Spring学习（五）Spring和Mybatis的整合

2024-01-09 14:19:46

1、前言

在整合之前、要搞清楚是谁整合谁、后续会学到很多整合的例子。在这里、是Spring整合Mybatis、Spring中集成了很多关于Mybatis中一些关键类的jar包、通过这些、可以更加方便的联系Mybatis和数据库之间的关系。以前、Mybatis操作数据库的思路是这样的SqlSessionFactory -> SqlSession ->StudentMapper ->CRUD。可以发现 ，MyBatis最终是通过SqlSessionFactory来操作数据库。Spring整合MyBatis 其实就是将MyBatis的SqlSessionFactory 交给Spring

2、项目骨架

3、步骤

1、下载相关的jar包

点击我下载

2、创建实体类和表

3、配置MyBatis配置文件conf.xml

其实里面没用到啥东西、单纯需要配一下。

<?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>

    <!--   数据库信息  -->
    <!--  加载映射文件  -->
<!--    <mappers>-->
<!--        <mapper resource="com/feng/mapper/studentMapper.xml"></mapper>-->
<!--    </mappers>-->
</configuration>

4、通过mapper.xml将类、表建立映射关系

studentMapper

package com.feng.mapper;

import com.feng.enetity.Student;

public interface StudentMapper {
    public void addStudent(Student student);
}

studentMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<!--namespace：该mapper.xml映射文件的唯一标识-->
<mapper namespace="com.feng.mapper.StudentMapper">

    <select id="queryStudentByStuNo" parameterType="int" resultType="com.feng.enetity.Student">
        select * from student where stuno = #{stuNo}
    </select>
    
    <insert id="addStudent" parameterType="com.feng.enetity.Student">
        insert into student(stuno, stuname, stuage) values(#{stuNo},#{stuName},#{stuAge})
    </insert>
</mapper>

5、Spring管理SqlSessionFactory

之前使用MyBatis: conf.xml ->SqlSessionFacotry .现在整合的时候，需要通过Spring管理SqlSessionFacotry ，因此产生qlSessionFacotry 所需要的数据库信息不在放入conf.xml,而需要放入spring配置文件中配置Spring配置文件（applicationContext.xml）.
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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!-- 加载db.properties文件 -->
    <bean id="config" class="org.springframework.beans.factory.config.PreferencesPlaceholderConfigurer">
        <property name="locations">
            <array>
                <value>classpath:db.properties</value>
            </array>
        </property>
    </bean>

    <!--    配置数据库信息（替代mybatis的conf.xml）    -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="${driver}"></property>
        <property name="url" value="${url}"></property>
        <property name="username" value="${username}"></property>
        <property name="password" value="${password}"></property>
    </bean>

    <!--  在SpringIoc容器中创建Mybatis核心类SqlSessionFactory  -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <!-- 加载Mybatis配置文件 -->
        <property name="configLocation" value="classpath:conf.xml"></property>
        <!-- 加载mapper.xml路径 -->
        <property name="mapperLocations" value="com/feng/mapper/*.xml"></property>
    </bean>

    <bean id="studentMapper" class="com.feng.dao.impl.StudentDaoImpl">
        <!--将Spring配置的sqlSessionFactory 对象交给mapper(dao)-->
        <property name="sqlSessionFactory" ref="sqlSessionFactory"></property>
    </bean>
    <bean id="studentService" class="com.feng.service.impl.StudentServiceImpl">
        <property name="studentMapper" ref="studentMapper"></property>
    </bean>

</beans>

6、使用Spring-Mybatis整合产物开发程序

目标：通过sprin*生mybatis最终操作需要的动态mapper对象(StudentMapper对象)、Sprin*生动态mapper对象有3种方法：
a.第一种方式
DAO层实现类继承 SqlSessionDaoSupport类SqlSessionDaoSupport类提供了一个属性 SqlSession
b.第二种方式
就是省略掉第一种方式的实现类、直接MyBatis提供的 Mapper实现类：org.mybatis.spring.mapper.MapperFactoryBean 。缺点：每个mapper都需要一个配置一次
c.第三种方式
批量配置实现类
注：本文用的是第一种方式。

7、三层架构实现

1、Dao层

StudentDaoImpl

package com.feng.dao.impl;

import com.feng.mapper.StudentMapper;
import com.feng.enetity.Student;
import org.apache.ibatis.session.SqlSession;
import org.mybatis.spring.support.SqlSessionDaoSupport;

public class StudentDaoImpl extends SqlSessionDaoSupport implements StudentMapper {
    @Override
    public void addStudent(Student student) {
        SqlSession session = super.getSqlSession();
        StudentMapper stuDao = session.getMapper(StudentMapper.class);
        stuDao.addStudent(student);
    }
}

2、Service层

1、接口IStudentService

package com.feng.service;

import com.feng.enetity.Student;

public interface IStudentService {
    public void addStudent(Student student);
}

2、实现类StudentServiceImpl

package com.feng.service.impl;

import com.feng.enetity.Student;
import com.feng.mapper.StudentMapper;
import com.feng.service.IStudentService;

public class StudentServiceImpl implements IStudentService {
    private StudentMapper studentMapper;

    public void setStudentMapper(StudentMapper studentMapper) {
        this.studentMapper = studentMapper;
    }

    @Override
    public void addStudent(Student student) {
        // 调用Dao
        studentMapper.addStudent(student);
    }
}

3、数据库配置db.properties

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/xiao?serverTimezone=GMT%2B8
username=root
password=123456

4、测试

1、Test

package com.feng.test;

import com.feng.enetity.Student;
import com.feng.service.IStudentService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        IStudentService studentService = (IStudentService)context.getBean("studentService");
        Student student = new Student();
        student.setStuNo(4);
        student.setStuAge(81);
        student.setStuName("xiaofeng1");
        studentService.addStudent(student);
    }
}

5、总结

借助Spring相关的jar包、极大的简化了Mybatis的操作、为后续的开发简便了很多步骤。

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