Android应用List图标异步加载

		

	 

	1、创建异步加载类：

	 

	 

	 

	 

	 

	Java代码 

	import android.graphics.drawable.Drawable;  

	import android.os.Handler;  

	import android.os.Message;  

	import android.widget.ImageView;  

	 

	import java.io.IOException;  

	import java.io.InputStream;  

	import java.lang.ref.SoftReference;  

	import java.net.MalformedURLException;  

	import java.net.URL;  

	import java.util.HashMap;  

	 

	public class AsyncImageLoader {  

	    // SoftReference是软引用，是为了更好的为了系统回收变量  

	    private HashMap<String, SoftReference<Drawable>> imageCache;  

	 

	    public AsyncImageLoader() {  

	        imageCache = new HashMap<String, SoftReference<Drawable>>();  

	    }  

	 

	    public Drawable loadDrawable(final String imageUrl, final ImageView imageView,  

	            final ImageCallback imageCallback) {  

	        if (imageCache.containsKey(imageUrl)) {  

	            // 从缓存中获取  

	            SoftReference<Drawable> softReference = imageCache.get(imageUrl);  

	            Drawable drawable = softReference.get();  

	            if (drawable != null) {  

	                return drawable;  

	            }  

	        }  

	        final Handler handler = new Handler() {  

	            public void handleMessage(Message message) {  

	                imageCallback.imageLoaded((Drawable) message.obj, imageView, imageUrl);  

	            }  

	        };  

	        // 建立新一个新的线程下载图片  

	        new Thread() {  

	            @Override 

	            public void run() {  

	                Drawable drawable = loadImageFromUrl(imageUrl);  

	                imageCache.put(imageUrl, new SoftReference<Drawable>(drawable));  

	                Message message = handler.obtainMessage(0, drawable);  

	                handler.sendMessage(message);  

	            }  

	        }.start();  

	        return null;  

	    }  

	 

	    public static Drawable loadImageFromUrl(String url) {  

	        URL m;  

	        InputStream i = null;  

	        try {  

	            m = new URL(url);  

	            i = (InputStream) m.getContent();  

	        } catch (MalformedURLException e1) {  

	            e1.printStackTrace();  

	        } catch (IOException e) {  

	            e.printStackTrace();  

	        }  

	        Drawable d = Drawable.createFromStream(i, "src");  

	        return d;  

	    }  

	 

	    // 回调接口  

	    public interface ImageCallback {  

	        public void imageLoaded(Drawable imageDrawable, ImageView imageView, String imageUrl);  

	    }  

	} 

	 

	import android.graphics.drawable.Drawable;

	import android.os.Handler;

	import android.os.Message;

	import android.widget.ImageView;

	 

	import java.io.IOException;

	import java.io.InputStream;

	import java.lang.ref.SoftReference;

	import java.net.MalformedURLException;

	import java.net.URL;

	import java.util.HashMap;

	 

	public class AsyncImageLoader {

	    // SoftReference是软引用，是为了更好的为了系统回收变量

	    private HashMap<String, SoftReference<Drawable>> imageCache;

	 

	    public AsyncImageLoader() {

	        imageCache = new HashMap<String, SoftReference<Drawable>>();

	    }

	 

	    public Drawable loadDrawable(final String imageUrl, final ImageView imageView,

	            final ImageCallback imageCallback) {

	        if (imageCache.containsKey(imageUrl)) {

	            // 从缓存中获取

	            SoftReference<Drawable> softReference = imageCache.get(imageUrl);

	            Drawable drawable = softReference.get();

	            if (drawable != null) {

	                return drawable;

	            }

	        }

	        final Handler handler = new Handler() {

	            public

补充：移动开发 , Android ,

上一个：给Android应用开发者的十个建议
下一个：开发者必知：提升Android应用开发性能的十大要点