springboot报错笔记(1) :java.lang.IllegalArgumentException: Unknown return value type: java.lang.Integer

报错:java.lang.IllegalArgumentException: Unknown return value type: java.lang.Integer

Solution:
Add the annotation @ResponseBody to the controller.

• The function of @ResponseBody annotation is usually to convert the controller's method parameters into JSON format for data return, and write it in the body area of ​​the response object.

code show as below:

@RequestMapping("/LoginUser")
@ResponseBody
　　public User LoginUser(User user){
    
    
　　　　return user;
　　}

Then the data displayed on the page is displayed in JSON format , such as:
　 {"name":"张三","age":18}