Question

我遇到问题，有效的JSON字符串无法成为JSON对象。

我测试了来自服务器的响应，它是一个有效的JSON。

我已经在互联网上查了一下，它是关于UTF-8与DOM的问题。但即使我将Notepad ++中的charset更改为没有DOM的UTF-8，仍然会出现同样的错误。

我的代码：

<?php
    require_once("Connection/conn.php");


    //parse JSON and get input
    $json_string = $_POST['json'];
    $json_associative_array = json_decode($json_string,true);

    $userId = $json_associative_array["userId"];
    $password = $json_associative_array["password"];
    $userType = $json_associative_array["userType"];    

    //get the resources
    $json_output_array = array();

    $sql = "SELECT * FROM account WHERE userId = '$userId' AND password = '$password' AND userType = '$userType'";  
    $result = mysql_query($sql);  

    //access success?
    if (!$result) {
        die('Invalid query: ' . mysql_error());
        $json_output_array["status"] = "query failed";
    }
    else{
        $json_output_array["status"] = "query success";
    }

    //find the particular user?
    if (mysql_num_rows($result) > 0){
        $json_output_array["valid"] = "yes";
    }
    else{
        $json_output_array["valid"] = "no";
    }

    //output JSON 
    echo json_encode($json_output_array);
?>

Android代码：

public boolean login() {
        // instantiates httpclient to make request
        DefaultHttpClient httpClient = new DefaultHttpClient();

        // url with the post data
        String url = SERVER_IP + "/gc/login.php";

        JSONObject holder = new JSONObject();
        try {
            holder.put("userId", "S1");
            holder.put("password", "s12345");
            holder.put("userType", "supervisor");
        } catch (JSONException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        Log.d("JSON", holder.toString());


        // HttpPost
        HttpPost httpPost = new HttpPost(url);


        //FormEntity
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        nameValuePairs.add(new BasicNameValuePair("json", holder.toString()));

        try {
            httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        } catch (UnsupportedEncodingException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        // execution and response
        boolean valid = false; 
        try {
            HttpResponse response = httpClient.execute(httpPost);

            Log.d("post request", "finished execueted");
            String responseString = getHttpResponseContent(response);
            Log.d("post result", responseString);

            //parse JSON
            JSONObject jsonComeBack = new JSONObject(responseString);
            String validString = jsonComeBack.getString("valid");
            valid = (validString.equals("yes"))?true:false;

        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



        return valid;

    }

    private String getHttpResponseContent(HttpResponse response) {

        String responseString = "";

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

            String line = "";

            while ((line = rd.readLine()) != null) {
                responseString += line ;
            }
            rd.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return responseString;
    }

JSON来自服务器：

{
    "status": "query success",
    "valid": "yes"
}

取消格式化JSON：

{"status":"query success","valid":"yes"}

当我将其复制到记事本++时，它变为?{"status":"query success","valid":"yes"} 似乎有一个看不见的角色。

Answer 1

我用MuhammedPasha提供的solution修复了它，子串JSON字符串以删除不可见的字符。我将JSON字符串从1子串起来解决我的问题。

有一种方法可以检测那些不可见的字符，将日志结果复制到记事本++。（复制！没有打字！）如果有任何？（问号），它们表示有一些不可见的字符。

Answer 2

我遇到了同样的问题。也许您需要在没有unicode签名（BOM）的情况下进行保存。

JSONException：类型java.lang.String的值无法转换为JSONObject

2 个答案: