Question

我在AsyncTask中调用了2个Web服务方法。第一个被成功调用但第二个Web服务方法未被调用。知道如何在第一个方法之后调用第二个方法吗？

AsyncTask代码

public class Transaction extends AsyncTask<String,Void,String>
    {
        private String finalBalance1 = "", price1 = "", pName = "", pNric = "", pClass = "", sno = "";
        public Transaction(String price1, String pName, String pNric, String pClass, String sno, String finalBalance1)
        {
            super();
            this.finalBalance1 = Double.toString(finalBalance);
            this.price1 = Double.toString(sPrice);
            this.pName = sRA.studentName;
            this.pNric = sRA.studentNric;
            this.pClass = sRA.studentClass;
            this.sno = logger.stallNo;
        }
        @Override
          protected String doInBackground (String...url)
          { 
            String result = "";

            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://152.226.152.175/NCO/WebService.asmx/InsertStudentTransaction");
            try
            {
                List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(5);
                nameValuePairs.add(new BasicNameValuePair("NRIC", pNric));
                nameValuePairs.add(new BasicNameValuePair("Name", pName));
                nameValuePairs.add(new BasicNameValuePair("Class", pClass));
                nameValuePairs.add(new BasicNameValuePair("StallNo", sno));
                nameValuePairs.add(new BasicNameValuePair("AmountSpent", price1));
                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

                HttpResponse response = httpclient.execute(httppost);
                HttpEntity entity = response.getEntity();
                InputStream in = entity.getContent();
                BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"), 8);
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null)
                {
                    result = line;
                }

             } catch (ClientProtocolException e) {
                 e.printStackTrace();
                } catch (IOException e) {
                 e.printStackTrace();
                }
                return result;
              }

        protected void onPostExecute (String result)
          {
            if(result != null)
            {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://152.226.152.175/NCO/WebService.asmx/UpdateParticulars");
            try
            {
                List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(4);
                nameValuePairs.add(new BasicNameValuePair("NRIC", pNric));
                nameValuePairs.add(new BasicNameValuePair("FixedAmount", finalBalance1));
                nameValuePairs.add(new BasicNameValuePair("Name", pName));
                nameValuePairs.add(new BasicNameValuePair("Class", pClass));
                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                HttpResponse response = httpclient.execute(httppost);
                HttpEntity entity = response.getEntity();
                InputStream in = entity.getContent();
                BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"), 8);
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null)
                {
                    System.out.println(line);
                }


             } catch (ClientProtocolException e) {
                 e.printStackTrace();
             }catch (IOException e) {
                 e.printStackTrace();
             }
            }
          }
    }
}

Answer 1

 @Override is missing before onPostExecute(String result), and check result getting null

Answer 2

创建一个AsyncTask实例，然后最后执行它。并且还缺少覆盖方法。

instance.execute();

并添加

@override before the post execute method.

Answer 3

您需要将@Override添加到onPostExecute方法中，并且您也不能在主线程上使用网络传输。 onPostExecute中的内容需要在另一个AsyncTask中完成。

来自Android Dev Reference：

网络运营可能涉及不可预测的延迟。为了防止这种情况从导致糟糕的用户体验，始终执行网络操作在与UI的单独线程上。 AsyncTask类提供了一个从UI线程启动新任务的最简单方法

Answer 4

@override

protected void onPostExecute（String result）{

Log.i（ “AsynckTask”，结果）;

}

如果您想咨询其他网络服务，您需要其他AsynkTask记住在后台进行的连接而不是UIThread

@override

protected void onPostExecute（String result）{

Log.i（ “AsynckTask”，结果）;

//建立新连接

new AsynkTas（）。execute（）;

}

onPostExecute（）方法未被执行

4 个答案: