spring-mybatis与原生mybatis使用对比分析

2023-09-20 19:24:05 226

原生mybatis使用方法：

Stringresource="mybatis-config.xml";
InputStreaminputStream=Resources.getResourceAsStream(resource);
SqlSessionFactorysqlSessionFactory=newSqlSessionFactoryBuilder().build(inputStream);
SqlSessionsession=sqlSessionFactory.openSession();
try{
Employeeemployee=newEmployee(null,"doubi","1","ddd@sys.com");
EmployeeMappermapper=session.getMapper(EmployeeMapper.class);
mapper.addEmp(employee);
session.commit();
}finally{
session.close();
}

spring使用方法，直接注入即可

@Autowired
EmployeeMapperemployeeMapper

那么spring为我们做了什么？下面研究一下mybatis-spring.jar这个jar包

首先来看一下如何使用spring整合mybatis，下面是使用spring-mybatis的四种方法：

方法一：（使用MapperFactoryBean）

这样做的缺点是每一个mapper接口都要在xml里配置一下

方法二：采用接口org.apache.ibatis.session.SqlSession的实现类org.mybatis.spring.SqlSessionTemplate

mybatis中,sessionFactory可由SqlSessionFactoryBuilder.来创建。MyBatis-Spring中，使用了SqlSessionFactoryBean来替代。SqlSessionFactoryBean有一个必须属性dataSource，另外其还有一个通用属性configLocation（用来指定mybatis的xml配置文件路径）。

SqlSessionFactoryBean即相当于原生mybatis中的SqlSessionFactoryBuilder












//使用方法：
@RepositorypublicclassUserDao{@ResourceprivateSqlSessionTemplatesqlSessionTemplate;publicUsergetUser(intid){returnsqlSessionTemplate.selectOne(this.getClass().getName()+".getUser",1);}}

为什么可以这样写，来看一下SqlSessionTemplate

publicclassSqlSessionTemplateimplementsSqlSession{privatefinalSqlSessionFactorysqlSessionFactory;privatefinalExecutorTypeexecutorType;privatefinalSqlSessionsqlSessionProxy;privatefinalPersistenceExceptionTranslatorexceptionTranslator;/***ConstructsaSpringmanagedSqlSessionwiththe{@codeSqlSessionFactory}*providedasanargument.**@paramsqlSessionFactory*/publicSqlSessionTemplate(SqlSessionFactorysqlSessionFactory){this(sqlSessionFactory,sqlSessionFactory.getConfiguration().getDefaultExecutorType());}
........省略......
publicSqlSessionTemplate(SqlSessionFactorysqlSessionFactory,ExecutorTypeexecutorType,PersistenceExceptionTranslatorexceptionTranslator){notNull(sqlSessionFactory,"Property'sqlSessionFactory'isrequired");notNull(executorType,"Property'executorType'isrequired");this.sqlSessionFactory=sqlSessionFactory;this.executorType=executorType;this.exceptionTranslator=exceptionTranslator;this.sqlSessionProxy=(SqlSession)newProxyInstance(SqlSessionFactory.class.getClassLoader(),newClass[]{SqlSession.class},newSqlSessionInterceptor());}
}

如上面代码所示，SqlSessionTemplate类实现了原生Mybatis中的SqlSession接口，实际上它就是原生mybatis中的SqlSession

方法三：采用抽象类org.mybatis.spring.support.SqlSessionDaoSupport提供SqlSession








publicclassBaseDaoextendsSqlSessionDaoSupport{//使用sqlSessionFactory@AutowiredprivateSqlSessionFactorysqlSessionFactory;
@AutowiredpublicvoidsetSqlSessionFactory(SqlSessionFactorysqlSessionFactory)
{
super.setSqlSessionFactory(sqlSessionFactory);
}/***执行insert操作*@paramstatement*@return*/publicintinsert(Stringstatement){
returngetSqlSession().insert(statement);}/***执行insert操作*@paramstatement*@paramparameter*@return*/publicintinsert(Stringstatement,Objectparameter){
returngetSqlSession().insert(statement,parameter);}
publicintupdate(Stringstatement)
{returngetSqlSession().update(statement);
}
publicintupdate(Stringstatement,Objectparameter){returngetSqlSession().update(statement,parameter);}
publicintdelete(Stringstatement)
{
returngetSqlSession().delete(statement);
}
publicintdelete(Stringstatement,Objectparameter){
returngetSqlSession().delete(statement,parameter);}/***获取一个list集合*@paramstatement*@return*/publicListselectList(Stringstatement){returngetSqlSession().selectList(statement);}/***根据参数获取一个list集合*@paramstatement*@paramparameter*@return*/publicListselectList(Stringstatement,Objectparameter){returngetSqlSession().selectList(statement,parameter);}publicMapselectMap(Stringstatement,StringmapKey){returngetSqlSession().selectMap(statement,mapKey);}publicMapselectMap(Stringstatement,Objectparameter,StringmapKey){returngetSqlSession().selectMap(statement,parameter,mapKey);}/***获取Object对象*@paramstatement*@return*/publicObjectselectOne(Stringstatement){returngetSqlSession().selectOne(statement);}/***获取connection,以便执行较为复杂的用法*@return*/publicConnectiongetConnection(){returngetSqlSession().getConnection();}}

如上代码，一个Dao类继承了SqlSessionDaoSupport类后，就可以在类中注入SessionFact
ory，进而通过getSqlSession()获取当前SqlSession

下面是SqlSessionDaoSupport的源码，它是一个抽象类，并拥有sqlSession属性，在setSqlSessionFactory方法中实例化了该sqlSession：

publicabstractclassSqlSessionDaoSupportextendsDaoSupport
{
privateSqlSessionsqlSession;privatebooleanexternalSqlSession;
publicvoidsetSqlSessionFactory(SqlSessionFactorysqlSessionFactory)
{
if(!this.externalSqlSession){
this.sqlSession=newSqlSessionTemplate(sqlSessionFactory);
}
}
publicvoidsetSqlSessionTemplate(SqlSessionTemplatesqlSessionTemplate)
{
this.sqlSession=sqlSessionTemplate;this.externalSqlSession=true;
}
publicSqlSessiongetSqlSession()
{
returnthis.sqlSession;
}
protectedvoidcheckDaoConfig()
{
notNull(this.sqlSession,"Property'sqlSessionFactory'or'sqlSessionTemplate'arerequired");}}

方法四：（也是最常见的使用方法，使用MapperScannerConfigurer，它将会查找类路径下的映射器并自动将它们创建成MapperFactoryBean）

由于直接使用MapperFactoryBean会在配置文件中配置大量mapper，因此这里使用包扫描的方式通过注解获取该bean












//使用如下代码，即可完成注入
@Resource
privateUserDaouserDao;

下面看一下MapperScannerConfigurer这个类：

publicclassMapperScannerConfigurerimplementsBeanDefinitionRegistryPostProcessor,InitializingBean,ApplicationContextAware,BeanNameAware{privateStringbasePackage;privatebooleanaddToConfig=true;privateSqlSessionFactorysqlSessionFactory;privateSqlSessionTemplatesqlSessionTemplate;privateStringsqlSessionFactoryBeanName;privateStringsqlSessionTemplateBeanName;privateClassannotationClass;privateClassmarkerInterface;privateApplicationContextapplicationContext;privateStringbeanName;privatebooleanprocessPropertyPlaceHolders;privateBeanNameGeneratornameGenerator;
publicvoidpostProcessBeanDefinitionRegistry(BeanDefinitionRegistryregistry)throwsBeansException{if(this.processPropertyPlaceHolders){processPropertyPlaceHolders();}ClassPathMapperScannerscanner=newClassPathMapperScanner(registry);scanner.setAddToConfig(this.addToConfig);scanner.setAnnotationClass(this.annotationClass);scanner.setMarkerInterface(this.markerInterface);scanner.setSqlSessionFactory(this.sqlSessionFactory);scanner.setSqlSessionTemplate(this.sqlSessionTemplate);scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName);scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName);scanner.setResourceLoader(this.applicationContext);scanner.setBeanNameGenerator(this.nameGenerator);scanner.registerFilters();scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage,ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));}
ClassPathMapperScanner：
publicSetdoScan(String...basePackages){SetbeanDefinitions=super.doScan(basePackages);if(beanDefinitions.isEmpty()){logger.warn("NoMyBatismapperwasfoundin'"+Arrays.toString(basePackages)+"'package.Pleasecheckyourconfiguration.");}else{for(BeanDefinitionHolderholder:beanDefinitions){GenericBeanDefinitiondefinition=(GenericBeanDefinition)holder.getBeanDefinition();if(logger.isDebugEnabled()){logger.debug("CreatingMapperFactoryBeanwithname'"+holder.getBeanName()+"'and'"+definition.getBeanClassName()+"'mapperInterface");}//themapperinterfaceistheoriginalclassofthebean//but,theactualclassofthebeanisMapperFactoryBeandefinition.getPropertyValues().add("mapperInterface",definition.getBeanClassName());definition.setBeanClass(MapperFactoryBean.class);definition.getPropertyValues().add("addToConfig",this.addToConfig);booleanexplicitFactoryUsed=false;if(StringUtils.hasText(this.sqlSessionFactoryBeanName)){definition.getPropertyValues().add("sqlSessionFactory",newRuntimeBeanReference(this.sqlSessionFactoryBeanName));explicitFactoryUsed=true;}elseif(this.sqlSessionFactory!=null){definition.getPropertyValues().add("sqlSessionFactory",this.sqlSessionFactory);explicitFactoryUsed=true;}if(StringUtils.hasText(this.sqlSessionTemplateBeanName)){if(explicitFactoryUsed){logger.warn("Cannotuseboth:sqlSessionTemplateandsqlSessionFactorytogether.sqlSessionFactoryisignored.");}definition.getPropertyValues().add("sqlSessionTemplate",newRuntimeBeanReference(this.sqlSessionTemplateBeanName));explicitFactoryUsed=true;}elseif(this.sqlSessionTemplate!=null){if(explicitFactoryUsed){logger.warn("Cannotuseboth:sqlSessionTemplateandsqlSessionFactorytogether.sqlSessionFactoryisignored.");}definition.getPropertyValues().add("sqlSessionTemplate",this.sqlSessionTemplate);explicitFactoryUsed=true;}if(!explicitFactoryUsed){if(logger.isDebugEnabled()){logger.debug("EnablingautowirebytypeforMapperFactoryBeanwithname'"+holder.getBeanName()+"'.");}definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);}}}returnbeanDefinitions;}

总结：spring-mybatis与原生Mybatis相比，如下概念：

1）SqlSessionFactory类在两者中都存在

2）前者用SqlSessionFactoryBean生成SqlSessionFactory，后者则使用SqlSessionFactoryBuilder;

3）前者使用SqlSessionTemplate，后者使用SqlSession，实际上前者实现了后者

4）MapperFactoryBean中实现了原生mybatis中下面的步骤，因此通过该类可以直接获取到一个mapper接口的实现对象

EmployeeMappermapper=session.getMapper(EmployeeMapper.class);

总结

以上所述是小编给大家介绍的spring-mybatis与原生mybatis使用对比分析，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对毛票票网站的支持！

spring-mybatis与原生mybatis使用对比分析

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