/**
 * 个人觉得没必要用map来缓存实例，一个就够用了
 * @param cacheDir
 * @param max_zise
 * @param max_count
 * @return
 */
public  static ACache get(File cacheDir, long max_zise, int max_count) {
    if (instance == null) {
        synchronized (ACache.class) {
            //ACache manager = mInstanceMap.get(cacheDir.getAbsoluteFile() + myPid());
            if (instance == null) {
                instance = new ACache(cacheDir, max_zise, max_count);
                //mInstanceMap.put(cacheDir.getAbsolutePath() + myPid(), manager);
            }
        }
    }
    return instance;
}

    /**
     * hashCode发生碰撞怎么办，我建议用base64
     * @param key
     * @return
     */
    private File newFile(String key) {
        //return new File(cacheDir, key.hashCode() + "");
        return new File(cacheDir, Base64.encodeToString(key.getBytes(), Base64.NO_WRAP) + "");
    }

package com.sunkun.cache;

import java.io.File;

import javax.management.ImmutableDescriptor;

public class SimpleCacheTest {
    public static void main(String args[])
    {
        SimpleCache mCache = SimpleCache.get(new File("").getAbsoluteFile(),10l,1000);

        ImmutableDescriptor object = new ImmutableDescriptor("name=sunkun");

        mCache.put("TestObject",object,1);
        //测试超时
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        if(!mCache.getAsObject("TestObject").equals(object))
            System.out.println("failed");
        else
            System.out.println("suceed");

    }
}

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);
        }

        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);
                }
        }

 File mFile = new File("test.txt");

 ACache mCache = ACache.get(this);
 mCache.put("myFileKey", mFile);

 FileOutputStream out = new FileOutputStream(mFile);
 out.write("my bytes".getBytes());