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);