MyBatis原理，Spring、SpringBoot整合MyBatis

1. MyBatis概述

MyBatis 是支持定制化 SQL、存储过程以及高级映射的优秀的持久层框架。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以对配置和原生Map使用简单的 XML 或注解，将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java对象)映射成数据库中的记录。

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2. MyBatis原理

简述MyBatis的原理

Mybatis——工作原理
实现了对Mapper接口对动态代理

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对于SqlSessionTemplate的理解：（线程安全的实现类）
MyBatis-Spring(二)--SqlSessionTemplate实现增删改查：

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3. Spring整合Mybatis

配置文件结构

1）pom.xml 依赖

<!-- 版本号 -->
<properties>
        <servlet-version>3.0.1</servlet-version>
        <jsp-version>2.2</jsp-version>
        <jstl-version>1.2</jstl-version>
        <spring-version>4.1.6.RELEASE</spring-version>
        <aspectjweaver-version>1.8.6</aspectjweaver-version>
        <mybatis-version>3.5.0</mybatis-version>
        <mybatis-spring-version>2.0.0</mybatis-spring-version>
        <log4j-version>1.2.17</log4j-version>
        <mysql-connector-java-version>5.1.38</mysql-connector-java-version>
        <jackson-version>2.8.5</jackson-version>
        <commons-fileupload-version>1.3.1</commons-fileupload-version>
        <poi-version>3.17</poi-version>
        <hutool-version>4.5.9</hutool-version>
        <version.shiro>1.2.2</version.shiro>
        <gson-version>2.8.2</gson-version>
</properties>
<!-- 依赖 -->
<dependencies>
<!-- spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring-version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring-version}</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>${aspectjweaver-version}</version>
        </dependency>
        <!-- mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>${mybatis-version}</version>
        </dependency>
        <!-- mybatis和spring整合 -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>${mybatis-spring-version}</version>
        </dependency>
        <!-- log4j 日志 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j-version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-nop</artifactId>
            <version>1.7.2</version>
        </dependency>
        <!-- commons-logging -->
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.1.3</version>
        </dependency>
        <!-- mysql 驱动类 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql-connector-java-version}</version>
        </dependency>
</dependencies>

2）web.xml SpringMVC控制器

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
	http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <!-- 上下文参数 spring配置文件 -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            classpath:spring/spring-aop.xml,
            classpath:spring/spring*.xml,
        </param-value>
    </context-param>
    <!-- 字符编码过滤器 -->
    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <!-- 监听器-->
    <listener>
        <!--  加载Spring默认配置文件  -->
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <!-- SpringMVC前端控制器 -->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>
                classpath:spring/springmvc.xml
            </param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <!--welcome-file-list>
        <welcome-file>admin-user-password.html</welcome-file>
    </welcome-file-list-->

</web-app>

3）spring-mybatis.xml 整合

<?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">

    <!-- 加载属性文件 -->
    <context:property-placeholder location="classpath:myDB/db.properties"/>
    <!-- 数据源 -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driver}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>
    <!-- SqlSessionFactory -->
    <bean id="factory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="typeAliasesPackage" value="neau.cekong.pojo"></property>
        <property name="configLocation" value="classpath:myDB/mybatis-config.xml"></property>
    </bean>
    <!-- 扫描器 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="neau.cekong.mapper"></property>
        <property name="sqlSessionFactoryBeanName" value="factory"></property>
    </bean>

</beans>

4）spring-aop.xml 声明式事务

<?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:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx" 
	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/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd" default-autowire="byName">
    <!-- 注解扫描 -->
    <context:component-scan base-package="neau.cekong.**"></context:component-scan>
	<!-- 代理方式 -->
	<aop:aspectj-autoproxy proxy-target-class="true"></aop:aspectj-autoproxy>

    <!-- 事务管理器 -->
    <bean id="txManage" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    	<property name="dataSource" ref="dataSource"></property>
    </bean>
    <!-- 声明式事务 -->
    <tx:advice id="txAdvice" transaction-manager="txManage">
    	<tx:attributes>
    		<tx:method name="ins*"/><tx:method name="add*"/>
    		<tx:method name="del*"/>
    		<tx:method name="upd*"/><tx:method name="alt*"/>
    		<tx:method name="*" read-only="true"/>
    	</tx:attributes>
    </tx:advice>
    <!-- 配置aop -->
    <aop:config>
    	<aop:pointcut expression="execution(* neau.cekong.service.impl.*.*(..))" id="mypoint"/>
    	<aop:advisor advice-ref="txAdvice" pointcut-ref="mypoint"/>
    </aop:config>
</beans>

5）spring-mvc.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:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       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://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!-- 扫描注解 -->
    <context:component-scan base-package="neau.cekong.controller"></context:component-scan>
    <aop:aspectj-autoproxy proxy-target-class="true"/>
    <!-- 注解驱动 -->
    <mvc:annotation-driven></mvc:annotation-driven>
    <!-- 静态资源 -->
    <mvc:default-servlet-handler />
    <mvc:resources location="/js/" mapping="/js/**"></mvc:resources>
</beans>

6）log4j.properties

log4j.rootCategory=ERROR, CONSOLE ,LOGFILE

log4j.logger.neau.cekong.mapper=DEBUG

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%C %d{YYYY-MM-dd hh:mm:ss}  %m %n

log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=E:/my.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%m %n

7）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>
    <!-- 开启驼峰映射 ，为自定义的SQL语句服务-->
    <!--设置启用数据库字段下划线映射到java对象的驼峰式命名属性，默认为false-->
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="false"/>
    </settings>

</configuration>

8）db.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/FarmlandMonitor?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull
jdbc.username=root
jdbc.password=root

#注意更改包名！！！#

参考文章: springmvc+mybatis的两种配置和应用方式

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4. Spring-Boot整合Mybatis

数据库在开发过程中充当着重要的角色，框架的出现抹去了以往JDBC操作数据库的纷繁。传统的JDBC的数据库操作步骤为：①加载驱动 ②创建数据库连接 ③创建statement对象 ④执行SQL获取数据 ⑤数据转换 ⑥资源释放。而Mybatis关注第④步。于是在如此流行的后台框架Spring boot集成Mybatis也是大势所趋了。

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1）Mybatis的集成可以简单地概括成两步：

①application.properties增加spring配置数据库链接地址

②pom.xml引入mybatis-spring-boot-starter和mysql-connector-java

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spring boot+mybatis整合（使用配置好的启动器）
【SpringBoot2.0系列05】SpringBoot之整合Mybatis
springboot整合mybatis（步骤流畅）
mybatis最全教程之springboot集成mybatis（简洁）
Spring Boot（三）Spring Boot 和 MyBatis 整合（使用application.properties而不是yml）
SpringBoot 和 Mybatis 整合（腾讯云社区 清晰明了）
spring-boot 框架整合 MyBatis（简洁明了 结构清晰）

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SpringBoot+Mybatis(JavaConfig方式配置)
springboot整合mybatis(SSM开发环境搭建 2种方式)

2）使用Config.java配置（传统方式）

1_ 项目结构

2_ db.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/FarmlandMonitor?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull
jdbc.username=root
jdbc.password=root

3_ DataSourceConfiguration.java

package neau.cekong.weather.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.jdbc.datasource.DriverManagerDataSource;

@Configuration
//这个注解导入刚才增加的jdbc配置文件
@PropertySource("classpath:db.properties")
public class DataSourceConfiguration {
    @Value("${jdbc.driver}")
    private String driver;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String username;
    @Value("${jdbc.password}")
    private String password;


    @Bean
    public DriverManagerDataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(driver);
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);

        return dataSource;
    }
}

4_ MyBatisConfig.java

package neau.cekong.weather.config;

import javax.sql.DataSource;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.transaction.annotation.TransactionManagementConfigurer;


@Configuration
//加上这个注解，使得支持事务
@EnableTransactionManagement
public class MyBatisConfig implements TransactionManagementConfigurer {
    @Autowired
    private DataSource dataSource;

    @Override
    public PlatformTransactionManager annotationDrivenTransactionManager() {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "mySqlSessionFactory")
    public SqlSessionFactory sqlSessionFactoryBean() {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setTypeAliasesPackage("neau.cekong.pojo");

        try {
            return bean.getObject();
        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }

    @Bean
    public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

5_ MyBatisMapperScannerConfig.java

package neau.cekong.weather.config;

import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 扫描mybatis的接口
 */
@Configuration
// 因为这个对象的扫描，需要在MyBatisConfig的后面注入，所以加上下面的注解
@AutoConfigureAfter(MyBatisConfig.class)
public class MyBatisMapperScannerConfig {
    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer() {
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        //获取之前注入的beanName为sqlSessionFactory的对象
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("mySqlSessionFactory");
        //指定xml配置文件的路径
        mapperScannerConfigurer.setBasePackage("neau.cekong.weather.mapper");
        return mapperScannerConfigurer;
    }
}

参考文章： https://www.cnblogs.com/zhuxiaojie/p/5836159.html#4278741