Android Listview异步动态加载网络图片

1.定义类MapListImageAndText管理ListViewItem中控件的内容

package com.google.zxing.client.android.AsyncLoadImage;
 
 
 
public class MapListImageAndText {
        private String imageUrl;
        private String shopname;
        private String activitynifo;
        private String address;
        private String telephone;
        private String distance;
         
        public MapListImageAndText(String imageUrl, String shopname, String activitynifo, String address, String telephone,String distance) {
            this.imageUrl = imageUrl;
            this.shopname = shopname;
            this.activitynifo = activitynifo;
            this.address = address;
            this.telephone = telephone;
            this.distance=distance;
        }
 
        public String getImageUrl() {
            return imageUrl;
        }
         
        public String getShopname() {
            return shopname;
        }
 
        public String getActivitynifo() {
            return activitynifo;
        }
 
        public String getAddress() {
            return address;
        }
 
        public String getTelephone() {
            return telephone;
        }
         
        public String getDistance() {
            return distance;
        }
 
         
}

2. 定义类MapListViewCache实例化ListViewItem中的控件     

package com.google.zxing.client.android.AsyncLoadImage;
 
import com.google.zxing.client.android.R;
 
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
 
public class MapListViewCache {
 
        private View baseView;
        private TextView shopname;
        private TextView activitynifo;
        private TextView address;
        private TextView telephone;
        private TextView distance;
 
        private ImageView imageView;
 
        public MapListViewCache(View baseView) {
            this.baseView = baseView;
        }
 
        public TextView getShopname() {
            if (shopname == null) {
                shopname = (TextView) baseView.findViewById(R.id.maplistviewitemshopname);
            }
            return shopname;
        }
         
        public TextView getActivitynifo() {
            if (activitynifo == null) {
                activitynifo = (TextView) baseView.findViewById(R.id.maplistviewitemActi);
            }
            return activitynifo;
        }
         
        public TextView getAddress() {
            if (address == null) {
                address = (TextView) baseView.findViewById(R.id.maplistviewitemaddr);
            }
            return address;
        }
         
        public TextView getTelephone() {
            if (telephone == null) {
                telephone = (TextView) baseView.findViewById(R.id.maplistviewitemtelphone);
            }
            return telephone;
        }
 
        public ImageView getImageView() {
            if (imageView == null) {
                imageView = (ImageView) baseView.findViewById(R.id.maplistviewitemImage);
            }
            return imageView;
        }
         
        public TextView getDistance() {
            if (distance == null) {
                distance = (TextView) baseView.findViewById(R.id.maplistviewitemdistance);
            }
            return distance;
        }
 
}

3. 定义类AsyncImageLoader,开启线程下载指定图片

package com.google.zxing.client.android.AsyncLoadImage;
 
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;
 
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.Message;
 
public class AsyncImageLoader {
 
     private HashMap<String, SoftReference<Drawable>> imageCache;
       
         public AsyncImageLoader() {
             imageCache = new HashMap<String, SoftReference<Drawable>>();
         }
       
         public Drawable loadDrawable(final String imageUrl, final ImageCallback imageCallback) {
             if (imageCache.containsKey(imageUrl)) {
                 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, imageUrl);
                 }
             };
             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;
        }
       
         public interface ImageCallback {
             public void imageLoaded(Drawable imageDrawable, String imageUrl);
         }
 
}

4. 定义类MapListImageAndTextListAdapter继承ArrayAdapter  

package com.google.zxing.client.android.AsyncLoadImage;
 
import java.util.List;
 
import com.google.zxing.client.android.R;
 
import com.google.zxing.client.android.AsyncLoadImage.AsyncImageLoader.ImageCallback;
 
import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
 
public class MapListImageAndTextListAdapter extends ArrayAdapter<MapListImageAndText> {
 
        private ListView listView;
        private AsyncImageLoader asyncImageLoader;
 
        public MapListImageAndTextListAdapter(Activity activity, List<MapListImageAndText> imageAndTexts, ListView listView) {
            super(activity, 0, imageAndTexts);
            this.listView = listView;
            asyncImageLoader = new AsyncImageLoader();
        }
 
        public View getView(int position, View convertView, ViewGroup parent) {
            Activity activity = (Activity) getContext();
 
            // Inflate the views from XML
            View rowView = convertView;
            MapListViewCache viewCache;
            if (rowView == null) {
                LayoutInflater inflater = activity.getLayoutInflater();
                rowView = inflater.inflate(R.layout.maplistviewitem, null);
                viewCache = new MapListViewCache(rowView);
                rowView.setTag(viewCache);
            } else {
                viewCache = (MapListViewCache) rowView.getTag();
            }
            MapListImageAndText imageAndText = getItem(position);
 
            // Load the image and set it on the ImageView
            String imageUrl = imageAndText.getImageUrl();
            ImageView imageView = viewCache.getImageView();
            imageView.setTag(imageUrl);
            Drawable cachedImage = asyncImageLoader.loadDrawable(imageUrl, new ImageCallback() {
                 
                 
                public void imageLoaded(Drawable imageDrawable, String imageUrl) {
                    ImageView imageViewByTag = (ImageView) listView.findViewWithTag(imageUrl);
                    if (imageViewByTag != null) {
                        imageViewByTag.setImageDrawable(imageDrawable);
                    }
                }
            });
            if (cachedImage == null) {
                imageView.setImageResource(R.drawable.refresh);
            }else{
                imageView.setImageDrawable(cachedImage);
            }
            // Set the text on the TextView
            TextView shopname = viewCache.getShopname();
            shopname.setText(imageAndText.getShopname());
             
            TextView activitynifo = viewCache.getActivitynifo();
            activitynifo.setText(imageAndText.getActivitynifo());
             
            TextView address = viewCache.getAddress();
            address.setText(imageAndText.getAddress());
             
            TextView telephone = viewCache.getTelephone();
            telephone.setText(imageAndText.getTelephone());
             
            TextView distance = viewCache.getDistance();
            distance.setText(imageAndText.getDistance());
             
            return rowView;
        }
 
}

5.主程序中Listview与MapListImageAndTextListAdapter的捆绑     

//tuangoupoints为对后台传回来的数据解析后得到的字符串
String[] mtuangoupoints =tuangoupoints.split("@");
 
List<MapListImageAndText> dataArray=new ArrayList<MapListImageAndText>();
     
for(int i=0; i<mtuangoupoints.length;i++){
    String[] tonepoint=mtuangoupoints[i].split("#");
     
    String shopname=String.valueOf(i+1)+tonepoint[2];
    String activityinfo=tonepoint[1];
    String address=tonepoint[6];
    String telephone=tonepoint[7];
    String imageurl=tonepoint[8];
    String distance=tonepoint[5];
     
    MapListImageAndText test=new MapListImageAndText(imageurl,shopname,activityinfo,address,telephone,distance);
    dataArray.add(test);
}
     
MapListImageAndTextListAdapter adapter=new MapListImageAndTextListAdapter(this, dataArray, mlistView);
mlistView.setAdapter(adapter);