대상을 향한 6대 원칙 중 하나

단일 직책 원칙(코드 최적화의 첫걸음)

public class ImageLoader {

//    
public LruCache bitmapLruCache;

//         cup  
ExecutorService executorService =       
Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
public ImageLoader() {
    initCache();
}

/***
 *     
 */
public void initCache() {
    int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
    int cacheSize = maxMemory / 4; //      
    bitmapLruCache = new LruCache(cacheSize) {
        @Override
        protected int sizeOf(String key, Bitmap value) {
            return value.getRowBytes() * value.getHeight() / 1024;    
            //         
        }
    };
}

/**
 *     
 *
 * @param url
 * @param imageView
 */
public void displayImage(final String url, final ImageView imageView) {
    imageView.setTag(url);
    executorService.submit(new Runnable() {
        @Override
        public void run() {
            Bitmap bitmap = downloadImage(url);
            imageView.setImageBitmap(bitmap);
            //  
            bitmapLruCache.put(url, bitmap);
        }
    });
}

/**
 *       
 *
 * @param url
 */
private Bitmap downloadImage(String url) {
    Bitmap bitmap = null;

    try {
        URL url1 = new URL(url);
        HttpURLConnection httpURLConnection = (HttpURLConnection)   
        url1.openConnection();
        bitmap = BitmapFactory.decodeStream(httpURLConnection.getInputStream());
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return bitmap;
  }
}

![    UML ](http://note.youdao.com/favicon.ico) 



 public class ImageCache {
    //    
    public LruCache bitmapLruCache;
    //         cup  
    ExecutorService executorService =     
    Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());

    public static ImageCache imageCache;

   public static ImageCache getInstache() {
         if (imageCache == null) {
         imageCache = new ImageCache();
         }
        return imageCache;
     }

    public ImageCache() {
       initCache();
    }


/**    */ 

public void initCache() {
int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
int cacheSize = maxMemory / 4; //      
 bitmapLruCache = new LruCache(cacheSize) {
 @Override
 protected int sizeOf(String key, Bitmap value) {
 return value.getRowBytes() * value.getHeight() / 1024; //         
    }
  };
 }
 public void put(String url, Bitmap bitmap) {
   bitmapLruCache.put(url, bitmap);
 }

 public Bitmap getBitmap(String url) {
   if (bitmapLruCache != null) {
     return bitmapLruCache.get(url);
    }
  return null;
 }

}