MyBatis与Spring 整合

编写Spring配置文件

<?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:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.2.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-3.2.xsd ">

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

    <!-- 数据源，使用dbcp -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
          destroy-method="close">
        <property name="driverClassName" value="${jdbc.driver}" />
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        <property name="maxActive" value="10" />
        <property name="maxIdle" value="5" />
    </bean>

    <!-- sqlSessinFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 加载mybatis的配置文件 -->
        <property name="configLocation" value="mybatis/SqlMapConfig.xml" />
        <!-- 数据源 -->
        <property name="dataSource" ref="dataSource" />
    </bean>

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 指定扫描的包名
            如果扫描多个包，每个包中间使用半角逗号分隔 -->
        <property name="basePackage" value="cn.com.sm.mapper"/>
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
    </bean>
</beans>

编写MyBatis配置文件

<?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-->
    <settings>
        <!-- 打开延迟加载的开关 -->
        <setting name="lazyLoadingEnabled" value="true"/>
        <!-- 将积极加载改为消极加载(及按需加载) -->
        <setting name="aggressiveLazyLoading" value="false"/>
        <!-- 打开全局缓存开关(二级缓存)默认值就是true -->
        <setting name="cacheEnabled" value="true"/>
        <!--执行MyBatis
        所用日志的具体实现，未指定时将指定查找-->
        <setting name="logImpl" value="LOG4J" />
    </settings>

    <!-- 别名定义 -->
    <typeAliases>
        <package name="cn.com.sm.po"/>
    </typeAliases>

    <!-- 加载映射文件 -->
    <mappers>
        <!-- 通过resource方法一次加载一个映射文件 -->
<!--        <mapper resource="sqlmap/UserMapper.xml"/>-->
        <!-- 批量加载mapper
        <package name="cn.com.sm.mapper"/>-->
    </mappers>
</configuration>

编写其他配置文件

日志配置文件"log4j.properties"：

log4j.rootLogger = debug, stdout
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = %5p [%t] - %m%n

数据库资源文件"db.properties"：

jdbc.driver=org.gjt.mm.mysql.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis_test?characterEncoding=utf-8
jdbc.username=root
jdbc.password=123456

使用Mapper代理

在pom.xml中添加：

   <build>
        <!-- 如果不添加此节点mybatis的mapper.xml文件都会被漏掉。 -->
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

在Spring全局配置文件applicationContext.xml中添加Spring的Mapper扫描器，用于扫描Mapper代理接口：

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 指定扫描的包名
            如果扫描多个包，每个包中间使用半角逗号分隔 -->
        <property name="basePackage" value="cn.com.sm.mapper"/>
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
    </bean>

由于使用了spring的扫描类，所以Mapper配置文件要和Mapper代理接口位于一个包下，且名称一样。自动扫描出来的Mapper接口的bean的id为Mapper类名（首字母小写）。

新建UserQueryMapper.xml配置文件:

<?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="cn.com.sm.mapper.UserQueryMapper">
    <select id="findUserById" parameterType="int" resultType="user">
      SELECT * FROM USER WHERE id=#{id}
    </select>
</mapper>

定义namespace下的Mapper代理接口：

package cn.com.sm.mapper;

import cn.com.sm.po.User;

public interface UserQueryMapper{
    public User findUserById(int id) throws Exception;
}

编写测试类：

package cn.com.sm.test;

import cn.com.sm.mapper.UserQueryMapper;
import cn.com.sm.po.User;
import org.junit.Before;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class UserMapperTest {
    private ApplicationContext applicationContext;

    @Before//是在执行本类所有测试方法之前先调用这个方法
    public void setup() throws Exception{
        applicationContext=new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
    }

    @Test
    public void testFindUserById() throws Exception{
        UserQueryMapper userQueryMapper=(UserQueryMapper)applicationContext.getBean("userQueryMapper");
        User user=userQueryMapper.findUserById(1);
        System.out.println(user.getId()+":"+user.getUsername());
    }
}

测试结果: