Spring基于注解分层开发的案例实现

模拟一个User表的操作

User类、控制层类、dao接口 及实现类 、serivice层接口 及实现类

由于使用的maven的开发实现，所以需要先把maven的各项配置给处理好。第一步是增加spring的各项jar依赖。

1.pom.xml文件的使用

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.aaa</groupId>
    <artifactId>spring05_layer</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!--依赖 -->
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.3.8</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
        </dependency>
    </dependencies>

</project>

下载完毕jar后，看下图所示：

2.在resources目录下建立spring.xml的配置文件，需要增加对目录的包扫描

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
    <!--1.使用注解，启动包扫描 -->
    <context:component-scan base-package="com.aaa"/>
</beans>

3.针对之前的项目操作，在java目录下建立像一个的包，分别是entity、dao、controller、service包,这些子包统一建立在com.aaa目录下。参考目录结构图如下所示：

   3.1 entity下的User实体类如下

package com.aaa.entity;

import lombok.AllArgsConstructor;
import lombok.NoArgsConstructor;
import lombok.ToString;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class User {
    @Value("22")
    private Integer id;
    @Value("乔布斯")
    private String name;
    private Integer age;
    private String hobby;

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

3.2 dao包下的接口及其实现类

    UserDao接口参考代码如下所示：

package com.aaa.dao;

import com.aaa.entity.User;

import java.util.List;

public interface IUserDao {
    public void saveUser(User user);
    public void updateUser(User user);
    public void delUserById(Integer id);
    public List<User> selAllUsers();
    public List<User>seleUser(User user);
    public User selUserByCondition(User user);
}

UserDao接口的UserDaoImpl参考代码如下所示：

package com.aaa.dao;

import com.aaa.entity.User;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository("userdao")
public class IUserDaoImpl implements IUserDao{
    public void saveUser(User user) {
        System.out.println("执行增加操作");
    }

    public void updateUser(User user) {
        System.out.println("执行更新操作");
    }

    public void delUserById(Integer id) {

    }

    public List<User> selAllUsers() {
        return null;
    }

    public List<User> seleUser(User user) {
        return null;
    }

    public User selUserByCondition(User user) {
        return null;
    }
}

IUserService接口的代码参考如下，目前只实现第一个功能；

package com.aaa.service;

import com.aaa.entity.User;

import java.util.List;

public interface IUserService {
    public void saveUser(User user);
    public void updateUser(User user);
    public void delUserById(Integer id);
    public List<User> selAllUsers();
    public List<User>seleUser(User user);
    public User selUserByCondition(User user);
}

业务层接口的实现类IUserServiceImpl的参考代码如下所示：

package com.aaa.service;

import com.aaa.dao.IUserDao;
import com.aaa.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
@Service("userService")
public class IUserServiceImpl implements IUserService{
    @Autowired
    private IUserDao userDao;
    public void saveUser(User user) {
        System.out.println("业务层执行增加操作");
        userDao.saveUser(user);
    }

    public void updateUser(User user) {
        System.out.println("业务层执行更新操作");
    }

    public void delUserById(Integer id) {

    }

    public List<User> selAllUsers() {
        return null;
    }

    public List<User> seleUser(User user) {
        return null;
    }

    public User selUserByCondition(User user) {
        return null;
    }
}

UserController控制层参考代码如下所示：

package com.aaa.controller;

import com.aaa.dao.IUserDao;
import com.aaa.entity.User;
import com.aaa.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

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

    public void saveUser(User user){
        userService.saveUser(user);
        System.out.println("信息页面保存成功!");
    }
}

测试类Test参考代码如下所示：

import com.aaa.controller.UserController;
import com.aaa.entity.User;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test0501 {
    @Test
    public  void test01(){
        ApplicationContext ac=new ClassPathXmlApplicationContext("spring.xml");
        UserController userController = ac.getBean("userController", UserController.class);
        userController.saveUser(new User());
    }
}