Java 字符串到 JsonObject 返回 null

Question

I'm trying to convert String to JSONObject, but always returns null.

At front page, I used $.ajax to send post data,

    var jsonInfo = '{"search_key":"apple", "person":{"name":"test","age":20}}';
    
    var testApi = $.ajax({
        type : "POST", 
        url : "/test/testPerson",
        dataType : "json",
        data : {
            "apiData" : JSON.stringify(jsonInfo)
        }
    })
    .done(function(data, status){
        console.log("success!" + status);
    });

At Servlet, I tried to get the JSONObject with following code:

    JSONObject jsonObject = new JSONObject();
    JSONParser parser = new JSONParser();
    Object obj = null;
    try {
        obj = parser.parse(reqApiKey2);
    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    
    jsonObject = (JSONObject) obj;

But I got an error, java.lang.ClassCastException: java.lang.String cannot be cast to org.json.simple.JSONObject at jsonObject = (JSONObject) obj;

I tried to send the data with JSON.parse(jsonInfo) from web, but same result.

Thank you for your advices, and helps.

Answer 1

Your client code is turning the json in the variable jsonInfo into a plain String. Don't do that - it's already JSON!

Change:

data : {
    "apiData" : JSON.stringify(jsonInfo)
}

to:

data : {
    "apiData" : jsonInfo
}

Your server code is correctly deserializing it as String , not an object.