本文實(shí)例講述了Android實(shí)現(xiàn)Listview異步加載網(wǎng)絡(luò)圖片并動(dòng)態(tài)更新的方法。分享給大家供大家參考,具體如下:
應(yīng)用實(shí)例:解析后臺(tái)返回的數(shù)據(jù),把每條都顯示在ListView中,包括活動(dòng)圖片、店名、活動(dòng)詳情、地址、電話(huà)和距離等。
在布局文件中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"/>
在布局文件ListViewItem,中定義活動(dòng)圖片、店名、活動(dòng)詳情、地址、電話(huà)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(lèi)MapListImageAndText管理ListViewItem中控件的內(nèi)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(lèi)MapListViewCache實(shí)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)定義類(lèi)AsyncImageLoader,開(kāi)啟線(xiàn)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(lèi)MapListImageAndTextListAdapter繼承ArrayAdapter,用于創(chuàng)建AsyncImageLoader實(shí)例,并指定控件的內(nèi)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)主程序中Listview與MapListImageAndTextListAdapter的捆綁
//tuangoupoints為對(duì)后臺(tái)傳回來(lái)的數(shù)據(jù)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);更多關(guān)于A(yíng)ndroid相關(guān)內(nèi)容感興趣的讀者可查看本站專(zhuān)題:《Android視圖View技巧總結(jié)》、《Android編程之a(chǎn)ctivity操作技巧總結(jié)》、《Android操作SQLite數(shù)據(jù)庫(kù)技巧總結(jié)》、《Android操作json格式數(shù)據(jù)技巧總結(jié)》、《Android數(shù)據(jù)庫(kù)操作技巧總結(jié)》、《Android文件操作技巧匯總》、《Android編程開(kāi)發(fā)之SD卡操作方法匯總》、《Android開(kāi)發(fā)入門(mén)與進(jìn)階教程》、《Android資源操作技巧匯總》及《Android控件用法總結(jié)》
希望本文所述對(duì)大家Android程序設(shè)計(jì)有所幫助。
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