java.io.IOException：流已关闭-AndroidStudio

Question

嘿，我正在使用android studio和Postgresql，如果有人可以帮助我，将不胜感激。

 public class getlistAsynctask extends AsyncTask<String,String,String>{

        @Override
        protected String doInBackground(String... params) {
            String data="";
            String username="admin";
            String password="admin";
            URL url =null;
            HttpURLConnection urlConnection =null;
            publishProgress("doInBackground");
            try {
                url=  new URL(params[0]);
                urlConnection = (HttpURLConnection) url.openConnection();


                InputStream in = new BufferedInputStream(urlConnection.getInputStream());
                data= Stream2String(in);
                InputStreamReader isw = new InputStreamReader(in);

                int datax = isw.read();
                while (datax != -1) {
                    char current = (char) datax;
                    datax = isw.read();
                    System.out.print(current);
                }
                publishProgress(data);


            }catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (urlConnection != null) {
                    urlConnection.disconnect();
                }
            }
            //textView.setText(data);
            return data;
        }

在这里，这似乎是正确的，但是我没有从数据库中获取任何信息。我得到一个空白页。

W/System.err: java.io.IOException: Stream closed
W/System.err:     at java.io.BufferedInputStream.getBufIfOpen(BufferedInputStream.java:162)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:325)
        at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:287)
        at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:350)
        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:179)
W/System.err:     at sun.nio.cs.StreamDecoder.read0(StreamDecoder.java:128)
        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:114)
        at java.io.InputStreamReader.read(InputStreamReader.java:168)
        at org.hsbo.gierthhensen.coolesachenmitleaflet.List_laureat_Activity$getlistAsynctask.doInBackground(List_laureat_Activity.java:185)
        at org.hsbo.gierthhensen.coolesachenmitleaflet.List_laureat_Activity$getlistAsynctask.doInBackground(List_laureat_Activity.java:158)
        at android.os.AsyncTask$2.call(AsyncTask.java:304)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
        at java.lang.Thread.run(Thread.java:761)
W/art: Attempt to remove non-JNI local reference, dumping thread

我的数据库与Postman完美配合，我使用相同的URL即可获得所需的响应，但在应用程序中却无法。