Mybatis3详解（十五）——Mybatis整合Spring框架

1、前言

       前面的十几篇文章都单独的总结了Mybatis在开发中的相关技术，但在实际开发中一般都是和Spring进行整合开发的，而Spring框架相信大家已经非常熟悉了，通过Spring的IOC/DI，能帮助我们完成对象的创建，对象之间的依赖，并且管理对象的声明周期，而Spring的AOP也能帮助我们管理对象的事务。所以下面我们来实现Mybatis和Spring的整合，并在整合后进行简单的测试。

2、创建maven项目

       ①、项目整体目录

       ②、导入依赖（双击快速复制）

        <!-- 添加Spring支持 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
        <!-- Mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>
        <!-- Mybatis-Spring -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.3</version>
        </dependency>
        <!-- Mysql驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.21</version>
        </dependency>
        <!-- Druid数据库连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.1</version>
        </dependency>
        <!-- 日志处理 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!-- 单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

3、编写实体类、Mapper接口以及Mapper.xml文件

       ①、User实体类

/**
 * 用户实体类
 */
public class User implements Serializable {
    private int userId;
    private String userName;
    private int userAge;
    private Date userBirthday;
    private int userSex;
    private String userAddress;

    //getter、setter、toString方法省略......
}

       ②、UserMapper接口

/**
 * UserMapper接口
 */
public interface UserMapper {
    //查询所有用户信息
    List<User> selectAllUser();
}

       ③、UserMapper.xml文件

<?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">
<mapper namespace="com.thr.mapper.UserMapper">

    <resultMap id="userMap" type="com.thr.pojo.User">
        <id property="userId" column="id"/>
        <result property="userName" column="username"/>
        <result property="userAge" column="age"/>
        <result property="userBirthday" column="birthday"/>
        <result property="userSex" column="sex"/>
        <result property="userAddress" column="address"/>
    </resultMap>

    <!-- 查询所有用户 -->
    <select id="selectAllUser" resultMap="userMap">
        select * from t_user
    </select>
</mapper>

5、编写数据库连接文件和日志文件

       ①、db.properties

#数据库连接配置
database.driver=com.mysql.cj.jdbc.Driver
database.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf-8
database.username=root
database.password=root

       ②、log4j.properties

log4j.rootLogger=DEBUG, Console
#Console
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=INFO
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

6、编写Mybatis全局配置文件mybatis-config.xml

       这里几乎没什么可配置的，都整合到Spring的配置文件中去了。

<?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>
        <!--开启日志-->
        <setting name="logImpl" value="STDOUT_LOGGING" />
    </settings>
</configuration>

7、编写Spring全局配置文件applicationContext.xml

       在与Spring整合之前，我们都是在Mybatis的全局配置文件中管理数据源，并且sqlSessionFactory也是我们自己通过代码来完成注入的，但是现在与Spring整合了，这些操作都要交给Spring来管理了，所以下面我们来看一下applicationContext.xml 文件中的配置：

<?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
       https://www.springframework.org/schema/context/spring-context.xsd">

    <!-- 加载classpath下的db.properties文件 -->
    <context:property-placeholder location="classpath:db.properties"/>

    <!-- 配置数据源 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${database.driver}" />
        <property name="url" value="${database.url}" />
        <property name="username" value="${database.username}" />
        <property name="password" value="${database.password}" />
    </bean>

    <!-- 配置sqlSessionFactory，SqlSessionFactoryBean是用来产生sqlSessionFactory的 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 加载上面配置好数据源 -->
        <property name="dataSource" ref="dataSource" />
        <!-- 加载mybatis的映射配置文件;XxxMapper.xml -->
        <property name="mapperLocations" value="classpath:com/thr/mapper/*.xml" />
        <!-- 加载mybatis的全局配置文件;mybatis-config.xml-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <!-- 配置别名，使用包扫描,扫描com.thr.pojo包下的所有实体 -->
        <property name="typeAliasesPackage" value="com.thr.pojo"/>
    </bean>

    <!-- 创建UserMapper接口的代理对象,这里是创建单个代理对象，不推荐这种方式，如果多个类就麻烦了
    这里的org.mybatis.spring.mapper.MapperFactoryBean<T>类就是用来创建 Mapper代理对象的类 -->
    <!--
    <bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="mapperInterface" value="com.thr.mapper.UserMapper"/>
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>
    </bean>
    -->

    <!-- 加载所在包名下的Mapper接口，并且为其创建代理对象，推荐 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.thr.mapper" />
        <!-- 可选，如果不写，Spring启动时候。容器中自动会按照类型去把SqlSessionFactory对象注入进来 -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
    </bean>
</beans>

8、编写测试代码与运行结果

       ①、测试代码

package com.thr.test;

import com.thr.mapper.UserMapper;
import com.thr.pojo.User;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.List;

public class UserMapperTest {
    //创建ApplicationContext容器
    private ApplicationContext applicationContext = null;

    @Before
    public void getApplicationContext() throws Exception {
        //获取Spring容器
        applicationContext = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
    }
    //查询所有用户
    @Test
    public void testSelectAllUser(){
        //获取UserMapper对象
        UserMapper userMapper = applicationContext.getBean("userMapper", UserMapper.class);
        List<User> users = userMapper.selectAllUser();
        for (User user : users) {
            System.out.println(user);
        }
    }
}

       ②、运行结果