我在活动中有一个 ListView。列表元素是从 BaseAdapter 生成的。随着用户在屏幕上向下滚动，该列表不断增长。实际上，AsyncTask 负责从 Internet 下载数据并为 ListView 生成 View 元素。
每个 View 元素都有一组 onClickListener。OnClickListener 类开始一个新的活动......
问题是有时 GUI 对点击动作没有反应。例如 1. 启动应用程序 2. 点击第一个元素 -> 没有任何反应 3. 点击第二个元素 -> 没有任何反应 4. 向下滚动 a 但是 -> 两个相应的活动都出现（彼此）
列表适配器：
private class HirdetesListaAdapter extends BaseAdapter {
private GSResult hirdetesek;
private final Context context;
private LayoutInflater inflater = null;
private SparseArray<ImageDownloaderThread> imageDownloadThreads;
private ListViewWorker worker;
private int thresHold = 45;
private ArrayList<View> views;
private boolean isWorkerThreadRunning = false;
public HirdetesListaAdapter(final Context context, GSResult result) throws IOException {
this.context = context;
inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
initAdapter(result);
}
public void initAdapter(GSResult result) {
if (views == null) {
views = new ArrayList<View>();
} else {
views.clear();
}
hirdetesek = result;
imageDownloadThreads = new SparseArray<ImageDownloaderThread>();
worker = new ListViewWorker();
worker.execute(null, null, null);
}
@Override
public int getCount() {
// Log.v("bar2", "HirdetesListaAdapter.getCount()=" + views.size());
return views.size();
}
@Override
public GSHirdetes getItem(int arg0) {
Log.v("bar", "HirdetesListaAdapter.getItem(" + arg0 + ")");
// Toast.makeText(getBaseContext(), "Találatok: " + gsr.size(),
// 100000).show();
return hirdetesek.get(arg0);
}
public void destroy() {
synchronized (worker) {
worker.notify();
Log.v("thread", "Working thread notified");
worker.cancel(true);
Log.v("thread", "Working thread cancelled");
for (int i = 0; i < this.imageDownloadThreads.size(); i++) {
imageDownloadThreads.get(i).cancel(false);
Log.v("thread", "ImageDownloadThread " + i + " cancelled");
}
}
}
@Override
public long getItemId(int arg0) {
Log.v("bar", "HirdetesListaAdapter.getItemId(" + arg0 + ")");
return arg0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if ((lv.getLastVisiblePosition() + thresHold) > views.size()) {
synchronized (worker) {
if (!this.isWorkerThreadRunning) {
Log.v("wthread", "Resuming worker thread");
worker.notify();
isWorkerThreadRunning = true;
}
}
}
synchronized (imageDownloadThreads) {
if (imageDownloadThreads.get(position) == null) {
Log.v("ithread", "Storing download thread: " + position);
ImageDownloaderThread thread = new ImageDownloaderThread();
imageDownloadThreads.put(position, thread);
thread.execute(position);
}
}
Log.v("thread", "getview finished for " + position);
return views.get(position);
}
private class ListViewWorker extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... arg0) {
Log.v("thread", "ListViewWorker started");
int buffer = 20;
int i = 0;
try {
while ((views.size() != gsr.size()) && !this.isCancelled()) {
Log.v("thread", views.size() + "/" + gsr.size());
if (buffer != 0) {
views.add(i, makeView(i));
ResultActivity.this.runOnUiThread(new Runnable() {
public void run() {
lv.addFooterView(views.get(views.size() - 1));
}
});
i++;
buffer--;
} else {
synchronized (this) {
try {
Log.v("wthread", "Pausing worker thread");
buffer = 20;
this.wait();
HirdetesListaAdapter.this.isWorkerThreadRunning = false;
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
private View makeView(int position) {
Log.v("thread", "ListViewWorker.makeView(" + position + ")");
GSHirdetes hirdetes = hirdetesek.get(position);
View hirdetesView = inflater.inflate(R.layout.hirdetes_listaelem, null);
TextView hirdetesName = (TextView) hirdetesView.findViewById(R.id.hirdetesListaElemView_TextView_Name);
TextView hirdetesAr = (TextView) hirdetesView.findViewById(R.id.hirdetesListaElemView_TextView_Ar);
TextView hirdetesKategoria = (TextView) hirdetesView.findViewById(R.id.hirdetesListaElemView_TextView_Kategoria);
hirdetesName.setText(position + ". " + hirdetes.getHirdetesName());
// hirdetesName.setText(Integer.toString(position));
hirdetesAr.setText(hirdetes.getHirdetesPrice());
hirdetesKategoria.setText(hirdetes.getCategory());
ImageView hirdetesImage = (ImageView) hirdetesView.findViewById(R.id.hirdetesListaElemView_ImageView_HirdetesCover);
//hirdetesImage.setOnClickListener(new HirdetesImageListener(context, hirdetes));
//hirdetesView.setOnClickListener(new HirdetesListaListener(context, hirdetes));
//views.add(position, hirdetesView);
Log.v("gui", "ListViewWorker.makeView(" + position + ") finished");
return hirdetesView;
}
}
private class ImageDownloaderThread extends AsyncTask<Integer, Integer, Bitmap> {
private ProgressBar progressBar;
private TextView percent;
private URL imageUrl;
private View view;
private int sorszám = -1;
public void onPreExecute() {
super.onPreExecute();
// while (threadCounter >= threadPool) {
// try {
// Log.v("konti","threadCounter:"+threadCounter+" threadPool:"+threadPool);
// Thread.sleep(10);
// } catch (InterruptedException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// }
//
// }
//
// threadCounter++;
}
public void onProgressUpdate(Integer... values) {
progressBar.setProgress(values[0]);
float percentValue = (float) progressBar.getProgress() / progressBar.getMax();
DecimalFormat df = new DecimalFormat("#");
String percentString = df.format(percentValue * 100) + "%";
percent.setText(percentString);
// Log.v("konti", percentString);
}
@Override
protected Bitmap doInBackground(Integer... params) {
sorszám = params[0];
imageUrl = hirdetesek.get(sorszám).gethirdetesCoverImageUrl();
view = views.get(sorszám);
progressBar = (ProgressBar) view.findViewById(R.id.hirdetesListaElemView_ProgressBar_ImageDLProgressBar);
progressBar.setIndeterminate(false);
progressBar.setProgress(0);
percent = (TextView) view.findViewById(R.id.hirdetesListaElemView_TextView_ImageDLPercent);
if (imageUrl == null) {
return null;
}
Log.v("thread", "Starting ImageDownloaderThread for " + sorszám);
int size;
try {
size = imageUrl.openConnection().getContentLength();
progressBar.setMax(size);
InputStream is = imageUrl.openStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[2048];
int read = 0;
Log.v("gui", "Downloading image for " + sorszám + ": " + imageUrl.getPath());
while ((read = is.read(buffer, 0, buffer.length)) != -1) {
baos.write(buffer, 0, read);
// Log.v("net", "Image download progress: " +
// baos.size());
publishProgress(progressBar.getProgress() + read);
}
baos.flush();
byte[] data = baos.toByteArray();
return BitmapFactory.decodeByteArray(data, 0, data.length);
} catch (IOException e) {
Log.v("exception", "thread");
return null;
}
}
protected void onPostExecute(Bitmap bitmap) {
ResultActivity.this.runOnUiThread(new Runnable() {
public void run() {
ViewGroup vg = (ViewGroup) (progressBar.getParent());
vg.removeView(progressBar);
vg.removeView(percent);
}
});
ImageView im = (ImageView) view.findViewById(R.id.hirdetesListaElemView_ImageView_HirdetesCover);
if (bitmap == null) {
im.setImageResource(R.drawable.noimage_hu);
} else {
im.setImageBitmap(bitmap);
}
}
}
}
听众：
public class HirdetesListaListener implements View.OnClickListener {
GSHirdetes hirdetes;
Context context;
public HirdetesListaListener(Context context, GSHirdetes hirdetes){
this.hirdetes = hirdetes;
this.context = context;
Log.v("konti","Listener: "+hirdetes.getHirdetesName());
}
@Override
public void onClick(View v) {
Log.v("konti","HirdetesListaListener.onClick(v) "+hirdetes.getHirdetesName());
Intent intent = new Intent(context, HirdetesActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.putExtra("data", hirdetes);
context.startActivity(intent);
}
}