Question

我有与mysql数据库交互并下载数据和图片的代码。因此，当我运行此代码时，下载数据需要一些时间，我的手机屏幕会冻结片刻，有时会变黑。我在此代码之前放了一个ProgressDialog，但它在下载数据后出现。现在我使用AsyncTask类，但它仍然没有显示ProgressDialog

我打电话给这个班：

myarray = new Download(getApplicationContext()).doInBackground("my php file URL");

这是班级：

class Download extends AsyncTask<String, String, MyArray>
{

ProgressDialog progressdialog;
Context baseconext;


public Download(Context baseconext)
{
    this.baseconext = baseconext;
}

@Override
protected MyArray doInBackground(String... params) {
    // TODO Auto-generated method stub

    MyArray myarray = new MyArray();
    myarray = getdata("http://www.neginmelk.ir/app/getnews.php");
    myarray = getpic(myarray);
    return myarray;
}

@Override
protected void onPostExecute(MyArray result) {
    // TODO Auto-generated method stub
    progressdialog = ProgressDialog.show(baseconext, "dialog title",
              "dialog message", true);

}

@Override
protected void onPreExecute() {
    // TODO Auto-generated method stub
    progressdialog.dismiss();
}

@Override
protected void onProgressUpdate(String... values) {
    // TODO Auto-generated method stub
    super.onProgressUpdate(values);
}
public MyArray getpic(MyArray temparray)
{
    System.out.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
    for (int i = 0; i < temparray.arrpath.length; i++) 
    {
        System.out.println(temparray.arrpath[i]);
    }
    for (int i = 0; i < temparray.arrpath.length; i++) 
    {
        if(!temparray.arrpath[i].equalsIgnoreCase("null"))
        {
            try {
                    URL url = new URL(temparray.arrpath[i].toString());
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setDoInput(true);
                    connection.connect();
                    InputStream input = connection.getInputStream();
                    Bitmap bitmap = BitmapFactory.decodeStream(input);
                    temparray.arrpic.add(bitmap);



            } catch (Exception e) {
                // TODO: handle exception
                //Toast.makeText(getApplicationContext(), "error ocures", Toast.LENGTH_LONG).show();

            }
        }
        else
        {
            temparray.arrpic.add(null);
        }
    }
    return temparray;


}
public MyArray getdata(String src)
{
    InputStream is = null;
    String line,result = null;
    MyArray myarray = new MyArray();

        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);

        try {
            HttpClient httpClient= new DefaultHttpClient();
            HttpPost httpPost=new HttpPost(src);
           // httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response =httpClient.execute(httpPost);
            HttpEntity entity= response.getEntity();

            is=entity.getContent();

        } catch (ClientProtocolException e) {
            //Toast.makeText(this,"exeption client", Toast.LENGTH_LONG).show();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            //Toast.makeText(this,"exeption io", Toast.LENGTH_LONG).show();
        }
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"),8);
            StringBuilder sb = new StringBuilder();
            while((line = reader.readLine())!=null)
                sb.append(line + "\n");

            result = sb.toString();
            is.close();
            System.out.println("********************************************my************");
            System.out.println(result);
            //Toast.makeText(this,"asdasdadsadsads", Toast.LENGTH_LONG).show();





        } catch (Exception e) {
            //Toast.makeText(Description.this,"exeption 2", Toast.LENGTH_LONG).show();
        }
        //////////////////json to array
        try {

            String title = "",content="",imgpath = "";


            JSONArray jArray = new JSONArray(result);
            int count = jArray.length();

            for (int i = 0; i <count; i++) 
            {
                JSONObject json_data = jArray.getJSONObject(i);
                title += json_data.getString("title")+ ":";
                content += json_data.getString("content")+ ":";
                imgpath += json_data.getString("imgpath")+ "#";

            }
            System.out.println("<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<,return from get data");
            System.out.println(imgpath);
            myarray.arrtitle = title.split(":");
            myarray.arrcontent = content.split(":");
            myarray.arrpath = imgpath.split("#");

                System.out.println("///////////////////////////////////////////////////data");
                System.out.println(myarray.arrpath);


        } catch (Exception e) {
            //Toast.makeText(this,"exeption last", Toast.LENGTH_LONG).show();
        }
        //Toast.makeText(Description.this, "we r returning", Toast.LENGTH_LONG).show();

        return myarray;


}


}

Answer 1

在调用asynctask之前在java文件中显示progressdialog：

pDialog = ProgressDialog.show(YourActivityName.this,"","Creating New Card...", true);
pDialog.setCancelable(true);

然后在你的ASyncTask中，在onPostExecute中解除它。

@Override
protected void onPostExecute(MyArray result) {
    // TODO Auto-generated method stub
       pDialog.dismiss();
}

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

Answer 2

像这样使用：

 @Override
protected void onPreExecute() {
    // TODO Auto-generated method stub
    progressdialog = ProgressDialog.show(baseconext, "dialog title",
              "dialog message", true);
}

并在后期执行：

  @Override
protected void onPostExecute(MyArray result) {
    progressdialog.dismiss();

}

Answer 3

Sajjad，您需要在活动中定义进度对话框。

 private ProgressDialog prgDialog;

然后在AsycTask中，你需要写下面的代码：

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

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

        prgDialog = new ProgressDialog(YourActivityName.this);
        prgDialog.setMessage("Downloading Data. Please wait...");
        prgDialog.setIndeterminate(false);
        prgDialog.setMax(100);
        prgDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        prgDialog.setCancelable(false); //depends on you
        prgDialog.show();
    }

    @Override
    protected Void doInBackground(Void... arg0) {

        InputStream input = null;
        OutputStream output = null;
        HttpURLConnection connection = null;
        try {
            URL url = new URL(Constant.jsonCall);

            connection = (HttpURLConnection) url.openConnection();

            connection.setConnectTimeout(5000);
            connection.connect();

            // expect HTTP 200 OK, so we don't mistakenly save error report
            // instead of the file
            if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                //       return Error           
            }

            int fileLength = connection.getContentLength();


            input = connection.getInputStream();

            byte data[] = new byte[4096];
            long total = 0;
            int count;
            while ((count = input.read(data)) != -1) {

                total += count;
                if (fileLength > 0){
                    publishProgress((int) (total * 100 / fileLength));
                }

            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (output != null)
                    output.close();
                if (input != null)
                    input.close();
            } catch (IOException ignored) {
            }

            if (connection != null)
                connection.disconnect();
        }
        return null;
    }


    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
      //do your work
    }

    //Update the progress
    @Override
    protected void onProgressUpdate(Integer... values)
    {
        prgDialog.setProgress(values[0]);
    }

}

ProgressDialog不会出现

3 个答案: