Android實現Listview非同步載入網狀圖片並動態更新的方法_Android

本文執行個體講述了Android實現Listview非同步載入網狀圖片並動態更新的方法。分享給大家供大家參考，具體如下：

應用執行個體：解析後台返回的資料，把每條都顯示在ListView中，包括活動圖表片、店名、活動詳情、地址、電話和距離等。

在布局檔案中ListView的定義：

<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"/>

在布局檔案ListViewItem,中定義活動圖表片、店名、活動詳情、地址、電話和距離的布局

<?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)定義類MapListImageAndText管理ListViewItem中控制項的內容

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)定義類MapListViewCache執行個體化ListViewItem中的控制項

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)定義類AsyncImageLoader,開啟線程下載指定圖片

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)定義類MapListImageAndTextListAdapter繼承ArrayAdapter,用於建立AsyncImageLoader執行個體,並指定控制項的內容

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, 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)主程式中Listview與MapListImageAndTextListAdapter的捆綁

//tuangoupoints為對後台傳回來的資料解析後得到的字串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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希望本文所述對大家Android程式設計有所協助。