線程池+緩存+Handler 異步加載網絡圖片

import java.lang.ref.SoftReference;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.util.Log;
/**

線程池+緩存+Handler加載圖片
*/
public class AsyncLoadImage {
  //緩存
  private Map<String, SoftReference<Drawable>> imageCache = new HashMap<String, SoftReference<Drawable>>();
  //線程池
  private ExecutorService executorService = Executors.newFixedThreadPool(20);//總共有10個線程循環使用
  //Hanlder
  private Handler mHandler = new Handler();
  public interface ImageCallback {

  void imageLoad(Drawable image, String imageUrl);

}
  /*
   

@param imageUrl 圖片的地址
@param imageCallback 回調接口
@return 返回內存中緩存的圖像 第一次返回null
*/
public Drawable loadDrawable(final String imageUrl, final ImageCallback imageCallback) {
 Log.i("AsyncLoadImage", "loadDrawable()" + imageUrl);
 //如果緩存中有則從緩存中取出來
 if(imageCache.containsKey(imageUrl)) {

 SoftReference<Drawable> softReference = imageCache.get(imageUrl);
 if(softReference.get() != null) { //判斷是否有drawable
     return softReference.get(); //有則返回
 }

}
 //使用線程池下載圖片
 executorService.submit(new Runnable() {

 @Override
 public void run() {
     try {
         //                                        final Drawable drawable = Drawable.createFromStream(new URL(imageUrl).openStream(), "image.jpg");
         final Drawable drawable = getDrawableFormUrl(imageUrl); //調用獲取數據的方法
         imageCache.put(imageUrl, new SoftReference<Drawable>(drawable));//將加載的圖片放入到內存中
         mHandler.post(new Runnable() {
             @Override
             public void run() {
                 imageCallback.imageLoad(drawable, imageUrl); //接口回調
             }
         });
     } catch (Exception e) {
         throw new RuntimeException();
     }
 }


});
 return null ;
}
/**

從網絡上獲取數據
*/
public Drawable getDrawableFormUrl(String imageUrl) {
 Drawable drawable = null ;
 try {
 drawable = Drawable.createFromStream(new URL(imageUrl).openStream(), "image.jpg");

 } catch (Exception e) {
 throw new RuntimeException();

 }
 return drawable ;
}



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