After ajax is executed, it jumps to background processing, but after processing, it jumps to other pages.

ajax:

$(".get-code").click(function(){        
    var user_number=$("input[name=user_number]").val();       
       alert(user_number);       
        $.ajax({type : "post",
            url : "user/validate",
            dataType : "json",
            data : {"phone" : user_number},
            success : function(data) {                                
            }
    
        });
       
   });

Button

 <button class="get-code">测试</button>

Backstage

@ResponseBody
@RequestMapping("/validate")
public Object validate(HttpSession session,String phone){
    Integer result1=(int)((Math.random()*9+1)*100000);
    String str=Integer.toString(result1, 10);
    String result=    str;    /*Sampler.samlerInfo(phone, null);*/
    System.out.println("随机数为："+result);
    session.setAttribute("result", result+"");
    return null;
}

The control has output, indicating that it has come in,

In the end it jumped to other pages

The console also reported an error