"Method Not Allowed"405问题分析以及解决方法

package com.xxxx.salesforecast.Controller;

import com.xxxx.salesforecast.pojo.User;
import com.xxxx.salesforecast.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

/**
 * 用户外部接口
 *
 * @author : liuke
 * @date : 2022-06-22 14:20
 **/
@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserRepository userRepository;

    /**
     * 插入
     *
     * @param user
     * @return
     */
    @PostMapping
    public String addUser(@RequestBody User user) {
        userRepository.save(user);
        return "success";
    }

    /**
     * 查询全部
     *
     * @return
     */
    @GetMapping("")
    public List<User> getAllUser() {
        List<User> userList = userRepository.findAll();
        return userList;
    }

    /**
     * 根据 id 删除
     * @param id
     * @return
     */
    @DeleteMapping("/{id}")
    public String deleteUserById(@PathVariable Integer id){
        userRepository.deleteById(id.intValue());
        return "success";
    }
}