mybatis与spring的整合之SqlSessionFactoryBean

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SqlSessionFactoryBean配置

解释： MapperFactoryBean是将映射接口 注册进spring，详见 mybatis与spring的整合之MapperFactoryBean，而 SqlSessionFactoryBean则是 解析映射接口对应的sql配置文件（xml文件）
SqlSessionFactoryBean配置

在基本的 MyBatis 中，session 工厂可以使用 SqlSessionFactoryBuilder 来创建。而在 MyBatis-Spring 中,则使用 SqlSessionFactoryBean 来替代。
SqlSessionFactoryBean引入sql配置文件有两种形式

注入mapperLocations

sql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="com.xxl.job.admin.dao.XxlJobGroupDao">

<sql id="Base_Column_List">
t.id,
t.app_name,
t.title,
t.`order`,
t.address_type,
t.address_list
</sql>

<select id="findAll" resultMap="XxlJobGroup">
SELECT <include refid="Base_Column_List" />
FROM XXL_JOB_QRTZ_TRIGGER_GROUP AS t
ORDER BY t.order ASC
</select>

</mapper>

引入

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="mapperLocations" value="classpath:mybatis-mapper/*.xml"/>
</bean>

Resource[] mapperLocations
spring内置的属性编辑器会将mybatis-mapper/*.xml转换为Resource数组

注入configLocation

configuration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>
<setting name="" value=""/>
</settings>*/
<!--引入映射文件-->
<mappers>
<mapper resource="mybatis-mapper/XxlJobGroupMapper.xml" />
<mapper resource="mybatis-mapper/XxlJobInfoMapper.xml" />
<mapper resource="mybatis-mapper/XxlJobLogGlueMapper.xml" />
<mapper resource="mybatis-mapper/XxlJobLogMapper.xml" />
<mapper resource="mybatis-mapper/XxlJobRegistryMapper.xml" />
</mappers>
</configuration>

 

引入

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<!--<property name="mapperLocations" value="classpath:mybatis-mapper/*.xml"/>-->
<property name="configLocation" value="classpath:mybatis-configuration/config.xml"/>
</bean>

mapperLocations与configLocation比较

mapperLocations仅仅是sql配置文件，会被解析放入Configuration中
configLocation可以设置其他东西，比如二级缓存、实体类别名、数据源（DataSource）等，可以配置多个config.xml实现多数据源配置。它会被解析为Configuration对象，这是构建SqlSessionFactory所必须的。
MyBatis 的配置文件包含了会深深影响 MyBatis 行为的设置和属性信息，这里可直接看官网：configuration配置

SqlSessionFactoryBean源码跟踪

实现了FactoryBean接口

SqlSessionFactoryBean实现了FactoryBean，重写了getObject接口 ，通过该方法返回SqlSessionFactory对象

public SqlSessionFactory getObject() throws Exception {
if (this.sqlSessionFactory == null) {
afterPropertiesSet();
}
return this.sqlSessionFactory;
}

实现了InitializingBean接口

SqlSessionFactoryBean实现了InitializingBean接口，重写了afterPropertiesSet方法

public void afterPropertiesSet() throws Exception {
notNull(dataSource, "Property 'dataSource' is required");
notNull(sqlSessionFactoryBuilder, "Property 'sqlSessionFactoryBuilder' is required");
state((configuration == null && configLocation == null) || !(configuration != null && configLocation != null),
"Property 'configuration' and 'configLocation' can not specified with together");

this.sqlSessionFactory = buildSqlSessionFactory();
}

dataSource不能为空

dataSource必须手动显示注入

sqlSessionFactoryBuilder不能为空

sqlSessionFactoryBuilder初始化为SqlSessionFactoryBuilder，可不用手动注入

configuration与configLocation

configuration是bean，configLocation是配置文件，两者不能同时配置

关键方法buildSqlSessionFactory

构建Configuration对象

通过自定义的configuration，一个bean
通过自定义的configLocation，一个xml配置文件
以上都没有的话，则new一个configuration对象

Configuration configuration;
XMLConfigBuilder xmlConfigBuilder = null;
if (this.configuration != null) {
configuration = this.configuration;
if (configuration.getVariables() == null) {
configuration.setVariables(this.configurationProperties);
} else if (this.configurationProperties != null) {
configuration.getVariables().putAll(this.configurationProperties);
}
} else if (this.configLocation != null) {
xmlConfigBuilder = new XMLConfigBuilder(this.configLocation.getInputStream(), null, this.configurationProperties);
configuration = xmlConfigBuilder.getConfiguration();
} else {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Property 'configuration' or 'configLocation' not specified, using default MyBatis Configuration");
}
configuration = new Configuration();
if (this.configurationProperties != null) {
configuration.setVariables(this.configurationProperties);
}
}

设置数据源dataSource

configuration.setEnvironment(new Environment(this.environment, this.transactionFactory, this.dataSource));
解析configLocation

if (xmlConfigBuilder != null) {
try {
xmlConfigBuilder.parse();
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Parsed configuration file: '" + this.configLocation + "'");
}
} catch (Exception ex) {
throw new NestedIOException("Failed to parse config resource: " + this.configLocation, ex);
} finally {
ErrorContext.instance().reset();
}
}

如果configLocation属性值不为空，则xmlConfigBuilder会通过configLocation对象构建，这里就会开始解析

XMLConfigBuilder.parse解析配置文件

从根目录configuration开始解析，后面就不具体看了

public Configuration parse() {
if (parsed) {
throw new BuilderException("Each XMLConfigBuilder can only be used once.");
}
parsed = true;
parseConfiguration(parser.evalNode("/configuration"));
return configuration;
}

解析mapperLocations

如果mapperLocations属性值不为空，则在这里开始解析

if (!isEmpty(this.mapperLocations)) {
for (Resource mapperLocation : this.mapperLocations) {
if (mapperLocation == null) {
continue;
}

try {
XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(mapperLocation.getInputStream(),
configuration, mapperLocation.toString(), configuration.getSqlFragments());
xmlMapperBuilder.parse();
} catch (Exception e) {
throw new NestedIOException("Failed to parse mapping resource: '" + mapperLocation + "'", e);
} finally {
ErrorContext.instance().reset();
}
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Parsed mapper file: '" + mapperLocation + "'");
}
}
}

XMLMapperBuilder.parse解析sql配置

从根目录mapper开始解析，后面就不具体看了

public void parse() {
if (!configuration.isResourceLoaded(resource)) {
configurationElement(parser.evalNode("/mapper"));
configuration.addLoadedResource(resource);
bindMapperForNamespace();
}
// 解析ResultMap
parsePendingResultMaps();
// 二级缓存
parsePendingCacheRefs();
// sql语句
parsePendingStatements();
}

设置其他属性

SqlSessionFactory可以注入一些其他属性，比如缓存、别名等，有的话都会被设置进configuration对象中

构建SqlSessionFactory对象

return this.sqlSessionFactoryBuilder.build(configuration);
SqlSessionFactoryBuilder.build，构建的是DefaultSqlSessionFactory

public SqlSessionFactory build(Configuration config) {
return new DefaultSqlSessionFactory(config);
}

 参考文档： https://blog.csdn.net/yu_kang/article/details/88929606