解析数据时出错org.json.JSONException：输入结束

Question

我正在开发一个连接到mysql数据库的Android应用程序

这是我的错误日志的开始：

    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada E/JSON Parser: Error parsing data org.json.JSONException: End of input at character 0 of 
    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada W/dalvikvm: threadid=11: thread exiting with uncaught exception (group=0x415c9d58)
    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada E/AndroidRuntime: Process: com.example.k12md02.ellieshotenchilada, PID: 29175
    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada E/AndroidRuntime: java.lang.RuntimeException: An error occured while executing doInBackground()
    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada E/AndroidRuntime:     at android.os.AsyncTask$3.done(AsyncTask.java:300)
    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada E/AndroidRuntime:     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
    11-05 12:23:20.801 29175-29221/com.example.k12md02.ellieshotenchilada E/AndroidRuntime:     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)

这是我使用的JSONParser类：

    package com.example.k12md02.ellieshotenchilada;

import android.util.Log;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;

public class JSONParser {

    String charset = "UTF-8";
    HttpURLConnection conn;
    DataOutputStream wr;
    StringBuilder result = new StringBuilder();
    URL urlObj;
    JSONObject jObj = null;
    StringBuilder sbParams;
    String paramsString;

    public JSONObject makeHttpRequest(String url, String method,
                                      HashMap<String, String> params) {

        sbParams = new StringBuilder();
        int i = 0;
        for (String key : params.keySet()) {
            try {
                if (i != 0){
                    sbParams.append("&");
                }
                sbParams.append(key).append("=")
                        .append(URLEncoder.encode(params.get(key), charset));

            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
            i++;
        }

        if (method.equals("POST")) {
            // request method is POST
            try {
                urlObj = new URL(url);

                conn = (HttpURLConnection) urlObj.openConnection();

                conn.setDoOutput(true);

                conn.setRequestMethod("POST");

                conn.setRequestProperty("Accept-Charset", charset);

                conn.setReadTimeout(10000);
                conn.setConnectTimeout(15000);

                conn.connect();

                paramsString = sbParams.toString();

                wr = new DataOutputStream(conn.getOutputStream());
                wr.writeBytes(paramsString);
                wr.flush();
                wr.close();

            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        else if(method.equals("GET")){
            // request method is GET

            if (sbParams.length() != 0) {
                url += "?" + sbParams.toString();
            }

            try {
                urlObj = new URL(url);

                conn = (HttpURLConnection) urlObj.openConnection();

                conn.setDoOutput(false);

                conn.setRequestMethod("GET");

                conn.setRequestProperty("Accept-Charset", charset);

                conn.setConnectTimeout(15000);

                conn.connect();

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

        }

        try {
            //Receive the response from the server
            InputStream in = new BufferedInputStream(conn.getInputStream());
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));

            String line;
            while ((line = reader.readLine()) != null) {
                result.append(line);
            }

            Log.d("JSON Parser", "result: " + result.toString());

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

        conn.disconnect();

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

        // return JSON Object
        return jObj;
    }`enter code here`
}

这是以下活动：

package com.example.k12md02.ellieshotenchilada;

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


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

import android.app.ListActivity;
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.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class AllProductsActivity extends ListActivity {

    // Progress Dialog
    private ProgressDialog pDialog;

    // Creating JSON Parser object
    JSONParser jParser = new JSONParser();

    ArrayList<HashMap<String, String>> menuList;

    // url to get all products list
    //private static String url_all_products = "http://localhost:8383/MENU_GET_ALL_PRODUCTS.php";
    private static String url_all_products = "http://localhost:8383/MENU_GET_ALL_PRODUCTS.php";

    // JSON Node names
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_MENU = "menu";
    private static final String TAG_PRICE = "price";
    private static final String TAG_ITEM = "item";

    // products JSONArray
    JSONArray menu = null;

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

        // Hashmap for ListView
        menuList = new ArrayList<HashMap<String, String>>();

        // Loading products in Background Thread
        new LoadAllmenu().execute();

        // Get listview
        ListView lv = getListView();

        // on selecting single product
        // launching Edit Product Screen
        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {
                // getting values from selected ListItem
                String price = ((TextView) view.findViewById(R.id.price)).getText()
                        .toString();

                // Starting new intent
                Intent in = new Intent(getApplicationContext(),
                        EditProductActivity.class);
                // sending pid to next activity
                in.putExtra(TAG_PRICE, price);

                // starting new activity and expecting some response back
                startActivityForResult(in, 100);
            }
        });

    }

    // Response from Edit Product Activity
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // if result code 100
        if (resultCode == 100) {
            // if result code 100 is received
            // means user edited/deleted product
            // reload this screen again
            Intent intent = getIntent();
            finish();
            startActivity(intent);
        }

    }

    /**
     * Background Async Task to Load all product by making HTTP Request
     * */
    class LoadAllmenu extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(AllProductsActivity.this);
            pDialog.setMessage("Loading products. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        /**
         * getting All products from url
         * */
        protected String doInBackground(String... args) {
            // Building Parameters
            HashMap<String, String> params = new HashMap<String, String>();

            // getting JSON string from URL
            JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

            // Check your log cat for JSON reponse
            Log.d("All Menu Items: ", json.toString());

            try {
                // Checking for SUCCESS TAG
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // products found
                    // Getting Array of Menu items
                    menu = json.getJSONArray(TAG_MENU);

                    // looping through All Products
                    for (int i = 0; i < menu.length(); i++) {
                        JSONObject c = menu.getJSONObject(i);

                        // Storing each json item in variable
                        String price = c.getString(TAG_PRICE);
                        String item = c.getString(TAG_ITEM);

                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        map.put(TAG_PRICE, price);
                        map.put(TAG_ITEM, item);

                        // adding HashList to ArrayList
                        menuList.add(map);
                    }
                } else {
                    // no products found
                    // Launch Add New product Activity
                    Intent i = new Intent(getApplicationContext(),
                            AddToMenuActivity.class);
                    // Closing all previous activities
                    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(i);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after getting all products
            pDialog.dismiss();
            // updating UI from Background Thread
            runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    ListAdapter adapter = new SimpleAdapter(
                            AllProductsActivity.this, menuList,
                            R.layout.list_item, new String[] {TAG_ITEM, TAG_PRICE
                    },
                            new int[] {R.id.item, R.id.price  });
                    // updating listview
                    setListAdapter(adapter);
                }
            });

        }

    }
}

这是我正在使用的PHP文件：

<?php

/*
 * Following code will list all the Menus
 */

// array for JSON response
$response = array();

// include db connect class
require_once __DIR__ . '/menu_db_connect.php';

// connecting to db
//$db = new DB_CONNECT();
// import database connection variables
require_once __DIR__ . '/menu_db_config.php';
$db = mysqli_connect(MENU_DB_SERVER, MENU_DB_USER, MENU_DB_PASSWORD) or die(mysqli_error());
mysqli_select_db($db, "ellieshotenchilada");

// get all Menus from Menu table
$sqlCommand= "SELECT * FROM menu";
$result = mysqli_query( $db, $sqlCommand) or die(mysqli_error());

// check for empty result
if (mysqli_num_rows($result) > 0) {
    // looping through all results
    // Menu node
    $response["Menu"] = array();

    while ($row = mysqli_fetch_array($result)) {
        // temp user array
        $Menu = array();
        $Menu["Item"] = $row["Item"];
        $Menu["Price"] = $row["Price"];
        //  $Menu["pid"] = $row["pid"];
        //  $Menu["created_at"] = $row["created_at"];
        //  $Menu["updated_at"] = $row["updated_at"];

        // push single Menu into final response array
        array_push($response["Menu"], $Menu);
    }
    // success
    $response["success"] = 1;

    // echoing JSON response
    echo json_encode($response);} else {
    // no products found
    $response["success"] = 0;
    $response["message"] = "No products found";

    // echo no users JSON
    echo json_encode($response);
}
?>

我在网上发现了很多类似的错误，但它们都是关于一个与我类似的弃用教程，所以每次我尝试他们的解决方案时都会得到一个无关的错误。