无法获取正确的json字符串

Question

我目前正在使用一个登录users.Upon登录的Android应用程序，允许用户自己创建一个文件名。但是，执行此函数时，如下所示，返回json包含登录详细信息的JSON字符串。

我正在使用xmapp服务器。

有没有人知道获取createNewFile详细信息的返回json字符串的正确方法？

public JSONObject createNewFile(String f_id, String userid, String name){
    // Building Parameters
    List params= new ArrayList();

    params.add(new BasicNameValuePair("tag", createFile));
    params.add(new BasicNameValuePair("fid", fid));
    params.add(new BasicNameValuePair("userid", userid));
    params.add(new BasicNameValuePair("name", name));


    // getting JSON Object
    JSONObject json =  jsonParser.getJSONFromUrl(URL, params);
    // return json
    return json;
}

//用于登录

public JSONObject loginUsers(String email, String password){
        // Building Parameters
        List params = new ArrayList();
        params.add(new BasicNameValuePair("tag", login_tag));
        params.add(new BasicNameValuePair("email", email));
        params.add(new BasicNameValuePair("password", password));
        JSONObject json = jsonParser.getJSONFromUrl(loginURL, params);
        // return json
        Log.e("JSON", json.toString());
        return json;
    }

这是我的JSONPARSER课程。

public class JSONParser {

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

    // constructor
    public JSONParser() {

    }

    public JSONObject getJSONFromUrl(String url, List params) {

        // Making HTTP request
        try {
            // 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();

        } 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();
            Log.e("JSON", json);

        } 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;

    }

}

Php文件：

DB_Functions

public function storeFile($fid, $userid, $name){

    $con = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD);

    mysqli_select_db($con, DB_DATABASE);


    $result = mysqli_query($con,"INSERT INTO file_info(fid, userid, name) VALUES('$fid', '$userid', '$name',  NOW())");
    // check for successful store
    if ($result) {
        // get file details 
        $fid = mysqli_insert_id($con); // last inserted id
        $result = mysqli_query($con,"SELECT * FROM file_info WHERE fid = $fid");
        // return file details
        return mysqli_fetch_array($result);
    } else {
        return false;
    }
}

的index.php

 //add_file
 if ($tag == 'add_file') {
        // Request type is add new file
        $fid = $_POST['fid'];
        $userid = $_POST['userid'];
        $name = $_POST['name'];

            $file_info= $db->storeFile($fid, $userid, $name);
            if ($file_info) {
                // user stored successfully
                $response["success"] = 1;
                $response["fid"] = $file_info["fid"];
                $response["file_info"]["userid"] = $file_info["userid"];
                $response["file_info"]["name"] = $ufile_info["name"];


                echo json_encode($response);

            } else {
                // user failed to store
                $response["error"] = 1;
                $response["error_msg"] = "Error occured in Adding";
                echo json_encode($response);
            }
        }else {
        echo "Invalid Request";
    } 



} else {
    echo "Access Denied";
}

面临错误：

Invalid RequestInvalid Requestn
Error parsing data org.json.JSONException: Value Invalid of type java.lang.String cannot be converted to JSONObject