Android realizes listview asynchronous Load network picture and dynamically updates the method _android

This article describes the Android implementation ListView asynchronous loading of network pictures and dynamic update methods. Share to everyone for your reference, specific as follows:

Application Example: Parsing the data returned in the background, each display in the ListView, including the activity picture, store name, activity details, address, telephone and distance.

Definition of ListView in Layout file:

<listview
android: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"
/>

Define the layout of the active picture, store name, activity details, address, phone, and distance in the layout file ListViewItem

<?xml version= "1.0" encoding= "Utf-8"?> <relativelayout android: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 "> <imageview android:paddingtop= "2dip" android:layout_alignparentleft= "true" android:layout_width= "80px" android:layout_height = "80px" android:id= "@+id/maplistviewitemimage"/> <textview android:layout_height= "Wrap_content" Android: Textsize= "17dip" android:layout_width= "fill_parent" android:id= "@+id/maplistviewitemshopname" Android:layout_ torightof= "@id/maplistviewitemimage" android:textcolor= "#000000"/> <textview android: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 "/> <TExtview android:layout_height= "wrap_content" android:layout_width= "Fill_parent" True "android:layout_below=" @+id/maplistviewitemacti "android:id=" @+id/maplistviewitemaddr "android:textColor=" # 6C6C6C "android:singleline=" true "/> <textview android: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) Defines the contents of the control in the ListViewItem class Maplistimageandtext management

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) to define a class Maplistviewcache to instantiate a control in ListViewItem

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.fin
      Dviewbyid (R.ID.MAPLISTVIEWITEMACTI);
    return ACTIVITYNIFO; Public TextView getaddress () {if (address = = NULL) {address = (TextView) Baseview.findviewbyid (R.ID.MAPLISTVIEWITEMADDR);
    return to 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.findviewby
      Id (R.id.maplistviewitemimage);
    return ImageView; Public TextView getdistance () {if (distance = null) {distance = (TextView) Baseview.findviewbyid (R.
      Id.maplistviewitemdistance);
    return distance;

 }
}

(3) Define class Asyncimageloader, open thread download specified picture

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.cont
         Ainskey (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);

}
} 

The

(4) Defines the class Maplistimageandtextlistadapter inheritance Arrayadapter, which is used to create the Asyncimageloader instance and specify the contents of the control

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 Listvie
    W
    Private Asyncimageloader Asyncimageloader; Public Maplistimageandtextlistadapter, 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 (Drawa 
    Ble 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) Binding of ListView and Maplistimageandtextlistadapter in the main program

Tuangoupoints the string
string[] mtuangoupoints =tuangoupoints.split ("@") after parsing the data returned by the background;
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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I hope this article will help you with the Android program.