java.lang.String 类型的值 <br 无法转换为 JSONObject Android答案

【问题标题】：Value <br of type java.lang.String cannot be converted to JSONObject Androidjava.lang.String 类型的值 <br 无法转换为 JSONObject Android
【发布时间】：2023-03-10 07:13:02
【问题描述】：

我目前正在开发一个 Android 应用程序，每次按下登录按钮时都会出现错误。我知道这个错误有很多实例，但我找不到与我的结构相同的实例。这是我的代码：

LoginActivity.java：

package com.example.sabre8;

import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.example.sabre8.library.DatabaseHandler;
import com.example.sabre8.library.UserFunctions;

public class LoginActivity extends Activity {
    Button btnLogin;
    //Button btnLinkToRegister;
    EditText inputUserID;
    EditText inputPassword;
    TextView loginErrorMsg;

    // JSON Response node names
    private static String KEY_SUCCESS = "success";
    //private static String KEY_ERROR = "error";
    //private static String KEY_ERROR_MSG = "error_msg";
    private static String KEY_UserID = "UserID";
    private static String KEY_PASSWORD = "Password";
    private static String KEY_FNAME = "Fname";
    private static String KEY_MNAME = "Mname";
    private static String KEY_LNAME = "Lname";
    private static String KEY_POSITION= "position";
    private static String KEY_DEPARTMENT = "department";
   // private static String KEY_NAME = "Fname";
    private static String KEY_ADMINTYPE = "admintype";
    private static String KEY_EMAIL = "email";
    private static String KEY_VERIFIER = "verifier";
   // private static String KEY_EMAIL = "email";
   // private static String KEY_CREATED_AT = "created_at";

    private class MyAsyncTask extends AsyncTask<String, Void, JSONObject> {

        protected JSONObject doInBackground(String... params) {
                UserFunctions userFunction = new UserFunctions();
                if (params.length != 2)
                        return null;
                JSONObject json = userFunction.loginUser(params[0], params[1]);
                return json;
        }

        protected void onPostExecute(JSONObject json) {
                try {
            if (json != null && json.getString(KEY_SUCCESS) != null) {
                loginErrorMsg.setText("");
                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(getApplicationContext());
                    JSONObject json_user = json.getJSONObject("userID");

                    // Clear all previous data in database
                    UserFunctions userFunction = new UserFunctions();
                    userFunction.logoutUser(getApplicationContext());
                    //db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                        

                    // Launch Main Screen
                    Intent main = new Intent(getApplicationContext(), MainActivity.class);

                    // Close all views before launching Dashboard
                    main.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(main);

                    // Close Login Screen
                    finish();
                }else{
                    // Error in login
                    loginErrorMsg.setText("Incorrect username/password");
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        }
}

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);

        // Importing all assets like buttons, text fields
        inputUserID = (EditText) findViewById(R.id.loginUserID);
        inputPassword = (EditText) findViewById(R.id.loginPassword);
        btnLogin = (Button) findViewById(R.id.btnLogin);
        loginErrorMsg = (TextView) findViewById(R.id.login_error);

        // Login button Click Event
        btnLogin.setOnClickListener(new View.OnClickListener() {

            public void onClick(View view) {
                String userid = inputUserID.getText().toString();
                String password = inputPassword.getText().toString();                
                new MyAsyncTask().execute(userid, password);
            }

        });

    }
}

DatabaseHandler.java：

    package com.example.sabre8.library;

    import java.util.HashMap;

    import android.content.ContentValues;
    import android.content.Context;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;

    public class DatabaseHandler extends SQLiteOpenHelper {

        // All Static variables
        // Database Version
        private static final int DATABASE_VERSION = 1;

        // Database Name
        private static final String DATABASE_NAME = "adserve";

        // Login table name
        private static final String TABLE_LOGIN = "login";

        // Login Table Columns names
        private static final String KEY_USERID = "userid";
        private static final String KEY_PASSWORD = "password";
        private static final String KEY_FNAME = "fname";
        private static final String KEY_MNAME = "mname";
        private static final String KEY_LNAME = "lname";   
        private static final String KEY_POSITION = "position";
        private static final String KEY_DEPARTMENT = "department";
        private static final String KEY_ADMINTYPE = "admintype";
        private static final String KEY_EMAIL = "email";
        private static final String KEY_VERIFIER = "verifier";

        public DatabaseHandler(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        // Creating Tables
        @Override
        public void onCreate(SQLiteDatabase db) {
            String CREATE_LOGIN_TABLE = "CREATE TABLE " + TABLE_LOGIN + "("
                    + KEY_USERID + " TEXT PRIMARY KEY,"
                    + KEY_PASSWORD + "TEXT,"
                    + KEY_FNAME  + " TEXT,"
                    + KEY_MNAME + "TEXT,"
                    + KEY_LNAME + "TEXT,"
                    + KEY_POSITION+ "TEXT,"
                    + KEY_DEPARTMENT + "TEXT,"
                    + KEY_ADMINTYPE + " TEXT"
                    + KEY_EMAIL + " TEXT UNIQUE,"
                    + KEY_VERIFIER + "TEXT"  + ")";

            db.execSQL(CREATE_LOGIN_TABLE);
        }

        // Upgrading database
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            // Drop older table if existed
            db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOGIN);

            // Create tables again
            onCreate(db);
        }

        /**
         * Storing user details in database
         */
        public void addUser(String userid, String password, String fname, String mname, String lname, String position, String department, String admintype,String email, String verifier ) {
            SQLiteDatabase db = this.getWritableDatabase();

            ContentValues values = new ContentValues();
            values.put(KEY_USERID, userid); // Userid
            values.put(KEY_PASSWORD, password); //Pas
            values.put(KEY_FNAME, fname); // Fname
            values.put(KEY_MNAME, mname);   // Mname
            values.put(KEY_LNAME, lname); // Lname
            values.put(KEY_POSITION, position); //Position
            values.put(KEY_DEPARTMENT, department); // Department
            values.put(KEY_ADMINTYPE, admintype);
            values.put(KEY_EMAIL, email); // Department
            values.put(KEY_VERIFIER, verifier);

            // M]
        //    values.put(KEY_UID, uid); // Email
      //      values.put(KEY_CREATED_AT, created_at); // Created At

            // Inserting Row
            db.insert(TABLE_LOGIN, null, values);
            db.close(); // Closing database connection
        }

        /**
         * Getting user data from database
         * */
        public HashMap<String, String> getUserDetails(){
            HashMap<String,String> userID = new HashMap<String,String>();
            String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;

            SQLiteDatabase db = this.getReadableDatabase();
            Cursor cursor = db.rawQuery(selectQuery, null);
            // Move to first row
            cursor.moveToFirst();
            if(cursor.getCount() > 0){
                userID.put("userid", cursor.getString(1));
                userID.put("password", cursor.getString(2));
                userID.put("fname", cursor.getString(3));
                userID.put("mname", cursor.getString(4));
                userID.put("lname", cursor.getString(5));
                userID.put("position", cursor.getString(6));
                userID.put("department", cursor.getString(7));
                userID.put("admintype", cursor.getString(8));
                userID.put("email", cursor.getString(9));
                userID.put("verifier", cursor.getString(10));
            }
            cursor.close();
            db.close();
            // return user
            return userID;
        }

        /**
         * Getting user login status
         * return true if rows are there in table
         * */
        public int getRowCount() {
            String countQuery = "SELECT  * FROM " + TABLE_LOGIN;
            SQLiteDatabase db = this.getReadableDatabase();
            Cursor cursor = db.rawQuery(countQuery, null);
            int rowCount = cursor.getCount();
            db.close();
            cursor.close();

            // return row count
            return rowCount;
        }

        /**
         * Re create database
         * Delete all tables and create them again
         * */
        public void resetTables(){
            SQLiteDatabase db = this.getWritableDatabase();
            // Delete All Rows
            db.delete(TABLE_LOGIN, null, null);
            db.close();
        }
    }

UserFunctions.java:

package com.example.sabre8.library;

import java.util.ArrayList;
import java.util.List;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONObject;

import android.content.Context;

public class UserFunctions {

    private JSONParser jsonParser;

    // Testing in localhost using wamp or xampp 
    // use http://10.0.2.2/ to connect to your localhost ie http://localhost/
    private static String loginURL = "http://10.0.2.2/Adserve1/";
    //private static String registerURL = "http://10.0.2.2/Sabre1/";

    private static String login_tag = "login";
    //private static String register_tag = "register";

    // constructor
    public UserFunctions(){
        jsonParser = new JSONParser();
    }

    /**
     * function make Login Request
     * @param email
     * @param password
     * */
    public JSONObject loginUser(String userid, String password){
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("tag", login_tag));
        params.add(new BasicNameValuePair("userid", userid));
        params.add(new BasicNameValuePair("password", password));
        JSONObject json = jsonParser.makeHttpRequest(loginURL, "POST", params);
        // return json
        // Log.e("JSON", json.toString());
        return json;
    }


    /**
     * Function get Login status
     **/
    public boolean isUserLoggedIn(Context context){
        DatabaseHandler db = new DatabaseHandler(context);
        int count = db.getRowCount();
        if(count > 0){
            // user logged in
            return true;
        }
        return false;
    }

    /**
     * Function to logout user
     * Reset Database
     * */
    public boolean logoutUser(Context context){
        DatabaseHandler db = new DatabaseHandler(context);
        db.resetTables();
        return true;
    }
}

还有我的 logcat 错误：

02-13 20:09:39.481：E/JSON Parser(1305)：解析数据时出错 org.json.JSONException：值

为了更好的衡量，我的 DB_Functions.php：

<?php

class DB_Functions {

    private $db;

    //put your code here
    // constructor
    function __construct() {
        require_once 'DB_Connect.php';
        // connecting to database
        $this->db = new DB_Connect();
        $this->db->connect();
    }

    // destructor
    function __destruct() {

    }

    /**
     * Get user by email and password
     */
    public function getUserByEmailAndPassword($userid, $password) {
        $result = mysql_query("SELECT * FROM user_tb WHERE UserID = '$userid'") or die(mysql_error());
        // check for result 
        $no_of_rows = mysql_num_rows($result);
        if ($no_of_rows > 0) {
            $result = mysql_fetch_array($result);
            // check for password equality
            $pass = $result['password'];
            if ($pass == $password) {
                // user authentication details are correct
                return $result;
            }
        } else {
            // user not found
               return false;
        }
    }

    /**
     * Check user is existed or not
     */
    public function isUserExisted($userid) {
        $result = mysql_query("SELECT UserID from user_tb WHERE UserID = '$userid'");
        $no_of_rows = mysql_num_rows($result);
        if ($no_of_rows > 0) {
            // user existed 
            return true;
        } else {
            // user not existed
            return false;
        }
    }

}

?>

抱歉，代码太长了，但我卡住了。希望你能帮忙。

【问题讨论】：

那一行是唯一的 logcat 条目。
@Saint-Clair 这不是完整的 logcat 输出。
Error of value <br of type java.lang.String cannot converted to JSONObject 的可能重复项

标签： java php android json jsonobject

【解决方案1】：

JSON 库无法解析来自服务器的响应，这就是它抛出 JSONException 的原因。无论出于何种原因，您的 PHP 脚本都没有返回有效的 JSON。

首先，使用 curl 或其他 HTTP 工具向您的脚本发送请求并查看响应是什么。如果有任何 PHP 错误，您可能会在响应中看到它们的 HTML 代码。 Postman for Chrome 非常适合调试 Web 服务。

然后，一旦您修复了 PHP 脚本的任何错误，您就可以使用像 JSONLint 这样的工具来确保它返回的 JSON 是有效的。

【讨论】：