只接收一个List作为入参的话不报错，
下方为代码：
前台：
$.ajax({

    type:"post",
    url: 'add',
    contentType:"application/json; charset=utf-8",
    dataType:"json",
    data:JSON.stringify([{id:1,name:"hello"},{id:2,name:"hello"}]),
    success:function(data){
        console.log(data);
    }
})

后台：
@ResponseBody

@RequestMapping(value = "add", consumes = "application/json; charset=utf-8")
public String add(@RequestBody List<Tag> param) {
    System.out.println("param:" + param);
    return "成功";
}

前台控制台显示的数据格式为：
[{id: 1, name: "hello"}, {id: 2, name: "hello"}]
0:{id: 1, name: "hello"}
1:{id: 2, name: "hello"}

那如果我后台想接受一个字符串和一个list该怎么写呢，

后台代码改为：
@ResponseBody

@RequestMapping(value = "add", consumes = "application/json; charset=utf-8")
public String add(@RequestBody String content, @RequestBody List<Tag> param) {

前台应该怎么写？