Android Memory optimized memory cache

Objective:

The memory cache is described in the previous article, and the advantage of memory caching is that it is fast, but it has drawbacks:

• Small space, memory cache can not be very large;
• may be cleared when memory is tight;
• When the application exits, it disappears and does not go offline;

Based on the disadvantages above, sometimes another kind of cache is needed, that is, the disk cache. Everyone should have used the news client, many have offline functions, the implementation of the function is the disk cache.

Disklrucache:

Most of the disk caches used in Android are based on the Disklrucache implementation, how to use them?

• Create a disk Cache object:

public static Disklrucache open (File directory, int appversion, int valuecount, long maxSize);

The Open () method receives four parameters, the first parameter is the cached file address of the data, the second parameter is the version number of the current application, the third parameter is the same key can correspond to how many cache files, generally is 1, the fourth parameter is the maximum number of bytes of data can be cached, 10M?

• To get the cache path:

Creates a unique subdirectory of the designated app cache directory. Tries to using external//but if not mounted, falls back on internal storage.//Create disk cache file, preferred sdcard, if sdcard is not mounted or not SDcard get app Default cache directory public static File Getdiskcachedir (context context, String UniqueName) {    //Check If media is mounted or sto  Rage 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);}

• Get software version number:

public int Getappversion (context context) {try {packageinfo packageinfo = Context.getpackagemanager (). Getpackageinfo ( Context.getpackagename (), 0); return packageinfo.versioncode;} catch (Namenotfoundexception e) {e.printstacktrace ();} return 1;}

• The complete code is as follows:

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 ();}

• Specifically how to use the disk cache created above is as follows:

Add cache public void Addbitmaptocache (String key, Bitmap Bitmap) {    //Add to memory cache as before, put the cache in the    Tbitmapfrommemcache (key) = = null) {        mmemorycache.put (key, bitmap);    }    Also add to disk cache, put the cache into the disk buffer    synchronized (mdiskcachelock) {        if (mdisklrucache! = null && Mdisklruc Ache.get (key) = = null) {            mdisklrucache.put (key, bitmap);}}}    Get Cache public Bitmap Getbitmapfromdiskcache (String key) {    synchronized (mdiskcachelock) {        //Wait while disk Cache is started from background the thread        while (mdiskcachestarting) {            try {                mdiskcachelock.wait ();            } catch (Interruptedexception e) {}        }        if (Mdisklrucache! = null) {            return mdisklrucache.get (key);        }    }    return null;}

Summarize:

The above is how the disk cache is created and used. In practice, the memory cache and the disk cache are used together, typically reading data from the in-memory cache, if no more is read from the disk cache. Personal level is limited, what questions can leave a message, the best is to add my public number:coder_online, I can timely see your message and give you an answer.

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Android Memory optimized memory cache