什么是return语句中的AsyncTask的doInBackg

什么是return语句中的AsyncTask的doInBackg

本文介绍了什么是return语句中的AsyncTask的doInBackground()的目的是什么?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

限时删除!!

我登录系统的这方面工作得很好,如果我有return语句设置为0或1,但如果我使用空失败。这都是改编自其中,这个特殊的回报看起来下面列出我自己的code。

 公共LoginTask(投票活动,ProgressDialog progressDialog)
    {
        this.activity =活动;
        this.progressDialog = progressDialog;
    }保护整数doInBackground(字符串...为arg0){
            userName的的EditText =(EditText上)activity.findViewById(R.id.emailEditText);
            的EditText passwordEdit =(EditText上)activity.findViewById(R.id.passEditText);
            。字符串email = userName.getText()的toString();
            字符串密码= passwordEdit.getText()的toString()。
            UserFunctions userFunction =新UserFunctions();
            JSONObject的JSON = userFunction.loginUser(电子邮件,密码);
            progressDialog.dismiss();
            //检查登录响应
            //Log.v(\"test,Integer.toString(jsonParser.getResponse code()));
            尝试{
                如果(json.getString(KEY_SUCCESS)!= NULL){
                    //loginErrorMsg.setText();
                    //loginFragment.loginErrorMsg.setText(\"Success);
                    字符串资源= json.getString(KEY_SUCCESS);                    如果(的Integer.parseInt(RES)== 1){
                        //用户成功登录
                        在SQLite数据库//存储用户详细信息
                        数据库处理器分贝=新数据库处理器(activity.getApplicationContext());
                        JSONObject的json_user = json.getJSONObject(用户);
                        //Log.v(\"name,json_user.getString(KEY_NAME));
                        //清除数据库中的所有previous数据
                        userFunction.logoutUser(activity.getApplicationContext());
                        db.addUser(json_user.getString(KEY_NAME),json_user.getString(KEY_EMAIL)
                                json.getString(KEY_UID),​​json_user.getString(KEY_CREATED_AT));
                        //关闭登录屏幕
                        //完();
                        // loginErrorMsg =(TextView中)activity.findViewById(R.id.loginErrorMsg);
                        //loginErrorMsg.setText(\"logged在);
                        //passwordEdit.setText();
                    }其他{
                        //错误的登录
                        //progressDialog.setMessage(\"Incorrect用户名或密码);
                        //loginErrorMsg.setText(\"Incorrect用户名/密码);
                    }                }            }赶上(NullPointerException异常五){
                e.printStackTrace();            }
            赶上(JSONException E){
                e.printStackTrace();
            }            返回1;
        }

这是我用过,看看反应code教程:

 保护整数doInBackground(字符串...为arg0)
{
    字符串结果=;
    INT响应code = 0;
    尝试
    {
        HttpClient的客户端=新DefaultHttpClient();
        HttpPost httppost =新HttpPost(http://www.256design.com/projectTransparency/project/headerLogin.php);        清单<&的NameValuePair GT; namevaluepairs中=新的ArrayList<&的NameValuePair GT;();
            nameValuePairs.add(新BasicNameValuePair(EMAILADDRESS,为arg0 [0]));
            nameValuePairs.add(新BasicNameValuePair(密码,将arg0 [1]));
        httppost.setEntity(新UrlEn codedFormEntity(namevaluepairs中));        INT executeCount = 0;
        HTT presponse响应;
        做
        {
            progressDialog.setMessage(登录。(+(executeCount + 1)+/ 5));
            //执行HTTP POST请求
            executeCount ++;
            响应= client.execute(httppost);
            。响应code = response.getStatusLine()的getStatus code();
            //如果你想看到的响应code,就可以登录其
            //在这里致电:
            // Log.d(256设计,状态code:+响应code)
        }而(executeCount小于5&安培;&安培;响应code == 408);        RD的BufferedReader =新的BufferedReader(新的InputStreamReader(
                。response.getEntity()的getContent()));        串线;
        而((行= rd.readLine())!= NULL)
        {
            结果= line.trim();
        }
        ID =的Integer.parseInt(结果);
    }
    赶上(例外五){
        响应code = 408;
        e.printStackTrace();
    }
    返回响应code;
}


解决方案

其目的是通过你的工作结果(这是一个工作线程执行)为 onPostExecute 中,为了处理所述UI线程上的结果。如果你想在响应成功作业运行更新用户界面这是必需的。

This aspect of my login system works just fine if I have the return statement set to 0 or 1, but fails if I use null. This is all adapted from http://256design.com/blog/android-login-asynctask/ where this particular return looks as listed below my own code.

public LoginTask(Polling activity, ProgressDialog progressDialog)
    {
        this.activity = activity;
        this.progressDialog = progressDialog;
    }

protected Integer doInBackground(String... arg0) {
            EditText userName = (EditText)activity.findViewById(R.id.emailEditText);
            EditText passwordEdit = (EditText)activity.findViewById(R.id.passEditText);


            String email = userName.getText().toString();
            String password = passwordEdit.getText().toString();
            UserFunctions userFunction = new UserFunctions();
            JSONObject json = userFunction.loginUser(email, password);
            progressDialog.dismiss();
            // check for login response
            //Log.v("test", Integer.toString(jsonParser.getResponseCode()));
            try {
                if (json.getString(KEY_SUCCESS) != null) {
                    //loginErrorMsg.setText("");
                    //loginFragment.loginErrorMsg.setText("Success");
                    String res = json.getString(KEY_SUCCESS);

                    if(Integer.parseInt(res) == 1){
                        //user successfully logged in
                        // Store user details in SQLite Database
                        DatabaseHandler db = new DatabaseHandler(activity.getApplicationContext());
                        JSONObject json_user = json.getJSONObject("user");
                        //Log.v("name", json_user.getString(KEY_NAME));
                        // Clear all previous data in database
                        userFunction.logoutUser(activity.getApplicationContext());
                        db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL),
                                json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));


                        // Close Login Screen
                        //finish();
                        //loginErrorMsg = (TextView)activity.findViewById(R.id.loginErrorMsg);
                        //loginErrorMsg.setText("logged in");
                        //passwordEdit.setText("");
                    }else{
                        // Error in login
                        //progressDialog.setMessage("Incorrect username or password");
                        //loginErrorMsg.setText("Incorrect username/password");
                    }

                }

            } catch (NullPointerException e) {
                e.printStackTrace();

            }
            catch (JSONException e) {
                e.printStackTrace();
            }

            return 1;
        }

The tutorial that I used, take a look at responseCode:

protected Integer doInBackground(String... arg0)
{
    String result = "";
    int responseCode = 0;
    try
    {
        HttpClient client = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://www.256design.com/projectTransparency/project/headerLogin.php");

        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
            nameValuePairs.add(new BasicNameValuePair("emailAddress", arg0[0]));
            nameValuePairs.add(new BasicNameValuePair("password", arg0[1]));
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

        int executeCount = 0;
        HttpResponse response;
        do
        {
            progressDialog.setMessage("Logging in.. ("+(executeCount+1)+"/5)");
            // Execute HTTP Post Request
            executeCount++;
            response = client.execute(httppost);
            responseCode = response.getStatusLine().getStatusCode();
            // If you want to see the response code, you can Log it
            // out here by calling:
            // Log.d("256 Design", "statusCode: " + responseCode)
        } while (executeCount < 5 && responseCode == 408);

        BufferedReader rd = new BufferedReader(new InputStreamReader(
                response.getEntity().getContent()));

        String line;
        while ((line = rd.readLine()) != null)
        {
            result = line.trim();
        }
        id = Integer.parseInt(result);
    }
    catch (Exception e) {
        responseCode = 408;
        e.printStackTrace();
    }
    return responseCode;
}
解决方案

The purpose is to pass the result of your job (which is executed on a worker thread) to onPostExecute, in order to process the result on the UI thread. This is required if you want to update the user interface in response to a successful job run.

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09-06 17:43