JSON parse error: Unexpected character (‘‘‘ (code 39)): was expecting double-quote to start ......_unexpected character (''' (code 39)): was expectin

在springmvc和jsp模拟ajax的异步请求中遇到这个问题。

完整的错误信息：

JSON parse error: Unexpected character (''' (code 39)): was expecting double-quote to start field name; nested exception is com.fasterxml.jackson.core.JsonParseException: Unexpected character (''' (code 39)): was expecting double-quote to start field name

错误原因：前端ajax请求中json的格式不对。数组的外围应该是单引号包裹，内部的key&value对用双引号包裹。

如下所示.。

           $.ajax(
                {
                    url:"testAjax",
                    contentType:"application/json;charset=UTF-8",
                    //正确的写法
                    data:'{"username":"zs","password":"12456","age":"18"}',
                    //错误的写法
                    data:"{'username':'zs','password':'12456','age':'18'}",
                    dataType:"json",
                    type:"post",
                    success:function (data) {
                    //    data是服务器端响应的数据
                        alert(data);
                        alert(data.username)
                    }
                }