Android实现Listview异步加载网络图片并动态更新的方法

概述本文实例讲述了Android实现Listview异步加载网络图片并动态更新的方法。分享给大家供大家参考，具体如下：

本文实例讲述了AndroID实现ListvIEw异步加载网络图片并动态更新的方法。分享给大家供大家参考，具体如下：

应用实例：解析后台返回的数据，把每条都显示在ListVIEw中，包括活动图片、店名、活动详情、地址、电话和距离等。

在布局文件中ListVIEw的定义：

<ListVIEwandroID:ID="@ID/mapListvIEw" androID:background="@drawable/bg" androID:layout_wIDth="fill_parent" androID:layout_height="fill_parent" androID:cachecolorHint="#00000000" androID:divIDer="@drawable/separator" androID:divIDerHeight="2.0px" androID:layout_below="@ID/mapseparator"/>

在布局文件ListVIEwItem,中定义活动图片、店名、活动详情、地址、电话和距离的布局

<?xml version="1.0" enCoding="utf-8"?><relativeLayoutandroID:ID="@+ID/relativeLayout01" androID:layout_wIDth="fill_parent" xmlns:androID="http://schemas.androID.com/apk/res/androID"androID:layout_height="wrap_content" androID:paddingBottom="2dip" androID:paddingleft="2dip" androID:paddingRight="2dip"><ImageVIEwandroID:paddingtop="2dip" androID:layout_alignParentleft="true" androID:layout_wIDth="80px" androID:layout_height="80px" androID:ID="@+ID/mapListvIEwitemImage"/><TextVIEwandroID:layout_height="wrap_content" androID:textSize="17dip" androID:layout_wIDth="fill_parent" androID:ID="@+ID/mapListvIEwitemshopname"androID:layout_toRightOf="@ID/mapListvIEwitemImage"androID:textcolor="#000000"/><TextVIEwandroID:layout_height="wrap_content" androID:layout_wIDth="fill_parent" androID:layout_alignParentleft="true" androID:layout_below="@+ID/mapListvIEwitemImage" androID:ID="@+ID/mapListvIEwitemActi" androID:textcolor="#6C6C6C"/><TextVIEwandroID:layout_height="wrap_content" androID:layout_wIDth="fill_parent" androID:layout_alignParentleft="true" androID:layout_below="@+ID/mapListvIEwitemActi" androID:ID="@+ID/mapListvIEwitemaddr" androID:textcolor="#6C6C6C" androID:singleline="true"/><TextVIEwandroID:layout_height="wrap_content" androID:layout_wIDth="fill_parent" androID:layout_alignParentleft="true" androID:layout_below="@+ID/mapListvIEwitemaddr" androID:ID="@+ID/mapListvIEwitemtelphone" androID:textcolor="#6C6C6C" androID:singleline="true"/></relativeLayout>

(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,用于创建AsyncImageLoader实例,并指定控件的内容

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,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);

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