优化的Bitmap缓存类

package Utils; import java.lang.ref.SoftReference; import java.util.ArrayList; import java.util.HashMap; import java.util.LinkedList; import java.util.List; import android.graphics.Bitmap; /**  * 优化的bitmap缓存，自动管理缓存，可以设置缓存大小，大于缓存的内容将被移入 轻量级缓存。  *   * @author [email protected]  *   */ public class BitmapCache {  /**   * 缓存大小   */  private static int BUFFER_SIZE = 30;  private static BitmapCache cache;  private HashMap<String, SoftReference<Bitmap>> mImageSoftCache;  private HashMap<String, Bitmap> mImageCache;  private List<String> mKeySet;  public static int getBUFFER_SIZE() {   return BUFFER_SIZE;  }    /**   * 设置缓存大小，超过这个大小的的将被移入softCache.默认大小为25   * @param bUFFER_SIZE   */  public static void setBUFFER_SIZE(int bUFFER_SIZE) {   BUFFER_SIZE = bUFFER_SIZE;  }    private BitmapCache() {   mImageSoftCache = new HashMap<String, SoftReference<Bitmap>>();   mImageCache = new HashMap<String, Bitmap>();   mKeySet = new LinkedList<String>();  }  public static BitmapCache getInstance() {   if (cache == null) {    cache = new BitmapCache();   }   return cache;  }  /***   * @param key   *            image name   * @return   */  public Bitmap getBitmap(String key) {   if (mImageCache.containsKey(key)) {    return mImageCache.get(key);   } else if(mImageSoftCache.containsKey(key)){    if (mKeySet.size() < BUFFER_SIZE) {     return null;    } else{    SoftReference<Bitmap> reference = mImageSoftCache.get(key);    Bitmap bitmap = reference.get();    if (bitmap != null)     return bitmap;    }   }   return null;  }  /**   * 添加到缓存   *    * @param key   * @param bm   */  public void put(String key, Bitmap bm) {   if (mKeySet.size() <= BUFFER_SIZE) {    mImageCache.put(key, bm);    mKeySet.add(key);   } else {    mKeySet.add(key);    final String softKey = mKeySet.remove(0);    final Bitmap softBitmap = mImageCache.remove(softKey);    putSoftReference(softKey, softBitmap);   }  }  /***   *    * @param bitmap   * @param key   */  public void putSoftReference(String key, Bitmap bitmap) {   mImageSoftCache.put(key, new SoftReference<Bitmap>(bitmap));  }    /**   * 回收缓存类,便于重用。   */  public void recycle(){   mImageCache.clear();   mImageSoftCache.clear();   mKeySet.clear();  } }