The server refused this request because the request entity is in a format not supported by the requested resource for the requested method
原因是传入json，未指定contentType : \'application/json\',
解决：ajax方法中加入 contentType : \'application/json\',
$.ajax({
type:"post",
url:"/addStudent",
contentType : \'application/json\',
data:data,
success:function(result) {
alert(JSON.stringify(result));
},
error:function() {
alert("error");
}
});