Java Android:NetworkOnMainThreadException异步任务内出现异常错误

好的，我创建了一个内部类，它扩展了AsycTask，以便我的代码能够与UI线程一起运行。然而，我得到了这个错误，所以我假设这意味着我的onPostExecute的某些部分需要在doInBackground中完成，但是我不能确切地知道这是什么

public class asyncTask extends AsyncTask<String, Integer, String> {

        ProgressDialog dialog = new ProgressDialog(PetrolPriceActivity.this);

        @Override
           protected void onPreExecute() {
          dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
          dialog.setProgress(0);
          dialog.setMax(100);
          dialog.setMessage("loading...");
          dialog.show();
           }

         @Override
           protected String doInBackground(String...parmans){
                {

                    for(int i = 0; i < 100; i++){


                        publishProgress(1);
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }

                    }


                    String urlString = petrolPriceURL;
                    String result = "";
                    InputStream anInStream = null;
                    int response = -1;
                    URL url = null;

                    try {
                        url = new URL(urlString);
                    } catch (MalformedURLException e) {
                        // TODO Auto-generated catch block
                        return null;
                    }
                    URLConnection conn = null;
                    try {
                        conn = url.openConnection();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        return null;
                    }

                    // Check that the connection can be opened
                    if (!(conn instanceof HttpURLConnection))
                        try {
                            throw new IOException("Not an HTTP connection");
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            return null;
                        }
                    try
                    {
                        // Open connection
                        HttpURLConnection httpConn = (HttpURLConnection) conn;
                        httpConn.setAllowUserInteraction(false);
                        httpConn.setInstanceFollowRedirects(true);
                        httpConn.setRequestMethod("GET");
                        httpConn.connect();
                        response = httpConn.getResponseCode();
                        // Check that connection is OK
                        if (response == HttpURLConnection.HTTP_OK)
                        {
                            // Connection is OK so open a reader 
                            anInStream = httpConn.getInputStream();
                            InputStreamReader in= new InputStreamReader(anInStream);
                            BufferedReader bin= new BufferedReader(in);

                            // Read in the data from the RSS stream
                            String line = new String();
                            while (( (line = bin.readLine())) != null)
                            {
                                result = result + "\n" + line;
                            }
                        }
                    }
                    catch (IOException ex)
                    {
                            try {
                                throw new IOException("Error connecting");
                            } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }
                    }

            return result;

                }
           }
           @Override

           protected void onProgressUpdate(Integer...progress){

               dialog.incrementProgressBy(progress[0]);
           }

           @Override
           protected void onPostExecute(String result) {
               // Get the data from the RSS stream as a string

               errorText = (TextView)findViewById(R.id.error);
               response = (TextView)findViewById(R.id.title);

               try
                {
                    // Get the data from the RSS stream as a string
                    result =  doInBackground(petrolPriceURL);
                    response.setText(result);
                    Log.v(TAG, "index=" + result);
                }
                catch(Exception ae)
                {
                    // Handle error
                    errorText.setText("Error");
                    // Add error info to log for diagnostics
                    errorText.setText(ae.toString());
                } 
                if(dialog.getProgress() == dialog.getMax())
                dialog.dismiss();

           }
        }

如果有人能指出我的错误，并在我的doInBackground中展示代码应该放在哪里的示例，那就太好了。谢谢，问题：

您正在onPostExecute中隐式调用doInbackground方法，该方法实际上将在您的UI线程中运行，而不是在另一个线程上运行，从而导致Android:NetworkOnMainThreadException

另外，当您执行异步任务时，在onPostExecute之前已经执行了doInBackground，不必调用它。只需直接使用onPostExecute的结果参数

样本：

---

我怀疑错误与代码的这一部分有关：

try
 {
 // Get the data from the RSS stream as a string
 result =  doInBackground(petrolPriceURL);
 response.setText(result);
 Log.v(TAG, "index=" + result);
 }

当您调用asynctask.execute时，会自动调用doInBackgound。要正确启动任务，您应该1创建任务的新实例；2在execute方法中传递doInBackground中需要使用的字符串参数；3使用它们；4将结果返回到onPostExecute

例如：

 //in your activity or fragment
 MyTask postTask = new MyTask();
 postTask.execute(value1, value2, value3);

 //in your async task
 @Override
 protected String doInBackground(String... params){

      //extract values
      String value1 = params[0];
      String value2 = params[1];
      String value3 = params[2];

      // do some work and return result
      return value1 + value2;
 }

 @Override
 protected void onPostExecute(String result){

      //use the result you returned from you doInBackground method
 }

---

您应该尝试使用doInBackground方法完成所有工作。Reutrn要在主/UI线程上使用的结果。这将自动作为参数传递给在主/UI线程上运行的onPostExecute方法。

非常感谢我是AsycTask新手，但我应该意识到这个错误。这已经奏效了，非常感谢您提供的代码示例非常好的答案，但是我实际上返回了值。这是一个愚蠢的错误，我在onPostExecute中再次访问doInBackground方法，这完全没有用，因为在执行asyncTask时调用了该方法。我明白我的错误，但非常感谢你的回答

try
 {
 // Get the data from the RSS stream as a string
 result =  doInBackground(petrolPriceURL);
 response.setText(result);
 Log.v(TAG, "index=" + result);
 }

 //in your activity or fragment
 MyTask postTask = new MyTask();
 postTask.execute(value1, value2, value3);

 //in your async task
 @Override
 protected String doInBackground(String... params){

      //extract values
      String value1 = params[0];
      String value2 = params[1];
      String value3 = params[2];

      // do some work and return result
      return value1 + value2;
 }

 @Override
 protected void onPostExecute(String result){

      //use the result you returned from you doInBackground method
 }