spring与mybatis的使用

1、spring与mybatis整合配置文件版

spring与mybaits整合需要一个中间包mybatis-spring，将mybatis交给spring管理，中间包pom依赖如下

<dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.3</version>
    </dependency>

完整pom依赖如下

<dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>

    <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.1.10</version>
    </dependency>

    <!--spring-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>


    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-beans</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>

    <!--mybatis-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.3</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>1.9.5</version>
    </dependency>


    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.3</version>
    </dependency>


    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.37</version>
      <scope>runtime</scope>
    </dependency>

  </dependencies>　　

spring的application配置

<?<xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" 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:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
       xmlns:cache="http://www.springframework.org/schema/cache"
       xsi:schemaLocation="
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd
    http://www.springframework.org/schema/jdbc
    http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd
    http://www.springframework.org/schema/cache
    http://www.springframework.org/schema/cache/spring-cache-3.1.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/util
    http://www.springframework.org/schema/util/spring-util.xsd">
    <!-- @Service,@Component,@Repository,@Controller 默认 false使用自定义规则-->
    <!-- 引入jdbc配置文件 -->
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:jdbc.properties</value>
            </list>
        </property>
    </bean>

    <context:component-scan base-package="com.wonders.bigdata" use-default-filters="false">

        <context:include-filter type="annotation" expression="org.springframework.stereotype.Service"/>

    </context:component-scan>

    <!-- dataSource 配置 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
        <!-- 基本属性 url、user、password -->
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        <property name="driverClassName" value="${jdbc.driverClass}"/>

        <!-- 配置初始化大小、最小、最大 -->
        <property name="initialSize" value="1" />
        <property name="minIdle" value="1" />
        <property name="maxActive" value="20" />

        <!-- 配置获取连接等待超时的时间 -->
        <property name="maxWait" value="60000" />

        <!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->
        <property name="timeBetweenEvictionRunsMillis" value="60000" />

        <!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->
        <property name="minEvictableIdleTimeMillis" value="300000" />

        <property name="validationQuery" value="SELECT ‘x‘" />
        <property name="testWhileIdle" value="true" />
        <property name="testOnBorrow" value="false" />
        <property name="testOnReturn" value="false" />

        <!-- 打开PSCache，并且指定每个连接上PSCache的大小 -->
        <property name="poolPreparedStatements" value="false" />
        <property name="maxPoolPreparedStatementPerConnectionSize" value="20" />

        <!-- 配置监控统计拦截的filters -->
        <property name="filters" value="stat" />
    </bean>

    <!-- mybatis文件配置，扫描所有mapper文件 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean" p:dataSource-ref="dataSource" p:configLocation="classpath:mybatis-config.xml" />

    <!-- spring与mybatis整合配置，扫描所有dao -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer" p:basePackage="com.wonders.bigdata.mapper" p:sqlSessionFactoryBeanName="sqlSessionFactory" />

    <!-- 对dataSource 数据源进行事务管理 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" p:dataSource-ref="dataSource" />

    <!-- 配置使Spring采用CGLIB代理 -->
    <aop:aspectj-autoproxy proxy-target-class="true" />

    <!-- 启用对事务注解的支持 -->
    <tx:annotation-driven transaction-manager="transactionManager" />


</beans>

mybatis config配置

<?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="com.wonders.bigdata.domain"/>
    </typeAliases>

    <!-- 配置映射文件：用来配置sql语句和结果集类型等 -->
    <mappers>
        <mapper resource="WebsitesMapper.xml"/>
    </mappers>


</configuration>　

之后需要对实体对应的mapper文件进行编写，有xml或者注解的方式进行定义，mapper文件如下。

package com.wonders.bigdata.mapper;

import com.wonders.bigdata.domain.Websites;
import com.wonders.bigdata.domain.WebsitesExample;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface WebsitesMapper {
    int countByExample(WebsitesExample example);

    int deleteByExample(WebsitesExample example);

    int deleteByPrimaryKey(Long id);

    int insert(Websites record);

    int insertSelective(Websites record);

    List<Websites> selectByExample(WebsitesExample example);

    Websites selectByPrimaryKey(Long id);

    int updateByExampleSelective(@Param("record") Websites record, @Param("example") WebsitesExample example);

    int updateByExample(@Param("record") Websites record, @Param("example") WebsitesExample example);

    int updateByPrimaryKeySelective(Websites record);

    int updateByPrimaryKey(Websites record);

    @Select("select * from bd_websites where id = #{id}")
    Websites findById(Long id);
}　　

对应service编写

package com.wonders.bigdata.spring.service;

import com.wonders.bigdata.domain.Websites;

public interface WebsitesService {

    Websites findById(Long id);
}

package com.wonders.bigdata.spring.service.impl;

import com.wonders.bigdata.domain.Websites;
import com.wonders.bigdata.mapper.WebsitesMapper;
import com.wonders.bigdata.spring.service.WebsitesService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class WebsitesServiceImpl implements WebsitesService {

    @Autowired
    private WebsitesMapper websitesMapper;

    @Override
    public Websites findById(Long id) {
        return websitesMapper.findById(id);
    }
}　　

测试

@Test
    public void springContext() {
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:application-context.xml");
        MessageService messageService = context.getBean(MessageService.class);
        WebsitesService websitesService = context.getBean(WebsitesService.class);
        System.out.println(messageService.getMessage());

        System.out.println(websitesService.findById(1L));


    }

2、mybatis-spring整合原理

mybatis主要是通过使用sping的ImportBeanDefinitionRegistrar接口来将其交给spring管理，其中实现了ImportBeanDefinitionRegistrar接口的类将会拥有注册bean的能力，而其中对应bean对象的创建是通过实现FactoryBean接口来管理

MapperScannerRegistrar源码

public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        AnnotationAttributes mapperScanAttrs = AnnotationAttributes.fromMap(importingClassMetadata.getAnnotationAttributes(MapperScan.class.getName()));
        if (mapperScanAttrs != null) {
            this.registerBeanDefinitions(mapperScanAttrs, registry, generateBaseBeanName(importingClassMetadata, 0));
        }

    }

void registerBeanDefinitions(AnnotationAttributes annoAttrs, BeanDefinitionRegistry registry, String beanName) {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MapperScannerConfigurer.class);
        builder.addPropertyValue("processPropertyPlaceHolders", true);
        Class<? extends Annotation> annotationClass = annoAttrs.getClass("annotationClass");
        if (!Annotation.class.equals(annotationClass)) {
            builder.addPropertyValue("annotationClass", annotationClass);
        }

        Class<?> markerInterface = annoAttrs.getClass("markerInterface");
        if (!Class.class.equals(markerInterface)) {
            builder.addPropertyValue("markerInterface", markerInterface);
        }

        Class<? extends BeanNameGenerator> generatorClass = annoAttrs.getClass("nameGenerator");
        if (!BeanNameGenerator.class.equals(generatorClass)) {
            builder.addPropertyValue("nameGenerator", BeanUtils.instantiateClass(generatorClass));
        }

        Class<? extends MapperFactoryBean> mapperFactoryBeanClass = annoAttrs.getClass("factoryBean");
        if (!MapperFactoryBean.class.equals(mapperFactoryBeanClass)) {
            builder.addPropertyValue("mapperFactoryBeanClass", mapperFactoryBeanClass);
        }

        String sqlSessionTemplateRef = annoAttrs.getString("sqlSessionTemplateRef");
        if (StringUtils.hasText(sqlSessionTemplateRef)) {
            builder.addPropertyValue("sqlSessionTemplateBeanName", annoAttrs.getString("sqlSessionTemplateRef"));
        }

        String sqlSessionFactoryRef = annoAttrs.getString("sqlSessionFactoryRef");
        if (StringUtils.hasText(sqlSessionFactoryRef)) {
            builder.addPropertyValue("sqlSessionFactoryBeanName", annoAttrs.getString("sqlSessionFactoryRef"));
        }

        List<String> basePackages = new ArrayList();
        basePackages.addAll((Collection)Arrays.stream(annoAttrs.getStringArray("value")).filter(StringUtils::hasText).collect(Collectors.toList()));
        basePackages.addAll((Collection)Arrays.stream(annoAttrs.getStringArray("basePackages")).filter(StringUtils::hasText).collect(Collectors.toList()));
        basePackages.addAll((Collection)Arrays.stream(annoAttrs.getClassArray("basePackageClasses")).map(ClassUtils::getPackageName).collect(Collectors.toList()));
        String lazyInitialization = annoAttrs.getString("lazyInitialization");
        if (StringUtils.hasText(lazyInitialization)) {
            builder.addPropertyValue("lazyInitialization", lazyInitialization);
        }

        builder.addPropertyValue("basePackage", StringUtils.collectionToCommaDelimitedString(basePackages));
        registry.registerBeanDefinition(beanName, builder.getBeanDefinition());
    }

根据扫描的mapper名称对bean进行注册

registry.registerBeanDefinition(beanName, builder.getBeanDefinition());