Problem mit JSON-String: "E/JSON Parser(619)"

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  • Forum-Beiträge: 9

31.07.2014, 11:27:34 via Website

Hallo, ich folgte den Hinweisen von einem Tutorial *1. Ich wollte eine Android-App erstellen, die über ein php-Script auf eine mySql-Datenbank zugreift.

*1 = mybringback.com/tutorial-series/12992/android-mysql-php-json-part-2-setting-up-a-xampp-server-and-mysql/

Im LogCat wird u.a. folgender Fehler angezeigt:

E/JSON Parser(619): Error parsing data org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject

Kann mir jemand bei der Behebung des Fehlers helfen?

Hier sind die erforderlichen Daten. Zuerst die Codes für die AndroidApplication. Dahinter folgen die php-scripts.

Es gibt die folgenden Klassen:
- JSONParser.java
- Login.java
- MainActivity.java
- Register.java

JSONParser.java

package com.example.mysqltest;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }


    public JSONObject getJSONFromUrl(final String url) {

        // Making HTTP request
        try {
            // Construct the client and the HTTP request.
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            // Execute the POST request and store the response locally.
            HttpResponse httpResponse = httpClient.execute(httpPost);
            // Extract data from the response.
            HttpEntity httpEntity = httpResponse.getEntity();
            // Open an inputStream with the data content.
            is = httpEntity.getContent();

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

        try {
            // Create a BufferedReader to parse through the inputStream.
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            // Declare a string builder to help with the parsing.
            StringBuilder sb = new StringBuilder();
            // Declare a string to store the JSON object data in string form.
            String line = null;

            // Build the string until null.
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }

            // Close the input stream.
            is.close();
            // Convert the string builder data to an actual string.
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // Try to parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // Return the JSON Object.
        return jObj;

    }


    // function get json from url
    // by making HTTP POST or GET mehtod
    public JSONObject makeHttpRequest(String url, String method,
            List<NameValuePair> params) {

        // Making HTTP request
        try {

            // check for request method
            if(method == "POST"){
                // request method is POST
                // defaultHttpClient
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(new UrlEncodedFormEntity(params));

                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();

            }else if(method == "GET"){
                // request method is GET
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String paramString = URLEncodedUtils.format(params, "utf-8");
                url += "?" + paramString;
                HttpGet httpGet = new HttpGet(url);

                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();
            }           

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

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}

Login.java

package com.example.mysqltest;

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

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

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class Login extends Activity implements OnClickListener{

    private EditText user, pass;
    private Button mSubmit, mRegister;

     // Progress Dialog
    private ProgressDialog pDialog;

    // JSON parser class
    JSONParser jsonParser = new JSONParser();

    //php login script location:

    //localhost :
    //testing on your device
    //put your local ip instead,  on windows, run CMD > ipconfig
    //or in mac's terminal type ifconfig and look for the ip under en0 or en1

    //testing on Emulator:
    private static final String LOGIN_URL = ".../webservice/login.php";

    //JSON element ids from repsonse of php script:
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_MESSAGE = "message";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);

        //setup input fields
        user = (EditText)findViewById(R.id.username);
        pass = (EditText)findViewById(R.id.password);

        //setup buttons
        mSubmit = (Button)findViewById(R.id.login);
        mRegister = (Button)findViewById(R.id.register);

        //register listeners
        mSubmit.setOnClickListener(this);
        mRegister.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {
        case R.id.login:
                new AttemptLogin().execute();
            break;
        case R.id.register:
                Intent i = new Intent(this, Register.class);
                startActivity(i);
            break;

        default:
            break;
        }
    }

    class AttemptLogin extends AsyncTask<String, String, String> {

         /**
         * Before starting background thread Show Progress Dialog
         * */
        boolean failure = false;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(Login.this);
            pDialog.setMessage("Attempting login...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String... args) {
            // TODO Auto-generated method stub
             // Check for success tag
            int success;
            String username = user.getText().toString();
            String password = pass.getText().toString();
            try {
                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair("username", username));
                params.add(new BasicNameValuePair("password", password));

                Log.d("request!", "starting");
                // getting product details by making HTTP request
                JSONObject json = jsonParser.makeHttpRequest(
                       LOGIN_URL, "POST", params);

                // check your log for json response
                Log.d("Login attempt", json.toString());

                // json success tag
                success = json.getInt(TAG_SUCCESS);
                if (success == 1) {
                    Log.d("Login Successful!", json.toString());
                    Intent i = new Intent(Login.this, ReadComments.class);
                    finish();
                    startActivity(i);
                    return json.getString(TAG_MESSAGE);
                }else{
                    Log.d("Login Failure!", json.getString(TAG_MESSAGE));
                    return json.getString(TAG_MESSAGE);

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

            return null;

        }
        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog once product deleted
            pDialog.dismiss();
            if (file_url != null){
                Toast.makeText(Login.this, file_url, Toast.LENGTH_LONG).show();
            }

        }

    }

}

MainActivity.java

package com.example.mysqltest;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container,
                false);
        return rootView;
    }
}

}

Register.java

package com.example.mysqltest;

import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class Register extends Activity implements OnClickListener{

private EditText user, pass;
private Button  mRegister;

 // Progress Dialog
private ProgressDialog pDialog;

// JSON parser class
JSONParser jsonParser = new JSONParser();

//php login script

//localhost :
//testing on your device
//put your local ip instead,  on windows, run CMD > ipconfig
//or in mac's terminal type ifconfig and look for the ip under en0 or en1

private static final String LOGIN_URL = ".../webservice/register.php";


//ids
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.register);

    user = (EditText)findViewById(R.id.username);
    pass = (EditText)findViewById(R.id.password);

    mRegister = (Button)findViewById(R.id.register);
    mRegister.setOnClickListener(this);

}

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub

            new CreateUser().execute();

}

class CreateUser extends AsyncTask<String, String, String> {

     /**
     * Before starting background thread Show Progress Dialog
     * */
    boolean failure = false;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(Register.this);
        pDialog.setMessage("Creating User...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show();
    }

    @Override
    protected String doInBackground(String... args) {
        // TODO Auto-generated method stub
         // Check for success tag
        int success;
        String username = user.getText().toString();
        String password = pass.getText().toString();
        try {
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("username", username));
            params.add(new BasicNameValuePair("password", password));

            Log.d("request!", "starting");

            //Posting user data to script
            JSONObject json = jsonParser.makeHttpRequest(
                   LOGIN_URL, "POST", params);

            // full json response
            Log.d("Login attempt", json.toString());

            // json success element
            success = json.getInt(TAG_SUCCESS);
            if (success == 1) {
                Log.d("User Created!", json.toString());
                finish();
                return json.getString(TAG_MESSAGE);
            }else{
                Log.d("Login Failure!", json.getString(TAG_MESSAGE));
                return json.getString(TAG_MESSAGE);

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

        return null;

    }
    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(String file_url) {
        // dismiss the dialog once product deleted
        pDialog.dismiss();
        if (file_url != null){
            Toast.makeText(Register.this, file_url, Toast.LENGTH_LONG).show();
        }

    }

}

}

PHP-Scripts:

.../webservice/login.php

<?php

//load and connect to MySQL database stuff
require("config.inc.php");

if (!empty($_POST)) {
    //gets user's info based off of a username.
    $query = " 
            SELECT 
                id, 
                user, 
                password
            FROM users 
            WHERE 
                user = :username 
        ";

    $query_params = array(
        ':username' => $_POST['username']
    );

    try {
        $stmt   = $db->prepare($query);
        $result = $stmt->execute($query_params);
    }
    catch (PDOException $ex) {
        // For testing, you could use a die and message. 
        //die("Failed to run query: " . $ex->getMessage());

        //or just use this use this one to product JSON data:
        $response["success"] = 0;
        $response["message"] = "Database Error1. Please Try Again!";
        die(json_encode($response));

    }

    //This will be the variable to determine whether or not the user's information is correct.
    //we initialize it as false.
    $validated_info = false;

    //fetching all the rows from the query
    $row = $stmt->fetch();
    if ($row) {
        //if we encrypted the password, we would unencrypt it here, but in our case we just
        //compare the two passwords
        if ($_POST['password'] === $row['password']) {
            $login_ok = true;
        }
    }

    // If the user logged in successfully, then we send them to the private members-only page 
    // Otherwise, we display a login failed message and show the login form again 
    if ($login_ok) {
        $response["success"] = 1;
        $response["message"] = "Login successful!";
        die(json_encode($response));
    } else {
        $response["success"] = 0;
        $response["message"] = "Invalid Credentials!";
        die(json_encode($response));
    }
} else {
?>
        <h1>Login</h1> 
        <form action="login.php" method="post"> 
            Username:<br /> 
            <input type="text" name="username" placeholder="username" /> 
            <br /><br /> 
            Password:<br /> 
            <input type="password" name="password" placeholder="password" value="" /> 
            <br /><br /> 
            <input type="submit" value="Login" /> 
        </form> 
        <a href="register.php">Register</a>
    <?php
}

?> 

.../webservice/register.php

<?php

/*
Our "config.inc.php" file connects to database every time we include or require
it within a php script.  Since we want this script to add a new user to our db,
we will be talking with our database, and therefore,
let's require the connection to happen:
*/
require("config.inc.php");

//if posted data is not empty
if (!empty($_POST)) {
    //If the username or password is empty when the user submits
    //the form, the page will die.
    //Using die isn't a very good practice, you may want to look into
    //displaying an error message within the form instead.  
    //We could also do front-end form validation from within our Android App,
    //but it is good to have a have the back-end code do a double check.
    if (empty($_POST['username']) || empty($_POST['password'])) {


        // Create some data that will be the JSON response 
        $response["success"] = 0;
        $response["message"] = "Please Enter Both a Username and Password.";

        //die will kill the page and not execute any code below, it will also
        //display the parameter... in this case the JSON data our Android
        //app will parse
        die(json_encode($response));
    }

    //if the page hasn't died, we will check with our database to see if there is
    //already a user with the username specificed in the form.  ":user" is just
    //a blank variable that we will change before we execute the query.  We
    //do it this way to increase security, and defend against sql injections
    $query        = " SELECT 1 FROM users WHERE user = :user";
    //now lets update what :user should be
    $query_params = array(
        ':user' => $_POST['username']
    );

    //Now let's make run the query:
    try {
        // These two statements run the query against your database table. 
        $stmt   = $db->prepare($query);
        $result = $stmt->execute($query_params);
    }
    catch (PDOException $ex) {
        // For testing, you could use a die and message. 
        //die("Failed to run query: " . $ex->getMessage());

        //or just use this use this one to product JSON data:
        $response["success"] = 0;
        $response["message"] = "Database Error1. Please Try Again!";
        die(json_encode($response));
    }

    //fetch is an array of returned data.  If any data is returned,
    //we know that the username is already in use, so we murder our
    //page
    $row = $stmt->fetch();
    if ($row) {
        // For testing, you could use a die and message. 
        //die("This username is already in use");

        //You could comment out the above die and use this one:
        $response["success"] = 0;
        $response["message"] = "I'm sorry, this username is already in use";
        die(json_encode($response));
    }

    //If we have made it here without dying, then we are in the clear to 
    //create a new user.  Let's setup our new query to create a user.  
    //Again, to protect against sql injects, user tokens such as :user and :pass
    $query = "INSERT INTO users ( user, password ) VALUES ( :user, :pass ) ";

    //Again, we need to update our tokens with the actual data:
    $query_params = array(
        ':user' => $_POST['username'],
        ':pass' => $_POST['password']
    );

    //time to run our query, and create the user
    try {
        $stmt   = $db->prepare($query);
        $result = $stmt->execute($query_params);
    }
    catch (PDOException $ex) {
        // For testing, you could use a die and message. 
        //die("Failed to run query: " . $ex->getMessage());

        //or just use this use this one:
        $response["success"] = 0;
        $response["message"] = "Database Error2. Please Try Again!";
        die(json_encode($response));
    }

    //If we have made it this far without dying, we have successfully added
    //a new user to our database.  We could do a few things here, such as 
    //redirect to the login page.  Instead we are going to echo out some
    //json data that will be read by the Android application, which will login
    //the user (or redirect to a different activity, I'm not sure yet..)
    $response["success"] = 1;
    $response["message"] = "Username Successfully Added!";
    echo json_encode($response);

    //for a php webservice you could do a simple redirect and die.
    //header("Location: login.php"); 
    //die("Redirecting to login.php");


} else {
?>
    <h1>Register</h1> 
    <form action="register.php" method="post"> 
        Username:<br /> 
        <input type="text" name="username" value="" /> 
        <br /><br /> 
        Password:<br /> 
        <input type="password" name="password" value="" /> 
        <br /><br /> 
        <input type="submit" value="Register New User" /> 
    </form>
    <?php
}

?>

** .../webservice/config.inc.php**

<?php 

    // These variables define the connection information for your MySQL database 
    $host = "mysql.secretservername"; 
    $dbname = "database1";     
    $username = "USER123456"; 
        $password = "xXxXxxXXx"; 




    // UTF-8 is a character encoding scheme that allows you to conveniently store 
    // a wide varienty of special characters, like &cent; or &euro;, in your database. 
    // By passing the following $options array to the database connection code we 
    // are telling the MySQL server that we want to communicate with it using UTF-8 
    // See Wikipedia for more information on UTF-8: 
    $options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8'); 

    // A try/catch statement is a common method of error handling in object oriented code. 
    // First, PHP executes the code within the try block.  If at any time it encounters an 
    // error while executing that code, it stops immediately and jumps down to the 
    // catch block.  For more detailed information on exceptions and try/catch blocks: 

    try 
    { 
        // This statement opens a connection to your database using the PDO library 
        // PDO is designed to provide a flexible interface between PHP and many 
        // different types of database servers.  For more information on PDO: 
        $db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options); 
    } 
    catch(PDOException $ex) 
    { 
        // If an error occurs while opening a connection to your database, it will 
        // be trapped here.  The script will output an error and stop executing. 
        // Note: On a production website, you should not output $ex->getMessage(). 
        // It may provide an attacker with helpful information about your code 
        // (like your database username and password). 
        die("Failed to connect to the database: " . $ex->getMessage()); 
    } 

    // This statement configures PDO to throw an exception when it encounters 
    // an error.  This allows us to use try/catch blocks to trap database errors. 
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); 

    // This statement configures PDO to return database rows from your database using an associative 
    // array.  This means the array will have string indexes, where the string value 
    // represents the name of the column in your database. 
    $db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC); 

    // This block of code is used to undo magic quotes.  Magic quotes are a terrible 
    // feature that was removed from PHP as of PHP 5.4.  However, older installations 
    // of PHP may still have magic quotes enabled and this code is necessary to 
    // prevent them from causing problems.  For more information on magic quotes: 
    if(function_exists('get_magic_quotes_gpc') &amp;&amp; get_magic_quotes_gpc()) 
    { 
        function undo_magic_quotes_gpc(&amp;$array) 
        { 
            foreach($array as &amp;$value) 
            { 
                if(is_array($value)) 
                { 
                    undo_magic_quotes_gpc($value); 
                } 
                else 
                { 
                    $value = stripslashes($value); 
                } 
            } 
        } 

        undo_magic_quotes_gpc($_POST); 
        undo_magic_quotes_gpc($_GET); 
        undo_magic_quotes_gpc($_COOKIE); 
    } 

    // This tells the web browser that your content is encoded using UTF-8 
    // and that it should submit content back to you using UTF-8 
    header('Content-Type: text/html; charset=utf-8'); 

    // This initializes a session.  Sessions are used to store information about 
    // a visitor from one web page visit to the next.  Unlike a cookie, the information is 
    // stored on the server-side and cannot be modified by the visitor.  However, 
    // note that in most cases sessions do still use cookies and require the visitor 
    // to have cookies enabled.  For more information about sessions:
    session_start(); 

    // Note that it is a good practice to NOT end your PHP files with a closing PHP tag. 
    // This prevents trailing newlines on the file from being included in your output, 
    // which can cause problems with redirecting users.

?>

Die einzige Änderung bei mir ist die, dass ich eine Spalte der Datenbank nicht so benannt habe, wie im Tutorial. Die php-scripts sind dafür aber bereits angepasst und sämtliche Anfragen funktionieren problemlos über den webbrowser.

— geändert am 31.07.2014, 11:30:03

Antworten
  • Forum-Beiträge: 9

31.07.2014, 12:19:27 via Website

das script antwortet folgendermaßen:

bei login.php:

{"success":1,"message":"Login successful!"}

bei register.php:
{"success":1,"message":"Username Successfully Added!"}
bzw. wenn username bereits vergeben:
{"success":0,"message":"I'm sorry, this username is already in use"}

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