练习

在 Spring 项⽬中，通过 main ⽅法获取到 Controller 类，调⽤ Controller ⾥⾯通过注⼊的⽅式调⽤ Service 类，Service 再通过注⼊的⽅式获取到 Repository 类，Repository 类⾥⾯有⼀个⽅法构建⼀个 User 对象，返回给 main ⽅法。Repository ⽆需连接数据库，使⽤伪代码即可。

User类

package com.java.demo.model;

public class User {
    private int id;
    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

UserController类

package com.java.demo.controller;

import com.java.demo.model.User;
import com.java.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

@Controller
public class UserController {
    @Autowired
    private UserService userService;

    public User getUser() {
        return userService.getUser();
    }
}

UserRepository类

package com.java.demo.repository;

import com.java.demo.model.User;
import org.springframework.stereotype.Repository;

@Repository
public class UserRepository {

    public User getUser() {
        // 伪代码
        User user = new User();
        user.setId(1);
        user.setName("张三");
        return user;
    }
}

UserService类

package com.java.demo.service;

import com.java.demo.model.User;
import com.java.demo.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    public User getUser() {
        return userRepository.getUser();
    }
}

App类

package com.java.demo;

import com.java.demo.controller.UserController;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App {

    public static void main(String[] args) {
        ApplicationContext context =
                new ClassPathXmlApplicationContext("spring-config.xml");
        UserController userController = context.getBean("userController", UserController.class);
        System.out.println(userController.getUser());
    }
}