java无法从JSONArray获取JSONObject

Question

我的php：

 <?php

 $con=mysqli_connect("localhost","xxx","xxx","xxx");

 $result = mysqli_query($con, "SELECT username, x,y FROM user");

 $jsonData = array();
while($array = mysqli_fetch_assoc($result)){
$jsonData[] = $array;
}

echo json_encode($jsonData);


mysqli_close($con);
?>

我将数据提取到JSONArray:[{"username":"one","x":"22.","y":"55"},{"username":"two","x":2,"y":5}]

Android代码：

        //Connect to mysql.
        HttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost("http:example.com/fetchCoordinates.php");

        //Getting response
        HttpResponse response = httpClient.execute(httpPost);
        String responseBody = EntityUtils.toString(response.getEntity());

        //Trying to get fetch from array.
        JSONArray array = new JSONArray(responseBody);
        JSONObject jsonObject = array.getJSONObject(0);
        double x = jsonObject.getDouble("x");

Eror：

org.json.JSONArray cannot be converted to JSONObject

它不起作用。我受够了

Answer 1

问题出在我的PHP代码中

出了什么问题：

while($array = mysqli_fetch_rows($result)){
   $jsonData[] = $array;}

什么是正确的：

while($array = mysqli_fetch_assoc($result)){
   $jsonData[] = $array;}

为什么

First method (fetch_rows) gave me not JSONArray with JSONObjects inside, but instead I got JSONArray with JSONStrings inside.

In java code I tried to receive JSONObject from JSONArray, but I was getting error, because there wasn't any objects(there were strings).

Answer 2

要从数组中创建json对象，数组必须是关联的，这样您就可以将代码更改为这个或那个

  while($array = mysqli_fetch_assoc($result)){
       $jsonData[] = $array;
  }

Answer 3

JSON是有效的，但问题是它不包含JSONObject。它只是一个字符串数组。要真正从中获取JSONObject，它需要是一个实际JSONObject数组。尝试如下格式化数据：

[{
    "name": "one",
    "num1": "22",
    "num2": "55"
}, 
{
    "name": "two",
    "num1": "2",
    "num2": "5"
}]

请注意，包含在方括号[]中的数组包含逗号分隔的JSONObject，它们是包含在大括号{}中的键值对

你应该仔细阅读如何正确格式化JSON。这里有一个很好的资源：http://www.w3schools.com/json/default.asp

另请参见此答案以获取一些有用的信息： How do you represent a JSON array of strings?