Android LruCache用于Bitmap

package com.stone.util;

import android.graphics.Bitmap;
import android.support.v4.util.LruCache;

/**
* author : stone
* email  : aa86799@163.com
* time   : 15/7/23 11 27
*/
public class LruCacheUtil {

private final long MAX_MEMORY = Runtime.getRuntime().maxMemory(); //以字节为单位 byte
private LruCache<String, Bitmap> mLruCache;

public LruCacheUtil() {
mLruCache = new LruCache<String, Bitmap>((int) (MAX_MEMORY / 8)) {//1/8 作缓存区

@Override //必须重写 计算图片占用的内存大小 单位需要与 构造方法参数单位一致
protected int sizeOf(String key, Bitmap value) {
//三种计算size方法
System.out.println(value.getByteCount() + "...");
System.out.println(value.getRowBytes() * value.getHeight() + "...");
System.out.println(value.getWidth() * value.getHeight() * getBytesForConfig(value
.getConfig()) + "...");

return value.getByteCount();
}
};
}

private int getBytesForConfig(Bitmap.Config config) {
switch (config) {
case ALPHA_8:
System.out.println("...ALPHA_8...");
return 1;
case ARGB_4444:
case RGB_565:
System.out.println("...4444-565...");
return 2;
case ARGB_8888:
System.out.println("...8888...");
return 4;
}
return 0;
}

public synchronized void addBitmapToMemoryCache(String key, Bitmap bitmap) {
if (mLruCache.get(key) == null) {
if (key != null && bitmap != null)
mLruCache.put(key, bitmap);
} else
//            Log.w("LruCache", "the res is already exists");
;
}

public synchronized Bitmap getBitmapFromLruCache(String key) {
return mLruCache.get(key);
}

public synchronized void removeImageCache(String key) {
if (key != null) {
Bitmap bm = mLruCache.remove(key);
if (bm != null)
bm.recycle();
}
}

public void clearCache() {
if (mLruCache.size() > 0) {
mLruCache.evictAll(); // mLruCache.trimToSize(-1);
}
}

}

Bitmap bitmap = Bitmap.createBitmap(100, 100, Bitmap.Config.ALPHA_8);
new LruCacheUtil().addBitmapToMemoryCache("abc",  bitmap);