Bean named ‘userServiceImpl‘ is expected to be of type ‘com.woniu.service.UserServiceImpl‘ but was a

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错误代码：

@RestController
@RequestMapping("/user")
public class UserServlet {

    @Autowired
    private UserServiceImpl userServiceImpl;

    @PostMapping
    public boolean addUser(@RequestBody User user) {
        System.out.println("user = " + user);
        return userServiceImpl.insertUser(user);
    }

    @DeleteMapping(value = "/{id}")
    public Result deleteUser(@PathVariable Integer id) {
        boolean b = userServiceImpl.deleteUserById(id);
        String s = new String(String.valueOf(b));


        return new Result( b ? Code.DELETE_OK : Code.DELETE_ERR, s,  b ? "成功":"失败" );
    }

    @PutMapping
    public boolean updateUser(@RequestBody User user) {
        return userServiceImpl.updateUser(user);
    }

    @GetMapping(value = "/{id}")
    public User queryUserById(@PathVariable Integer id) {

        return userServiceImpl.queryUserById(id);
    }

    @GetMapping
    public List<User> queryAllUsers() {

        return userServiceImpl.queryAllUsers();
    }

}

错误原因：

因为UserServiceImpl 使用了方法，因此spring会使用注解反射对UserServiceImpl进行操作。spring使用反射进行操作时，代理类与被代理类都是UserService接口的实现类新生成的代理类只能向上转型为接口类型，不能强转给同等级UserServiceImpl。

修改后的代码：

package com.woniu.controller;

import com.woniu.bean.Code;
import com.woniu.bean.Result;
import com.woniu.bean.User;
import com.woniu.service.UserService;
import com.woniu.service.UserServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.List;

/**
 * @author vampire
 * @date 2022-05-07
 * @desc
 */
@RestController
@RequestMapping("/user")
public class UserServlet {

    @Autowired
    private UserService userService;

    @PostMapping
    public boolean addUser(@RequestBody User user) {
        System.out.println("user = " + user);
        return userService.insertUser(user);
    }

    @DeleteMapping(value = "/{id}")
    public Result deleteUser(@PathVariable Integer id) {
        boolean b = userService.deleteUserById(id);
        String s = new String(String.valueOf(b));


        return new Result( b ? Code.DELETE_OK : Code.DELETE_ERR, s,  b ? "成功":"失败" );
    }

    @PutMapping
    public boolean updateUser(@RequestBody User user) {
        return userService.updateUser(user);
    }

    @GetMapping(value = "/{id}")
    public User queryUserById(@PathVariable Integer id) {

        return userService.queryUserById(id);
    }

    @GetMapping
    public List<User> queryAllUsers() {

        return userService.queryAllUsers();
    }

}

本文标签： userServiceImplexpectedbeannamedService