我有四个同步任务，它们从onCreateView()片段执行，这些线程正在从服务器检索数据，在每个四个线程中有超过15个线程用于从服务器获取图像。那时GC阻止我的四个线程超过1分半...... async方法的所有四个preExecute()任务他们工作得很好......但在doInBackground()它的块为超过1分钟。
先谢谢..........
03-20 19:48:19.250: D/dalvikvm(6416): WAIT_FOR_CONCURRENT_GC blocked 0ms
03-20 19:48:21.020: E/Image(6416): 1
03-20 19:48:21.760: D/dalvikvm(6416): GC_EXPLICIT freed 112K, 8% free 26454K/28551K,
03-20 19:48:23.489: D/dalvikvm(6416): WAIT_FOR_CONCURRENT_GC blocked 0ms
03-20 19:48:26.749: D/dalvikvm(6416): GC_EXPLICIT freed 81K, 7% free 26605K/28551K, paused 66ms+23ms, total 3256ms
03-20 19:48:28.010: E/Image(6416): 2
03-20 19:48:28.470: D/dalvikvm(6416): WAIT_FOR_CONCURRENT_GC blocked 0ms
03-20 19:48:31.220: D/dalvikvm(6416): GC_EXPLICIT freed 76K, 7% free 26762K/28551K, paused 26ms+25ms, total 2751ms
03-20 19:48:32.760: D/dalvikvm(6416): WAIT_FOR_CONCURRENT_GC blocked 0ms
03-20 19:48:35.020: E/Image(6416): 1
03-20 19:48:35.369: D/dalvikvm(6416): GC_EXPLICIT freed 75K, 6% free 26918K/28551K, paused 49ms+44ms, total 2610ms
03-20 19:48:36.950: D/dalvikvm(6416): WAIT_FOR_CONCURRENT_GC blocked 0ms
03-20 19:48:39.690: D/dalvikvm(6416): GC_EXPLICIT freed 77K, 6% free 27074K/28551K, paused 43ms+24ms, total 2660ms
03-20 19:48:41.240: D/dalvikvm(6416): WAIT_FOR_CONCURRENT_GC blocked 0ms
03-20 19:48:42.020: E/Image(6416): 2
03-20 19:48:43.860: D/dalvikvm(6416): GC_EXPLICIT freed 75K, 5% free 27231K/28551K, paused 71ms+48ms, total 2615ms
03-20 19:48:45.740: D/dalvikvm(6416): WAIT_FOR_CONCURRENT_GC blocked 0ms
03-20 19:48:48.641: D/dalvikvm(6416): GC_EXPLICIT freed 76K, 5% free 27388K/28551K, paused 37ms+46ms, total 2901ms
03-20 19:48:49.031: E/Image(6416): 1
03-20 19：48：50.240：D / dalvikvm（6416）：WAIT_FOR_CONCURRENT_GC阻塞了0ms 03-20 19：48：52.950：D / dalvikvm（6416）：GC_EXPLICIT释放77K，4％免费27543K / 28551K，暂停49ms + 44ms，总计2708ms 03-20 19：48：54.550：D / dalvikvm（6416）：WAIT_FOR_CONCURRENT_GC阻塞0ms
下载图片的代码......
public class ImageDownloaderTask扩展了AsyncTask {
private final WeakReference<ImageView> imageViewReference;
private final WeakReference<ProgressBar> progreeBarReferance;
public ImageDownloaderTask(ImageView imageView) {
imageViewReference = new WeakReference<ImageView>(imageView);
progreeBarReferance=null;
}
public ImageDownloaderTask(ImageView imageView, ProgressBar progressBar){
progreeBarReferance= new WeakReference<ProgressBar>(progressBar);
imageViewReference = new WeakReference<ImageView>(imageView);
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
if(progreeBarReferance != null){
ProgressBar progressBar=progreeBarReferance.get();
progressBar.setVisibility(View.VISIBLE);
}
}
@Override
// Actual download method, run in the task thread
protected Bitmap doInBackground(String... params) {
// params comes from the execute() call: params[0] is the url.
return downloadBitmap(params[0]);
}
@Override
// Once the image is downloaded, associates it to the imageView
protected void onPostExecute(Bitmap bitmap) {
if (isCancelled()) {
bitmap = null;
}
if(progreeBarReferance != null){
ProgressBar progressBar=progreeBarReferance.get();
if(progressBar != null){
progressBar.setVisibility(View.GONE);
}
}
if (imageViewReference != null) {
ImageView imageView = imageViewReference.get();
if (imageView != null) {
if (bitmap != null) {
imageView.setImageBitmap(bitmap);
} else {
imageView.setImageDrawable(imageView.getContext().getResources()
.getDrawable(R.drawable.ic_launcher));
}
}
}
}
static Bitmap downloadBitmap(String url) {
final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
final int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w("ImageDownloader", "Error " + statusCode
+ " while retrieving bitmap from " + url);
return null;
}
final HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream inputStream = null;
try {
inputStream = entity.getContent();
System.gc();
final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
return bitmap;
} finally {
if (inputStream != null) {
inputStream.close();
}
entity.consumeContent();
}
}
}catch (Exception e) {
// Could provide a more explicit error message for IOException or
// IllegalStateException
getRequest.abort();
Log.w("ImageDownloader", "Error while retrieving bitmap from " + url);
} catch(Throwable e){
Log.e("From Throwable", "");
e.printStackTrace();
}finally {
if (client != null) {
client.close();
}
}
return null;
}
}
在One Fragment上有四个列表视图。每个listview处理单独的asynctask个列表项ImageDownloaderASynctask
在列表视图项上设置图像的代码
以下代码对于所有四个listview适配器
@Override
public View getView(int position, View convertView, ViewGroup arg2) {
// TODO Auto-generated method stub
if (convertView == null) {
LayoutInflater mInflater = (LayoutInflater)
context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
convertView = mInflater.inflate(R.layout.my_swaps_item, null);
}
ImageView imgIcon = (ImageView)convertView.findViewById(R.id.my_swap_item_ImageView_image);
TextView title=(TextView)convertView.findViewById(R.id.my_swaps_item_textview_title);
ProgressBar progressBar=(ProgressBar)convertView.findViewById(R.id.my_swaps_item_progressBar);
title.setText(followersList.get(position).first_name);
new ImageDownloaderTask(imgIcon,progressBar).execute(followersList.get(position).imageUrl);
return convertView;
async任务，用于从服务器获取单个片段上的四个列表视图
public class GetProfileDataAsyncTask extends AsyncTask<Void, Void, Void>{
private String[] ids;
private String[] params;
private JMYSwapsList jmySwapList;
private int flag;
private JMyFriendsList jmyFriendsList;
private JMyFollowerList jMyFollowerList;
private JProfileList jProfileList;
public GetProfileDataAsyncTask(String[] ids, String[] params, int flag) {
// TODO Auto-generated constructor stub
this.ids=ids;
this.params=params;
this.flag=flag;
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
Log.e("0", "1");
if(flag==0)
{
mySwapProgressBar.setVisibility(View.VISIBLE);
}
if(flag==1){
myFriendProgressBar.setVisibility(View.VISIBLE);
}
if(flag == 2){
myFollowersProgressBar.setVisibility(View.VISIBLE);
}
if(flag == 3){
friendRequestProgressBar.setVisibility(View.VISIBLE);
}
Log.e("0", "2");
// System.gc();
}
@Override
protected Void doInBackground(Void... arg0) {
// TODO Auto-generated method stub
Log.e("1", "1");
if(flag == 0){
String response= Profiles.getDataFromServer(ids, params, Constants.My_SWAP_URL);
Log.e("2", "1");
jmySwapList=Profiles.parseMySwap(response);
if(jmySwapList != null){
if(jmySwapList.Success != null){
for (JSwap jSwap: jmySwapList.Success) {
System.out.println("from do Person "+ jSwap.name);
mySwapList.add(new MySwapsData(jSwap.name,"http://"+ jSwap.swap_image_thumb.replace("\\","").replace(" ", "%20")));
}
}else{
if(jmySwapList.noData != null){
Log.e("Profile From My Swap", jmySwapList.noData);
}
}
}
}
Log.e("1", "2");
if(flag == 1){
String response= Profiles.getDataFromServer(ids, params, Constants.MY_FRIENDS_URL);
Log.e("2", "2");
jmyFriendsList=Profiles.parseMyFriends(response);
if(jmyFriendsList != null){
if(jmyFriendsList.Success != null){
for (JFriend jFriend: jmyFriendsList.Success) {
System.out.println("from do Person "+ jFriend.first_name);
myFrindsList.add(new FriendAdapterData(jFriend.first_name,"http://"+ jFriend.user_image_thumb.replace("\\","").replace(" ", "%20")));
}
}else{
if(jmyFriendsList.noData != null){
Log.e("Profile From My Friends", jmyFriendsList.noData);
}
}
}
}
Log.e("1", "3");
if(flag == 2){
String response= Profiles.getDataFromServer(ids, params, Constants.MY_FOLLOWERS_URL);
Log.e("2", "3");
jMyFollowerList=Profiles.parseMyFollowers(response);
if(jMyFollowerList != null){
if(jMyFollowerList.Success != null){
for (JFollower jFollower: jMyFollowerList.Success) {
System.out.println("from do Person "+ jFollower.user_id);
// myFrindsList.add(new FriendAdapterData(jFollower.user_id,"http://"+ jFriend.user_image_thumb.replace("\\","").replace(" ", "%20")));
myFollowerList.add(new FollowerAdapterData(jFollower.first_name,"http://"+ jFollower.user_image_thumb.replace("\\","").replace(" ", "%20")));
}
}else{
if(jMyFollowerList.noData != null){
Log.e("Profile From My Follower", jMyFollowerList.noData);
}
}
}
}
Log.e("1", "4");
if(flag == 3){
}
if(flag == 4){
String response= Profiles.getDataFromServer(ids, params, Constants.GET_PROFILE);
jProfileList=Profiles.parseProfile(response);
if(jProfileList != null){
if(jProfileList.Success != null){
for(JProfile jProfile: jProfileList.Success){
System.out.println("from do Person "+ jProfile.first_name);
}
}else{
if(jProfileList.noData != null){
Log.e("from Profile", jProfileList.noData);
}
}
}
}
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
//MySwaps
if(flag==0){
mySwapAdapter.notifyDataSetChanged();
mySwapProgressBar.setVisibility(View.INVISIBLE);
}
//Friends
if(flag==1){
myFriendAdapter.notifyDataSetChanged();
myFriendProgressBar.setVisibility(View.INVISIBLE);
}
//Follower
if(flag == 2){
myFollowerAdapter.notifyDataSetChanged();
myFollowersProgressBar.setVisibility(View.INVISIBLE);
}
//Friend Rquest
if(flag == 3){
friendRequestProgressBar.setVisibility(View.INVISIBLE);
}
if(flag == 4){
String imageUrl=null;
if(jProfileList != null){
for(JProfile jProfile: jProfileList.Success){
//System.out.println("from do Person "+ jProfile.first_name);
// imageUrl=jProfile.user_image_thumb;
imageUrl="http://"+ jProfile.user_image_thumb.replace("\\","").replace(" ", "%20");
}
}
if(imageUrl != null)
{
new ImageDownloaderTask(myProfileImage).execute(imageUrl);
}
}
}
}
答案 0 :(得分：0)
尝试更改该行：
new ImageDownloaderTask(myProfileImage).execute(imageUrl);
到：
new ImageDownloaderTask(myProfileImage).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, imageUrl);
它允许您的任务在不同的线程上运行。
第二个问题是：System.gc();
你为什么这么做？在正常情况下（并且下载图像肯定不是火箭信号）垃圾收集器应该只由系统运行，而不是由用户运行。