ajax得到后端数据一直提示为[object Object]解决方法

前段ajax

<script type="text/javascript">

    function requestJson() {
        $.ajax({
        type : "post",
        url : "checkJosn",
        dataType:"json",
        success : function(msg) {
            alert(msg);
        }
        });
    }
</script

后端Controller

@Controller
public class JsonController {

    @ResponseBody
    @RequestMapping(value = "/checkJosn")
    public Student checkJosn(){
        Student student = new Student();
        student.setId(12);
        student.setUsername("chen");
        Address address = new Address();
        address.setCity("wuhan");
        student.setAddress(address);
        System.out.println("进入");
        return student;
    }

}

提交后，提示object，而注意到浏览器响应里已经得到了json字符串，为啥alert不出来

百度了好久，使用  alert(JSON.stringify(msg));方法可以弹出json字符串。JSON.stringify()方法是将一个JavaScript值(对象或者数组)转换为一个 JSON字符串

修改后ajax代码

<script type="text/javascript">

    function requestJson() {
        $.ajax({
        type : "post",
        url : "checkJosn",
        dataType:"json",
        success : function(msg) {
            alert(JSON.stringify(msg));
        }
        });
    }
</script>

结果：