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);