转载

Android -- DiskLruCache

DiskLruCache

创建一个磁盘缓存对象：

public static DiskLruCache open(File directory, int appVersion, int valueCount, long maxSize)；

open()方法接收四个参数，第一个参数是数据的缓存文件地址，第二个参数是当前应用程序的版本号，第三个参数是同一个key可以对应多少个缓存文件，一般都是传1，第四个参数是最多可以缓存多少字节的数据。

//创建磁盘缓存文件，首选sdcard，如果sdcard没有挂载或者没有sdcard则获取应用默认的cache目录 public static File getDiskCacheDir(Context context, String uniqueName) {  // Check if media is mounted or storage is built-in, if so, try and use external cache dir  // otherwise use internal cache dir  final String cachePath =    Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) ||      !isExternalStorageRemovable() ? getExternalCacheDir(context).getPath() :        context.getCacheDir().getPath();  return new File(cachePath + File.separator + uniqueName); }

获取软件版本号

public int getAppVersion(Context context) {   try {    PackageInfo packageInfo = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);    return packageInfo.versionCode;   } catch (NameNotFoundException e) {    e.printStackTrace();   }   return 1;  }

Java  DiskLruCache mDiskLruCache = null; try {  File cacheDir = getDiskCacheDir(context, "thumbnails");  if (!cacheDir.exists()) {   cacheDir.mkdirs();  }  mDiskLruCache = DiskLruCache.open(cacheDir, getAppVersion(context), 1, 10 * 1024 * 1024); } catch (IOException e) {  e.printStackTrace(); }

磁盘缓存

//添加缓存 public void addBitmapToCache(String key, Bitmap bitmap) {  // Add to memory cache as before，把缓存放到内存缓存中  if (getBitmapFromMemCache(key) == null) {   mMemoryCache.put(key, bitmap);  }  // Also add to disk cache，把缓存放入磁盘缓存  synchronized (mDiskCacheLock) {   if (mDiskLruCache != null && mDiskLruCache.get(key) == null) {    mDiskLruCache.put(key, bitmap);   }  } } //获取缓存 public Bitmap getBitmapFromDiskCache(String key) {  synchronized (mDiskCacheLock) {   // Wait while disk cache is started from background thread   while (mDiskCacheStarting) {    try {     mDiskCacheLock.wait();    } catch (InterruptedException e) {}   }   if (mDiskLruCache != null) {    return mDiskLruCache.get(key);   }  }  return null; }