String value) { File file = mCache.newFile(key); BufferedWriter out = null; try { out = new BufferedWriter(new FileWriter(file), 1024); out.write(value); } catch (IOException e) { e.printStackTrace(); } finally { if (out != null) { try { out.flush(); out.close(); } catch (IOException e) { e.printStackTrace(); } } mCache.put(file); } } /** * 保存 String数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的String数据 * @param saveTime * 保存的时间，单位：秒 */ public void put(String key, String value, int saveTime) { put(key, Utils.newStringWithDateInfo(saveTime, value)); } /** * 读取 String数据 * * @param key * @return String 数据 */ public String getAsString(String key) { File file = mCache.get(key); if (!file.exists()) return null; boolean removeFile = false; BufferedReader in = null; try { in = new BufferedReader(new FileReader(file)); String readString = ""; String currentLine; while ((currentLine = in.readLine()) != null) { readString += currentLine; } if (!Utils.isDue(readString)) { return Utils.clearDateInfo(readString); } else { removeFile = true; return null; } } catch (IOException e) { e.printStackTrace(); return null; } finally { if (in != null) { try { in.close(); } catch (IOException e) { e.printStackTrace(); } } if (removeFile) remove(key); } } // ======================================= // ============= JSONObject 数据 读写 ============== // ======================================= /** * 保存 JSONObject数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的JSON数据 */ public void put(String key, JSONObject value) { put(key, value.toString()); } /** * 保存 JSONObject数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的JSONObject数据 * @param saveTime * 保存的时间，单位：秒 */ public void put(String key, JSONObject value, int saveTime) { put(key, value.toString(), saveTime); } /** * 读取JSONObject数据 * * @param key * @return JSONObject数据 */ public JSONObject getAsJSONObject(String key) { String JSONString = getAsString(key); try { JSONObject obj = new JSONObject(JSONString); return obj; } catch (Exception e) { e.printStackTrace(); return null; } } // ======================================= // ============ JSONArray 数据 读写 ============= // ======================================= /** * 保存 JSONArray数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的JSONArray数据 */ public void put(String key, JSONArray value) { put(key, value.toString()); } /** * 保存 JSONArray数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的JSONArray数据 * @param saveTime * 保存的时间，单位：秒 */ public void put(String key, JSONArray value, int saveTime) { put(key, value.toString(), saveTime); } /** * 读取JSONArray数据 * * @param key * @return JSONArray数据 */ public JSONArray getAsJSONArray(String key) { String JSONString = getAsString(key); try { JSONArray obj = new JSONArray(JSONString); return obj; } catch (Exception e) { e.printStackTrace(); return null; } } // ======================================= // ============== byte 数据 读写 ============= // ======================================= /** * 保存 byte数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的数据 */ public void put(String key, byte[] value) { File file = mCache.newFile(key); FileOutputStream out = null; try { out = new FileOutputStream(file); out.write(value); } catch (Exception e) { e.printStackTrace(); } finally { if (out != null) { try { out.flush(); out.close(); } catch (IOException e) { e.printStackTrace(); } } mCache.put(file); } } /** * 保存 byte数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的数据 * @param saveTime * 保存的时间，单位：秒 */ public void put(String key, byte[] value, int saveTime) { put(key, Utils.newByteArrayWithDateInfo(saveTime, value)); } /** * 获取 byte 数据 * * @param key * @return byte 数据 */ public byte[] getAsBinary(String key) { RandomAccessFile RAFile = null; boolean removeFile = false; try { File file = mCache.get(key); if (!file.exists()) return null; RAFile = new RandomAccessFile(file, "r"); byte[] byteArray = new byte[(int) RAFile.length()]; RAFile.read(byteArray); if (!Utils.isDue(byteArray)) { return Utils.clearDateInfo(byteArray); } else { removeFile = true; return null; } } catch (Exception e) { e.printStackTrace(); return null; } finally { if (RAFile != null) { try { RAFile.close(); } catch (IOException e) { e.printStackTrace(); } } if (removeFile) remove(key); } } // ======================================= // ============= 序列化 数据 读写 =============== // ======================================= /** * 保存 Serializable数据 到 缓存中 * * @param key * 保存的key * @param value * 保存的value */ public void put(String key, Serializable value) { put(key, value, -1); } /** * 保存 Serializable数据到 缓存中 * * @param key * 保存的key * @param value * 保存的value * @param saveTime * 保存的时间，单位：秒 */ public void put(String key, Serializable value, int saveTime) { ByteArrayOutputStream baos = null; ObjectOutputStream oos = null; try { baos = new ByteArrayOutputStream(); oos = new ObjectOutputStream(baos); oos.writeObject(value); byte[] data = baos.toByteArray(); if (saveTime != -1) { put(key, data, saveTime); } else { put(key, data); } } catch (Exception e) { e.printStackTrace(); } finally { try { oos.close(); } catch (IOException e) { } } } /** * 读取 Serializable数据 * * @param key * @return Serializable 数据 */ public Object getAsObject(String key) { byte[] data = getAsBinary(key); if (data != null) { ByteArrayInputStream bais = null; ObjectInputStream ois = null; try { bais = new ByteArrayInputStream(data); ois = new ObjectInputStream(bais); Object reObject = ois.readObject(); return reObject; } catch (Exception e) { e.printStackTrace(); return null; } finally { try { if (bais != null) bais.close(); } catch (IOException e) { e.printStackTrace(); } try { if (ois != null) ois.close(); } catch (IOException e) { e.printStackTrace(); } } } return null; } // ======================================= // ============== bitmap 数据 读写 ============= // ======================================= /** * 保存 bitmap 到 缓存中 * * @param key * 保存的key * @param value * 保存的bitmap数据 */ public void put(String key, Bitmap value) { put(key, Utils.Bitmap2Bytes(value)); } /** * 保存 bitmap 到 缓存中 * * @param key * 保存的key * @param value * 保存的 bitmap 数据 * @param saveTime * 保存的时间，单位：秒 */ public void put(String key, Bitmap value, int saveTime) { put(key, Utils.Bitmap2Bytes(value), saveTime); } /** * 读取 bitmap 数据 * * @param key * @return bitmap 数据 */ public Bitmap getAsBitmap(String key) { if (getAsBinary(key) == null) { return null; } return Utils.Bytes2Bimap(getAsBinary(key)); } // ======================================= // ============= drawable 数据 读写 ============= // ======================================= /** * 保存 drawable 到 缓存中 * * @param key * 保存的key * @param value * 保存的drawable数据 */ public void put(String key, Drawable value) { put(key, Utils.drawable2Bitmap(value)); } /** * 保存 drawable 到 缓存中 * * @param key * 保存的key * @param value * 保存的 drawable 数据 * @param saveTime * 保存的时间，单位：秒 */ public void put(String key, Drawable value, int saveTime) { put(key, Utils.drawable2Bitmap(value), saveTime); } /** * 读取 Drawable 数据 * * @param key * @return Drawable 数据 */ public Drawable getAsDrawable(String key) { if (getAsBinary(key) == null) { return null; } return Utils.bitmap2Drawable(Utils.Bytes2Bimap(getAsBinary(key))); } /** * 获取缓存文件 * * @param key * @return value 缓存的文件 */ public File file(String key) { File f = mCache.newFile(key); if (f.exists()) return f; return null; } /** * 移除某个key * * @param key * @return 是否移除成功 */ public boolean remove(String key) { return mCache.remove(key); } /** * 清除所有数据 */ public void clear() { mCache.clear(); } /** * @title 缓存管理器 * @version 1.0 */ public class ACacheManager { private final AtomicLong cacheSize; private final AtomicInteger cacheCount; private final long sizeLimit; private final int countLimit; private final Map<File, Long> lastUsageDates = Collections .synchronizedMap(new HashMap<File, Long>()); protected File cacheDir; private ACacheManager(File cacheDir, long sizeLimit, int countLimit) { this.cacheDir = cacheDir; this.sizeLimit = sizeLimit; this.countLimit = countLimit; cacheSize = new AtomicLong(); cacheCount = new AtomicInteger(); calculateCacheSizeAndCacheCount(); } /** * 计算 cacheSize和cacheCount */ private void calculateCacheSizeAndCacheCount() { new Thread(new Runnable() { @Override public void run() { int size = 0; int count = 0; File[] cachedFiles = cacheDir.listFiles(); if (cachedFiles != null) { for (File cachedFile : cachedFiles) { size += calculateSize(cachedFile); count += 1; lastUsageDates.put(cachedFile, cachedFile.lastModified()); } cacheSize.set(size); cacheCount.set(count); } } }).start(); } private void put(File file) { int curCacheCount = cacheCount.get(); while (curCacheCount + 1 > countLimit) { long freedSize = removeNext(); cacheSize.addAndGet(-freedSize); curCacheCount = cacheCount.addAndGet(-1); } cacheCount.addAndGet(1); long valueSize = calculateSize(file); long curCacheSize = cacheSize.get(); while (curCacheSize + valueSize > sizeLimit) { long freedSize = removeNext(); curCacheSize = cacheSize.addAndGet(-freedSize); } cacheSize.addAndGet(valueSize); Long currentTime = System.currentTimeMillis(); file.setLastModified(currentTime); lastUsageDates.put(file, currentTime); } private File get(String key) { File file = newFile(key); Long currentTime = System.currentTimeMillis(); file.setLastModified(currentTime); lastUsageDates.put(file, currentTime); return file; } private File newFile(String key) { return new File(cacheDir, key.hashCode() + ""); } private boolean remove(String key) { File image = get(key); return image.delete(); } private void clear() { lastUsageDates.clear(); cacheSize.set(0); File[] files = cacheDir.listFiles(); if (files != null) { for (File f : files) { f.delete(); } } } /** * 移除旧的文件 * * @return */ private long removeNext() { if (lastUsageDates.isEmpty()) { return 0; } Long oldestUsage = null; File mostLongUsedFile = null; Set<Entry<File, Long>> entries = lastUsageDates.entrySet(); synchronized (lastUsageDates) { for (Entry<File, Long> entry : entries) { if (mostLongUsedFile == null) { mostLongUsedFile = entry.getKey(); oldestUsage = entry.getValue(); } else { Long lastValueUsage = entry.getValue(); if (lastValueUsage < oldestUsage) { oldestUsage = lastValueUsage; mostLongUsedFile = entry.getKey(); } } } } long fileSize = calculateSize(mostLongUsedFile); if (mostLongUsedFile.delete()) { lastUsageDates.remove(mostLongUsedFile); } return fileSize; } private long calculateSize(File file) { return file.length(); } } /** * @title 时间计算工具类 * @version 1.0 */ private static class Utils { /** * 判断缓存的String数据是否到期 * * @param str * @return true：到期了 false：还没有到期 */ private static boolean isDue(String str) { return isDue(str.getBytes()); } /** * 判断缓存的byte数据是否到期 * * @param data * @return true：到期了 false：还没有到期 */ private static boolean isDue(byte[] data) { String[] strs = getDateInfoFromDate(data); if (strs != null && strs.length == 2) { String saveTimeStr = strs[0]; while (saveTimeStr.startsWith("0")) { saveTimeStr = saveTimeStr .substring(1, saveTimeStr.length()); } long saveTime = Long.valueOf(saveTimeStr); long deleteAfter = Long.valueOf(strs[1]); if (System.currentTimeMillis() > saveTime + deleteAfter * 1000) { return true; } } return false; } private static String newStringWithDateInfo(int second, String strInfo) { return createDateInfo(second) + strInfo; } private static byte[] newByteArrayWithDateInfo(int second, byte[] data2) { byte[] data1 = createDateInfo(second).getBytes(); byte[] retdata = new byte[data1.length + data2.length]; System.arraycopy(data1, 0, retdata, 0, data1.length); System.arraycopy(data2, 0, retdata, data1.length, data2.length); return retdata; } private static String clearDateInfo(String strInfo) { if (strInfo != null && hasDateInfo(strInfo.getBytes())) { strInfo = strInfo.substring(strInfo.indexOf(mSeparator) + 1, strInfo.length()); } return strInfo; } private static byte[] clearDateInfo(byte[] data) { if (hasDateInfo(data)) { return copyOfRange(data, indexOf(data, mSeparator) + 1, data.length); } return data; } private static boolean hasDateInfo(byte[] data) { return data != null && data.length > 15 && data[13] == '-' && indexOf(data, mSeparator) > 14; } private static String[] getDateInfoFromDate(byte[] data) { if (hasDateInfo(data)) { String saveDate = new String(copyOfRange(data, 0, 13)); String deleteAfter = new String(copyOfRange(data, 14, indexOf(data, mSeparator))); return new String[] { saveDate, deleteAfter }; } return null; } private static int indexOf(byte[] data, char c) { for (int i = 0; i < data.length; i++) { if (data[i] == c) { return i; } } return -1; } private static byte[] copyOfRange(byte[] original, int from, int to) { int newLength = to - from; if (newLength < 0) throw new IllegalArgumentException(from + " > " + to); byte[] copy = new byte[newLength]; System.arraycopy(original, from, copy, 0, Math.min(original.length - from, newLength)); return copy; } private static final char mSeparator = ' '; private static String createDateInfo(int second) { String currentTime = System.currentTimeMillis() + ""; while (currentTime.length() < 13) { currentTime = "0" + currentTime; } return currentTime + "-" + second + mSeparator; } /* * Bitmap → byte[] */ private static byte[] Bitmap2Bytes(Bitmap bm) { if (bm == null) { return null; } ByteArrayOutputStream baos = new ByteArrayOutputStream(); bm.compress(Bitmap.CompressFormat.PNG, 100, baos); return baos.toByteArray(); } /* * byte[] → Bitmap */ private static Bitmap Bytes2Bimap(byte[] b) { if (b.length == 0) { return null; } return BitmapFactory.decodeByteArray(b, 0, b.length); } /* * Drawable → Bitmap */ private static Bitmap drawable2Bitmap(Drawable drawable) { if (drawable == null) { return null; } // 取 drawable 的长宽 int w = drawable.getIntrinsicWidth(); int h = drawable.getIntrinsicHeight(); // 取 drawable 的颜色格式 Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565; // 建立对应 bitmap Bitmap bitmap = Bitmap.createBitmap(w, h, config); // 建立对应 bitmap 的画布 Canvas canvas = new Canvas(bitmap); drawable.setBounds(0, 0, w, h); // 把 drawable 内容画到画布中 drawable.draw(canvas); return bitmap; } /* * Bitmap → Drawable */ @SuppressWarnings("deprecation") private static Drawable bitmap2Drawable(Bitmap bm) { if (bm == null) { return null; } return new BitmapDrawable(bm); } }}这个工具类，感觉很好，拿出来分享下。