Spring框架和Mybatis框架工作原理

        Spring框架是一个轻量级的容器，用于管理业务相关对象的。核心功能主要为IOC，AOP，MVC。

• IOC：控制反转，将对象的创建过程交给容器，让容器管理对象的生命周期如创建，初始化，销毁等。
• AOP：面向切面编程，对关注点进行模块化，通过对某一功能点进行编程，在AOP的实现过程中，有静态代理和动态代理两种方式。
• MVC：Spring MVC,Spring提供的基于mvc模式设计的web框架

        Mybatis框架不完全是一个ORM框架，是一个基于Java的持久层框架，Mybatis框架需要程序员自己编写Sql语句，不过mybatis可以通过注解或XML方式灵活配置要运行的Sql语句，并将Java对象和Sql语句映射生成最终执行的Sql，最后将sql执行的结果再映射生成Java对象。

        这次我们通过一个案例，且用注解方式来深刻了解一下这两个框架的工作原理：

• 首先创建pojo包的User类

package pojo;

import org.springframework.stereotype.Component;

@Component("user")
public class User {

    private Integer id;
    private String name;
    private String password;
    private Integer age;
    private String email;
    private String telephone;

    public User() {
    }

    public User(Integer id, String name, String password, Integer age, String email, String telephone) {
        this.id = id;
        this.name = name;
        this.password = password;
        this.age = age;
        this.email = email;
        this.telephone = telephone;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

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

• 创建mapper包的UserMapper类

package mapper;

import java.util.List;
import org.apache.ibatis.annotations.*;
import org.springframework.stereotype.Repository;
import pojo.User;

@Repository("userMapper")
@Mapper
public interface UserMapper {

    @Select("select * from user where email = #{email} and password = #{password}")
    User login(@Param("email")String email,@Param("password")String password);

    @Select("select * from User")
    List<User> queryList();

    @Select("select * from User where id = #{id}")
    User queryById(Integer id);

    @Update("update User set name = #{name} ,password = #{password},age = #{age},email = #{email} where id = #{id}")
    boolean updateByPrimaryKey(User bean);

    @Insert("insert into User (name,password,age,email,telephone) values(#{name},#{password},#{age},#{email},#{telephone})")
    User add(User bean);
}

• 创建service包的UserService类

package service;

import org.apache.ibatis.annotations.Param;
import pojo.User;
import java.util.List;

public interface UserService {

    List<User> queryList();

    User queryById(Integer id);

    boolean updateByPrimaryKey(User bean);

    User login(@Param("email")String email,@Param("password")String password);

    User add(User bean);
}

• 创建service.impl包的UserServiceImpl类

package service.impl;

import mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import pojo.User;
import service.UserService;
import java.util.List;

@Service("userService")
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public List<User> queryList() {
        return userMapper.queryList();
    }

    @Override
    public User queryById(Integer id) {
        return userMapper.queryById(id);
    }

    @Override
    public boolean updateByPrimaryKey(User bean) {
        return userMapper.updateByPrimaryKey(bean);
    }

    @Override
    public User login(String email, String password) {
        return userMapper.login(email, password);
    }

    @Override
    public User add(User bean) {
        return userMapper.add(bean);
    }
}

• jdbc.properties

driver=com.mysql.cj.jdbc.Driver<!--mysql 8.0以上版本才需要加cj-->
url=jdbc:mysql://localhost:port/DatabaseName?serverTimezone=UTC
user=用户
password=密码

• applicationContext.xml

<?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"
       xmlns:mybatis="http://mybatis.org/schema/mybatis-spring"
       xmlns:aop="http://www.springframework.org/schema/aop"
       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
                           http://mybatis.org/schema/mybatis-spring
                           http://mybatis.org/schema/mybatis-spring.xsd
                           http://www.springframework.org/schema/aop
                           https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!-- 支持注解 -->
    <context:annotation-config/>

    <context:component-scan base-package="controller"/>

    <context:property-placeholder location="classpath:jdbc.properties" />

    <!-- 数据库信息 -->
    <bean  id = "dataSource" class = "org.springframework.jdbc.datasource.DriverManagerDataSource">

        <property name="driverClassName" value="${driver}"/>

        <property name="url" value="${url}"/>

        <property name="username" value="root"/>

        <property name="password" value="${password}"/>

    </bean>
    
    <aop:config>

        <aop:pointcut id="pcUuser" expression="execution(* cn.edu.lingnan.service.impl.*.*(..))"/>

    </aop:config>

    <!-- define the SqlSessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">

        <property name="dataSource" ref="dataSource" />

        <property name="configLocation" value="mybatis-config.xml" />

    </bean>

    <mybatis:scan base-package="mapper"/>

</beans>

• mybatis-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <setting name="logImpl" value="STDOUT_LOGGING" />
    </settings>

    <typeAliases>
        <package name="pojo"/>
    </typeAliases>

    <mappers>
        <package name="mapper"/>
    </mappers>
</configuration>

• 创建测试类AppTest类

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import pojo.User;
import service.UserService;
import java.util.List;

public class AppTest {
    @Test
    public void test1(){

            ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");

            UserService userService = ctx.getBean("userService", UserService.class);

            List<User> bean = userService.queryList();

            System.out.println(bean);
    }
}