ProgressDialog不AsyncTask的示 [英] ProgressDialog not shown in AsyncTask

问题描述

我在一个SD卡一个庞大的数据库（40MB）。我需要获取数据，以 LIKE 查询，这是非常慢的。

I have a huge database (40MB) on an SDCard. I need fetch data, with LIKE in query, which is very slow.

DB请求大约需要5秒钟。因此，我需要异步做到这一点，与 ProgressDialog 。

DB request takes about 5 seconds. Therefore, I need to do it asynchronously and with ProgressDialog.

我用的AsyncTask 尝试过，但问题是与 ProgressDialog
它是这样实现：

I tried it with AsyncTask, but problem is with ProgressDialog.
It was implemented this way:

private class GetDataFromLangDB extends AsyncTask<String, String, String> {

    private final ProgressDialog dialog = new ProgressDialog(TranslAndActivity.this);

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

         urDBCursor.close();
         curDBCursor = null;
         scaAdapter = null;

         this.dialog.setMessage("Loading data...");
         this.dialog.show();

    } 

    @Override
    protected String doInBackground(String... whatSearch) {
        String result = "";

        if (myDatabaseAdapter != null) {
            curDBCursor = myDatabaseAdapter.fetchAll(whatSearch[0]);
        }
        return result;
    }

    @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);

            if (this.dialog.isShowing()) {
                this.dialog.dismiss();
            }

            prepareListView();
    }
}

问题是， ProgressDialog 未在DB请求过程中。
成品数据库查询后，将其在屏幕上闪烁的时间很短。当用户试图
挖掘数据库请求期间的屏幕，UI被冻结，并DB请求后
显示关于没有响应的消息。


我用一个线程尝试这种方式：

The problem is that ProgressDialog is not shown during the DB request. After finished database query, it flash on screen for a short time. When user tries to tap on screen during database request, UI is freezed, and after DB request message about 'not responding' is shown.

I tried it with a thread this way:

public void startProgress(View view, final String aWhatSearch) {

        final ProgressDialog dialog = new ProgressDialog(MyActivity.this);
        if (curDBCursor != null){
            curDBCursor.close();
            curDBCursor = null;
        }

        dialog.setMessage("Loading data...");
        dialog.show();
        Runnable runnable = new Runnable() {
            public void run() {
                curDBCursor = myDatabaseAdapter.fetchAll(aWhatSearch);
                // dirty trick
                try {
                    Thread.sleep(250); // it must be here to show progress
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                handler.post(new Runnable() {
                    public void run() {
                        if (dialog.isShowing()) {
                            dialog.dismiss();
                        }
                        prepareListView();
                    }
                });

            }
        };
        new Thread(runnable).start();
    }

的结果是一样的，但是当我用的伎俩与视频下载（250）;
  ProgressDialog 是在数据库请求过程中显示。但它不旋转，
 它的外观DB请求期间冻结。

The result was the same, but when I used the trick with Thread.sleep(250); ProgressDialog was shown during the database request. But it is not spinning, it looks freezed during the DB request.

DB的东西被称为这样（在搜索按钮自来水后）：

DB stuff is called this way (after tap on search button):

btnSearchAll.setOnClickListener(new OnClickListener() {
    public void onClick(View v) {
        // AsyncTask
        new GetDataFromLangDB().execute(edtTextToSearch.getText().toString());

        // or Thread 
        //startProgress(null, edtTextToSearch.getText().toString());
    }
});

我发现了很多这样的问题，在SO，但没有什么是有用的我。
 难道说DB是SD卡？

I found a lot of problems like this in SO, but nothing was useful for me. Could it be that DB is on SD Card?

推荐答案

我把对话框进入的AsyncTask类的定义，它为我工作得很好。
看看这个exampel（你必须改变NAMEOFCLASS在你的类的名称：

I put the definition of the dialog into the AsyncTask Class and it works fine for me. Take a look at this exampel (You have to change NAMEOFCLASS in the name of your CLASS:

private class doInBackground extends AsyncTask<Integer, Integer, Void> {

   final ProgressDialog dialog = new ProgressDialog(NAMEOFCLASS.this) {

    @Override
    protected void onPreExecute() {
        dialog.setCancelable(false);
        dialog.setTitle(getString(R.string.daten_wait_titel));
        dialog.setIcon(R.drawable.icon);
        dialog.setMessage(getString(R.string.dse_dialog_speichern));
        dialog.show();
    }

    @Override
    protected void onCancelled() {
        dialog.cancel();
    }

...

    @Override
    protected void onProgressUpdate(Integer... values) {
                   // DO YOUR UPDATE HERE
    }

    @Override
    protected void onPostExecute(Void result) {
        dialog.dismiss();
                }

}

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