android中异步加载图片.doc

package com.down;import java.io.IOException;import java.io.InputStream;import java.lang.ref.SoftReference;import .MalformedURLException;import .URL;import java.util.HashMap;import android.app.Activity;import android.graphics.drawable.Drawable;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.ImageView;/import com.down.AsyncImageLoader.ImageCallback;/异步加载public class LazyLoadImageActivity extends Activity AsyncImageLoader asyncImageLoader;String imageUrl;Callbackimg callback;Drawable drawable;android.widget.ImageView imageView1;android.widget.ImageView imageView2;android.widget.ImageView imageView3;AsyncImageLoader loder;String path = 6:8080/downPicService/DownPicServlet;String imgpath;String str;HashMapString, SoftReference hashmap;public void onCreate(Bundle savedInstanceState) super.onCreate(savedInstanceState);setContentView(R.layout.main);hashmap = new HashMapString, SoftReference();imageView1 = (android.widget.ImageView) this.findViewById(R.id.image1);imageView2 = (android.widget.ImageView) this.findViewById(R.id.image2);imageView3 = (android.widget.ImageView) this.findViewById(R.id.image3);public void btn1(View v) imgpath = receive(path);loadImage(imgpath, R.id.image1);public void btn2(View v) imgpath = receive(path);loadImage(imgpath, R.id.image2);public void btn3(View v) imgpath = receive(path);loadImage(imgpath, R.id.image3);/ 从服务端得到图片地址urlpublic void loadImage(String url, int id) loder = new AsyncImageLoader();ImageView imageView = (ImageView) this.findViewById(id);callback = new Callbackimg(imageView);Drawable drawable = loder.loadDrawable(url);if (drawable != null) imageView.setImageDrawable(drawable);public String receive(String path) try / 服务器Url对象.URL url = new .URL(path);.HttpURLConnection httpConnection = (.HttpURLConnection) url.openConnection();/ 设置连接延时 可根据情况修改httpConnection.setConnectTimeout(5000);httpConnection.setDoInput(true);httpConnection.setDoOutput(true);/ POST方式发送 如果发送Object必须用POST方式httpConnection.setRequestMethod(POST);httpConnection.connect();/ 输入流 这里可以获取服务器返回结果 以判断图片是否上传成功 如需要 自行完成java.io.InputStreamReader inReader = new java.io.InputStreamReader(httpConnection.getInputStream();java.io.BufferedReader buffer = new java.io.BufferedReader(inReader);str = buffer.readLine();System.out.println(str); catch (Exception ex) ex.printStackTrace();return str;/ 异步下载缓存到HashMapclass AsyncImageLoader public Drawable loadDrawable(final String imageUrl) if (hashmap.containsKey(imageUrl) ;/ 判断是否缓存如果缓存里执行此代码SoftReference softReference = hashmap.get(imageUrl);Drawable drawable = softReference.get();if (drawable != null) return drawable; else final Handler handler = new Handler() public void handleMessage(Message message) callback.imageLoaded(Drawable) message.obj, imageUrl);new Thread() / 下载后将图片放进hashmap里public void run() Drawable drawable = loadImageFromUrl(imageUrl);hashmap.put(imageUrl, new SoftReference(drawable););Message message = handler.obtainMessage(0, drawable);handler.sendMessage(message);.start();return null;public Drawable loadImageFromUrl(String url) / 根据url得到图片Drawable d = null;InputStream i = null;URL m;try m = new URL(url);i = (InputStream) m.getContent(); catch (MalformedURLException e) e.printStackTrace(); catch (IOException e) e.printStackTrace();d = Drawable.createFromStream(i, src);/ ?return d;public interface ImageCallback / 通过接口图片下载成功后进行此方法public void imageLoaded(Drawable imageDrawable, String imageUrl);class Callbackimg implements com.down.LazyLoadImageActivity.ImageCallbac