下面的类解析一个 rss 提要并使用 AsyncTask 在屏幕上绘制图像/文本。我正在使用美国国家航空航天局的 RSS 提要。昨晚我切换到相同的提要，但图像更大。现在，当我尝试按下刷新按钮时，它会耗尽内存。我该如何处理？我知道这只是因为图像太大（大约 6mb，而另一张图像为 36kb）而且我读到它是静态的也无济于事。我看不出它是静态的，因为当您将壁纸设置为图像时，我需要检索 final_image 作为该类的单独实例。因此，下面的所有内容都适用于较小的图像。对于大图像，它可以工作一次，但如果您尝试按下刷新按钮（仅运行 RssParseSync.execute()），则无法刷新，并且出现以下错误。
public class RssParseSync extends AsyncTask<String,String,Bitmap>{
private Activity parent;
private ProgressDialog dialog;
private static Bitmap final_image; //must be static because a new instance is required to access getFinalImage();
public RssParseSync(Activity parent){this.parent =parent;}//constructor to pass parent activity, need this to call findViewById
private XmlPullParser makeParser(){
}
@Override
protected Bitmap doInBackground(String... info){
URL iotd;
int count=info.length;
String title="",link="",description="",date="";
System.out.println("Number of params is "+count);
try{
iotd = new URL("http://www.nasa.gov/rss/lg_image_of_the_day.rss");//set URl
BufferedReader in;//new BufferedReader
in = new BufferedReader(new InputStreamReader(iotd.openStream()));//get rss
XmlPullParserFactory factory;
factory = XmlPullParserFactory.newInstance();//new factory
factory.setNamespaceAware(true);
XmlPullParser xpp;
xpp = factory.newPullParser();
xpp.setInput(in);
//rss is now parsed, free to use XmlPullParser functions to move around and evaulate the rss
int eventType;
eventType = xpp.getEventType();//returns an int which mean different things (START_DOCUMENT,START_TAG,etc)
while(eventType!=XmlPullParser.END_DOCUMENT){//while the document has words
switch(eventType){
case XmlPullParser.START_DOCUMENT://beginning of xml
break;
case XmlPullParser.START_TAG://case : at beginning of new tag
String tagName=xpp.getName();
System.out.println(tagName+" "+xpp.getDepth());
if(tagName.equals("title")&& xpp.getDepth()==4){//depth is specific to this certain rss feed, there are multiple tags with the same names
info[0]=xpp.nextText();
title=info[0];
}
if(tagName.equals("description")&& xpp.getDepth()==4){//depth is specific to this certain rss feed, there are multiple tags with the same names
info[1]=xpp.nextText();
description=info[1];
StringBuilder tabbed=new StringBuilder(description);
tabbed.insert(0, "\t");
description=tabbed.toString();
//info[1]=description;
}
if(tagName.equals("pubDate")){//no depth needed, only one tag is named pubDate
info[2]=xpp.nextText();
date=info[2];
}
if(tagName.equals("enclosure")&&xpp.getDepth()==4){//this is where our image url is. this url is an attribute of the "enclosure" tag
//System.out.println("Enclosure has "+xpp.getAttributeCount());
for(int i=0; i<=xpp.getAttributeCount()-1; i++){
System.out.println("in for");
if(xpp.getAttributeName(i).equals("url")){
link=xpp.getAttributeValue(i);
info[3]=link;
//System.out.println(link);
}
}
}
break;
}
eventType=xpp.next();
}//switch
publishProgress(title,description,date,link);
in.close();//close BufferedReader
} catch (MalformedURLException e){
e.printStackTrace();
}catch(XmlPullParserException e1){
e1.printStackTrace();
}catch(IOException e2){
e2.printStackTrace();
}
Bitmap image=getBitmapFromURL(info[3]);
return image;
}
@Override
protected void onProgressUpdate(String... progress){
try {
System.out.println("onProgressUpdate");
resetDisplay(progress[0],progress[1],progress[2],progress[3]);//feeding parsed rss values, title, description, date, and link
} catch (MalformedURLException e) {//both exceptions are thrown by resetDisplay
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
protected void onPostExecute(Bitmap image){//error when doing this in resetDisplay.... onPostExecute is invoked by the ui thread so this may be why it works here and not in resetDisplay
ImageView imageView=(ImageView) parent.findViewById(R.id.imageDisplay);
imageView.setImageBitmap(image);
final_image=image;
dialog.dismiss();
}
protected void onPreExecute(){
dialog=ProgressDialog.show(parent, "Loading", "Loading the image of the day");
}
private void resetDisplay(String title, String description,String date, String link) throws MalformedURLException, IOException{
TextView titleView=(TextView) parent.findViewById(R.id.imageTitle);
titleView.setText(title);
TextView dateView=(TextView) parent.findViewById(R.id.imageDate);
dateView.setText(date);
TextView descriptionView=(TextView) parent.findViewById(R.id.imageDescription);
descriptionView.setText(description);
}
public Bitmap getBitmapFromURL(String url) {
try {
Bitmap bitmap=null;
InputStream input = new java.net.URL(url).openStream();
bitmap = BitmapFactory.decodeStream(input);//Decode an input stream into a bitmap. If the input stream is null, or cannot be used to decode a bitmap, the function returns null.
input.close();
return bitmap;
} catch (IOException ioe) { return null; }
}
public Bitmap getFinalImage(){
return final_image;
};
}//class
刷新方法
public void onRefresh(){
System.out.println("in onRefresh");
new RssParseSync(getActivity()).execute(title,description,date,link);
}
Logcat 日志
07-20 17:44:18.470: I/System.out(7581): onProgressUpdate
07-20 17:44:18.770: D/dalvikvm(7581): GC_FOR_ALLOC freed 190K, 3% free 26538K/27299K, paused 46ms
07-20 17:44:18.770: I/dalvikvm-heap(7581): Forcing collection of SoftReferences for 24107536-byte allocation
07-20 17:44:18.790: D/dalvikvm(7581): GC_BEFORE_OOM freed 18K, 3% free 26519K/27299K, paused 23ms
07-20 17:44:18.790: E/dalvikvm-heap(7581): Out of memory on a 24107536-byte allocation.
07-20 17:44:18.790: I/dalvikvm(7581): "AsyncTask #2" prio=5 tid=13 RUNNABLE
07-20 17:44:18.790: I/dalvikvm(7581): | group="main" sCount=0 dsCount=0 obj=0x40d6cac8 self=0x2412840
07-20 17:44:18.790: I/dalvikvm(7581): | sysTid=7646 nice=10 sched=0/0 cgrp=default handle=32889544
07-20 17:44:18.790: I/dalvikvm(7581): | schedstat=( 0 0 0 ) utm=7 stm=0 core=1
07-20 17:44:18.790: I/dalvikvm(7581): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
07-20 17:44:18.800: I/dalvikvm(7581): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:719)
07-20 17:44:18.800: I/dalvikvm(7581): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:791)
07-20 17:44:18.800: I/dalvikvm(7581): at com.wajumbie.nasadailyimage.RssParseSync.getBitmapFromURL(RssParseSync.java:162)
07-20 17:44:18.800: I/dalvikvm(7581): at com.wajumbie.nasadailyimage.RssParseSync.doInBackground(RssParseSync.java:116)
07-20 17:44:18.800: I/dalvikvm(7581): at com.wajumbie.nasadailyimage.RssParseSync.doInBackground(RssParseSync.java:1)
07-20 17:44:18.800: I/dalvikvm(7581): at android.os.AsyncTask$2.call(AsyncTask.java:264)
07-20 17:44:18.800: I/dalvikvm(7581): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-20 17:44:18.800: I/dalvikvm(7581): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-20 17:44:18.800: I/dalvikvm(7581): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
07-20 17:44:18.800: I/dalvikvm(7581): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-20 17:44:18.800: I/dalvikvm(7581): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-20 17:44:18.800: I/dalvikvm(7581): at java.lang.Thread.run(Thread.java:864)
07-20 17:44:18.800: E/dalvikvm(7581): Out of memory: Heap Size=34019KB, Allocated=26519KB, Limit=49152KB
07-20 17:44:18.800: E/dalvikvm(7581): Extra info: Footprint=27299KB, Allowed Footprint=34019KB, Trimmed=1212KB
07-20 17:44:18.800: D/skia(7581): --- decoder->decode returned false
07-20 17:44:18.800: W/dalvikvm(7581): threadid=13: thread exiting with uncaught exception (group=0x40aa3a08)
07-20 17:44:18.810: E/AndroidRuntime(7581): FATAL EXCEPTION: AsyncTask #2
07-20 17:44:18.810: E/AndroidRuntime(7581): java.lang.RuntimeException: An error occured while executing doInBackground()
07-20 17:44:18.810: E/AndroidRuntime(7581): at android.os.AsyncTask$3.done(AsyncTask.java:278)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-20 17:44:18.810: E/AndroidRuntime(7581): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.lang.Thread.run(Thread.java:864)
07-20 17:44:18.810: E/AndroidRuntime(7581): Caused by: java.lang.OutOfMemoryError: (Heap Size=34019KB, Allocated=26519KB)
07-20 17:44:18.810: E/AndroidRuntime(7581): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
07-20 17:44:18.810: E/AndroidRuntime(7581): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:719)
07-20 17:44:18.810: E/AndroidRuntime(7581): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:791)
07-20 17:44:18.810: E/AndroidRuntime(7581): at com.wajumbie.nasadailyimage.RssParseSync.getBitmapFromURL(RssParseSync.java:162)
07-20 17:44:18.810: E/AndroidRuntime(7581): at com.wajumbie.nasadailyimage.RssParseSync.doInBackground(RssParseSync.java:116)
07-20 17:44:18.810: E/AndroidRuntime(7581): at com.wajumbie.nasadailyimage.RssParseSync.doInBackground(RssParseSync.java:1)
07-20 17:44:18.810: E/AndroidRuntime(7581): at android.os.AsyncTask$2.call(AsyncTask.java:264)
07-20 17:44:18.810: E/AndroidRuntime(7581): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-20 17:44:18.810: E/AndroidRuntime(7581): ... 5 more
07-20 17:44:19.061: D/OpenGLRenderer(7581): Flushing caches (mode 0)
07-20 17:44:19.061: D/memalloc(7581): ion: Unmapping buffer base:0x52738000 size:2088960
07-20 17:44:19.061: D/memalloc(7581): ion: Unmapping buffer base:0x52f7c000 size:2088960
07-20 17:44:19.061: D/memalloc(7581): ion: Unmapping buffer base:0x53477000 size:2088960
07-20 17:44:19.081: D/OpenGLRenderer(7581): Flushing caches (mode 0)
07-20 17:44:19.111: D/memalloc(7581): ion: Unmapping buffer base:0x52bea000 size:524288
07-20 17:44:19.121: D/memalloc(7581): ion: Unmapping buffer base:0x5367d000 size:524288
07-20 17:44:19.121: D/memalloc(7581): ion: Unmapping buffer base:0x53326000 size:524288
07-20 17:44:19.141: D/OpenGLRenderer(7581): Flushing caches (mode 2)
07-20 17:44:19.181: E/WindowManager(7581): Activity com.wajumbie.nasadailyimage.NasaAppActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40d92b30 that was originally added here
07-20 17:44:19.181: E/WindowManager(7581): android.view.WindowLeaked: Activity com.wajumbie.nasadailyimage.NasaAppActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40d92b30 that was originally added here
07-20 17:44:19.181: E/WindowManager(7581): at android.view.ViewRootImpl.<init>(ViewRootImpl.java:380)
07-20 17:44:19.181: E/WindowManager(7581): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:372)
07-20 17:44:19.181: E/WindowManager(7581): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:320)
07-20 17:44:19.181: E/WindowManager(7581): at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:152)
07-20 17:44:19.181: E/WindowManager(7581): at android.view.Window$LocalWindowManager.addView(Window.java:557)
07-20 17:44:19.181: E/WindowManager(7581): at android.app.Dialog.show(Dialog.java:301)
07-20 17:44:19.181: E/WindowManager(7581): at android.app.ProgressDialog.show(ProgressDialog.java:116)
07-20 17:44:19.181: E/WindowManager(7581): at android.app.ProgressDialog.show(ProgressDialog.java:99)
07-20 17:44:19.181: E/WindowManager(7581): at android.app.ProgressDialog.show(ProgressDialog.java:94)
07-20 17:44:19.181: E/WindowManager(7581): at com.wajumbie.nasadailyimage.RssParseSync.onPreExecute(RssParseSync.java:142)
07-20 17:44:19.181: E/WindowManager(7581): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:561)
07-20 17:44:19.181: E/WindowManager(7581): at android.os.AsyncTask.execute(AsyncTask.java:511)
07-20 17:44:19.181: E/WindowManager(7581): at com.wajumbie.nasadailyimage.NasaDailyImage.onRefresh(NasaDailyImage.java:57)
07-20 17:44:19.181: E/WindowManager(7581): at com.wajumbie.nasadailyimage.NasaAppActivity$1.run(NasaAppActivity.java:48)
07-20 17:44:19.181: E/WindowManager(7581): at com.wajumbie.nasadailyimage.NasaAppActivity.onRefreshClicked(NasaAppActivity.java:51)
07-20 17:44:19.181: E/WindowManager(7581): at java.lang.reflect.Method.invokeNative(Native Method)
07-20 17:44:19.181: E/WindowManager(7581): at java.lang.reflect.Method.invoke(Method.java:511)
07-20 17:44:19.181: E/WindowManager(7581): at android.view.View$1.onClick(View.java:3066)
07-20 17:44:19.181: E/WindowManager(7581): at android.view.View.performClick(View.java:3538)
07-20 17:44:19.181: E/WindowManager(7581): at android.view.View$PerformClick.run(View.java:14330)
07-20 17:44:19.181: E/WindowManager(7581): at android.os.Handler.handleCallback(Handler.java:607)
07-20 17:44:19.181: E/WindowManager(7581): at android.os.Handler.dispatchMessage(Handler.java:92)
07-20 17:44:19.181: E/WindowManager(7581): at android.os.Looper.loop(Looper.java:156)
07-20 17:44:19.181: E/WindowManager(7581): at android.app.ActivityThread.main(ActivityThread.java:5008)
07-20 17:44:19.181: E/WindowManager(7581): at java.lang.reflect.Method.invokeNative(Native Method)
07-20 17:44:19.181: E/WindowManager(7581): at java.lang.reflect.Method.invoke(Method.java:511)
07-20 17:44:19.181: E/WindowManager(7581): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
07-20 17:44:19.181: E/WindowManager(7581): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
07-20 17:44:19.181: E/WindowManager(7581): at dalvik.system.NativeStart.main(Native Method)