AsyncTask doInBackground和postExecute

Question

我有php脚本将json返回给android。成功消息没问题。但是我将如何处理表单验证错误消息，如“用户名已存在”，“无效的学生ID”等，通过android在json_encode内部。我尝试将数据类型更改为JSONObject，但它给了我很多红线错误。

任何建议或某事谢谢你们。

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

    int success;

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub

    }

    @Override
    protected String doInBackground(String... arg0) {
        // TODO Auto-generated method stub
        try {
            String studId = studentId.getText().toString();
            String uName = username.getText().toString();
            String pWord = password.getText().toString();
            String cPWord = cfmPassword.getText().toString();


            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("studNum", studId));
            params.add(new BasicNameValuePair("username", uName));
            params.add(new BasicNameValuePair("password", pWord));
            params.add(new BasicNameValuePair("cfmPassword", cPWord)

            JSONParser parser = new JSONParser(); my Class in other activity
            JSONObject json = parser.requestHttp(REG_URL, "POST", params);

            success = json.getInt(TAG_SUC);//get success msg

            if(success == 1){ //No problem here
                return json.getString(TAG_MSG);
            }else{
                //If there's invalid input php script return here
                return json; //Problem returning json to PostExecute
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        //User JSONObject here to activity
    }

}

Answer 1

尝试类似这样的事情

public class httpRegister extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... arg0) {
        // TODO Auto-generated method stub
        try {
            String studId = studentId.getText().toString();
            String uName = username.getText().toString();
            String pWord = password.getText().toString();
            String cPWord = cfmPassword.getText().toString();


            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("studNum", studId));
            params.add(new BasicNameValuePair("username", uName));
            params.add(new BasicNameValuePair("password", pWord));
            params.add(new BasicNameValuePair("cfmPassword", cPWord)

            JSONParser parser = new JSONParser(); my Class in other activity
            JSONObject json = parser.requestHttp(REG_URL, "POST", params);

           return json.toString();


        } catch (Exception e) {
            e.printStackTrace();
        }
        return "Error";
    }

    @Override
    protected void onPostExecute(String result) {
         if(result.equals("Error")){
            //SHOW ERROR MSG
        }else{
            //doSomething
        }
    }

}

Answer 2

您可以这样做：

 public class httpRegister extends AsyncTask<String, Void, String> {
            @Override
            protected String doInBackground(String... arg0) {
                // TODO Auto-generated method stub

                try {
                    String studId = studentId.getText().toString();
                    String uName = username.getText().toString();
                    String pWord = password.getText().toString();
                    String cPWord = cfmPassword.getText().toString();
                    List<NameValuePair> params = new ArrayList<NameValuePair>();
                    params.add(new BasicNameValuePair("studNum", studId));
                    params.add(new BasicNameValuePair("username", uName));
                    params.add(new BasicNameValuePair("password", pWord));
                    params.add(new BasicNameValuePair("cfmPassword", cPWord));
                    JSONParser parser = new JSONParser();

                    // my Class in other activity

                    JSONObject json = parser.requestHttp(REG_URL, "POST", params);
                    return "Success";
                } catch (Exception e) {
                    e.printStackTrace();
                }
                return "Error";
            }

            @Override
            protected void onPostExecute(String result) {
                if (result.equals("Success")) {
                    // DO SOMETHING
                } else if (result.equals("Error")) {
                    // SHOW ERROR MSG
                }
                if (result.equals("Username_Exists")) {
                    // show toast
                }
            }
        }

Answer 3

要返回JSONObject，请尝试以下操作：

public class httpRegister extends AsyncTask <String, Void, JSONObject> {

    int success;

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub

    }

    @Override
    protected JSONObject doInBackground(String... arg0) {
        // TODO Auto-generated method stub
        try {
            String studId = studentId.getText().toString();
            String uName = username.getText().toString();
            String pWord = password.getText().toString();
            String cPWord = cfmPassword.getText().toString();


            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("studNum", studId));
            params.add(new BasicNameValuePair("username", uName));
            params.add(new BasicNameValuePair("password", pWord));
            params.add(new BasicNameValuePair("cfmPassword", cPWord)

            JSONParser parser = new JSONParser(); my Class in other activity
            JSONObject json = parser.requestHttp(REG_URL, "POST", params);

           return json;

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub

        if(result!=null){
           // Get Data from JSONResponce here
         }

          success = json.getInt(TAG_SUC);//get success msg
        //User JSONObject here to activity
    }

}

Answer 4

问题解决了，非常感谢你对我的问题的快速建议我在这里提出问题。我虽然stackoverflow是不活跃的网站因此。当我看到帖子的日期时，评论似乎是3到5年前我在这里搜索。哈哈无论如何。

首先，我喜欢这样做

AsyncTask <String, Integer, String>{ 
}
protected String doInBackground(String... arg0){
}
protected void onPostExecute(String result){
}

然后将其更改为

AsyncTask<JSONObject, Object, JSONObject> //But I don't know why here haha
protected JSONObject doInBackground(JSONObject... arg0)// And the dot dot dot{

  //here is 
  return json;
}

protected void onPostExecute(JSONObject result){
 //here I use json
 int success2;
        try {
            success2 = result.getInt(TAG_SUC);
            if(success2 == 1){
                //get success msg
            }else{
                //get msg's of form validation
            }
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
  }

有任何改进的想法吗？ ^ ___ ^ thx to all。