Ich zeige Bilder und etwas Text in einer Listenansicht mit einem Adapter an. Die Bilder werden aus dem Internet gezogen, dann lokal zwischengespeichert und angezeigt. Die Bilder sind bereits klein (60px Quadrat), und ich kenne ihre Größe, also verwende ich die advice from here suggesting I use setImageURI instead of decoding the bitmap.Warum funktioniert ImageView.setImageURI() in Android 2.2, aber nicht in 2.1?
Die Klasse, die die Arbeit tut, ist eine modifizierte Version von ImageLoader
Der Code des Fedor legt einen Stub ziehbar zum Image bis das gewünschte Bild aus dem Internet heruntergeladen wird, lädt dann die zwischengespeicherte Datei aus dem sdcard. In Android 2.2 funktioniert das gut. Es ist schnell und ich bekomme keine Abstürze von OOM. Am 2.1, ich folgende Fehlermeldung jedoch erhalten:
09-15 11:04:52.993: INFO/System.out(240): resolveUri failed on bad bitmap uri: file:///sdcard/android/data/com.example.myapp/cache/4164137
Die Imageloader-Klasse wird wie folgt dar:
/*
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied. See the License for the
specific language governing permissions and limitations
under the License.
*/
public class ImageLoader {
//the simplest in-memory cache implementation. This should be replaced with something like SoftReference or BitmapOptions.inPurgeable(since 1.6)
private HashMap<String, Uri> cache=new HashMap<String, Uri>();
private File cacheDir;
public ImageLoader(Context context){
//Make the background thead low priority. This way it will not affect the UI performance
photoLoaderThread.setPriority(Thread.NORM_PRIORITY-1);
//Find the dir to save cached images
if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
cacheDir=new File(android.os.Environment.getExternalStorageDirectory(),"Android/data/com.droidicon.launcherproicons/cache/");
else
cacheDir=context.getCacheDir();
if(!cacheDir.exists())
cacheDir.mkdirs();
}
final int stub_id=R.drawable.loading;
public void DisplayImage(String url, Activity activity, ImageView imageView, int scaleSize)
{
if(cache.containsKey(url))
imageView.setImageURI(cache.get(url));
else
{
queuePhoto(url, activity, imageView, scaleSize);
imageView.setImageResource(stub_id);
}
}
private void queuePhoto(String url, Activity activity, ImageView imageView, int scaleSize)
{
//This ImageView may be used for other images before. So there may be some old tasks in the queue. We need to discard them.
photosQueue.Clean(imageView);
PhotoToLoad p=new PhotoToLoad(url, imageView, scaleSize);
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.push(p);
photosQueue.photosToLoad.notifyAll();
}
//start thread if it's not started yet
if(photoLoaderThread.getState()==Thread.State.NEW)
photoLoaderThread.start();
}
private Uri getUri(String url, int scaleSize){
if(url != ""){
//I identify images by hashcode. Not a perfect solution, good for the demo.
// try{
String filename=String.valueOf(url.hashCode());
File f=new File(cacheDir, filename);
//from SD cache
if(f.exists()){
Uri b = Uri.fromFile(f);
System.out.println(f.toString());
return b;
}
//from web
try {
Uri bitmap=null;
InputStream is=new URL(url).openStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
bitmap = Uri.fromFile(f);
System.out.println(f.toString());
return bitmap;
} catch (Exception ex){
ex.printStackTrace();
return null;
}
} else {
return null;
}
}
//Task for the queue
private class PhotoToLoad
{
public String url;
public ImageView imageView;
public int scaleSize;
public PhotoToLoad(String u, ImageView i, int ss){
url=u;
imageView=i;
scaleSize=ss;
}
}
PhotosQueue photosQueue=new PhotosQueue();
public void stopThread()
{
photoLoaderThread.interrupt();
}
//stores list of photos to download
class PhotosQueue
{
private Stack<PhotoToLoad> photosToLoad=new Stack<PhotoToLoad>();
//removes all instances of this ImageView
public void Clean(ImageView image)
{
for(int j=0 ;j<photosToLoad.size();){
if(photosToLoad.get(j).imageView==image)
photosToLoad.remove(j);
else
++j;
}
}
}
class PhotosLoader extends Thread {
public void run() {
try {
while(true)
{
//thread waits until there are any images to load in the queue
if(photosQueue.photosToLoad.size()==0)
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.wait();
}
if(photosQueue.photosToLoad.size()!=0)
{
PhotoToLoad photoToLoad;
synchronized(photosQueue.photosToLoad){
photoToLoad=photosQueue.photosToLoad.pop();
}
Uri bmp=getUri(photoToLoad.url, photoToLoad.scaleSize);
cache.put(photoToLoad.url, bmp);
if(((String)photoToLoad.imageView.getTag()).equals(photoToLoad.url)){
UriDisplayer bd=new UriDisplayer(bmp, photoToLoad.imageView);
Activity a=(Activity)photoToLoad.imageView.getContext();
a.runOnUiThread(bd);
}
}
if(Thread.interrupted())
break;
}
} catch (InterruptedException e) {
//allow thread to exit
}
}
}
PhotosLoader photoLoaderThread=new PhotosLoader();
class UriDisplayer implements Runnable
{
Uri uri;
ImageView imageView;
public UriDisplayer(Uri u, ImageView i){uri=u;imageView=i;}
public void run() {
File f = new File(uri.getPath());
if(f.exists()){
imageView.setImageURI(uri);
} else {
imageView.setImageResource(stub_id);
}
}
}
public void clearCache() {
//clear memory cache
cache.clear();
//clear SD cache
File[] files=cacheDir.listFiles();
for(File f:files)
f.delete();
}
}
Hier ist einer des Adapters, der diesen Imageloader implementiert:
public class ColorAdapter extends ArrayAdapter<Color> {
private Activity activity;
private int resource;
private String response;
private Context context;
public ImageLoader imageLoader;
public ColorAdapter(Activity a, Context context, int resource, List<Color> items){
super(context, resource, items);
this.resource=resource;
imageLoader=new ImageLoader(context);
activity = a;
}
@Override
public View getView(int position, View convertView, ViewGroup parent){
Color color = getItem(position);
String minflater = Context.LAYOUT_INFLATER_SERVICE;
LayoutInflater inflater;
inflater = (LayoutInflater)getContext().getSystemService(minflater);
ViewHolder holder;
if(convertView==null){
convertView = inflater.inflate(R.layout.listcolors, parent, false);
holder=new ViewHolder();
holder.txtName=(TextView)convertView.findViewById(R.id.txtName);
//holder.txtUser=(TextView)convertView.findViewById(R.id.txtUser);
holder.imgColorImg=(ImageView)convertView.findViewById(R.id.imgColorImg);
convertView.setTag(holder);
}
else
holder=(ViewHolder)convertView.getTag();
holder.txtName.setText(color.getName());
//holder.txtUser.setText(dock.getUser());
holder.imgColorImg.setTag(color.getIconURL());
imageLoader.DisplayImage(color.getIconURL(), activity, holder.imgColorImg, 84);
return convertView;
}
class ViewHolder{
TextView txtName;
//TextView txtUser;
ImageView imgColorImg;
}
}
Derselbe Fix sollte auf Uri angewendet werden b = Uri.fromFile (f); Zeile in getUri-Methode –