原生mybatis使用方法：
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String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); try { Employee employee = new Employee(null, "doubi", "1", "ddd@sys.com"); EmployeeMapper mapper = session.getMapper(EmployeeMapper.class); mapper.addEmp(employee); session.commit(); } finally { session.close(); } |
spring使用方法，直接注入即可
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@AutowiredEmployeeMapper employeeMapper |
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）
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<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"/> <property name="configLocation" value="classpath:mybatis-config.xml"></property> <!-- 自动扫描mapping.xml文件 --> <property name="mapperLocations" value="classpath:mapper/*.xml"></property> </bean><!--上面生成sqlSessionFactory的几个方法基本相同--><bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean"> <property name="mapperInterface" value="org.mybatis.spring.sample.mapper.UserMapper" /> <property name="sqlSessionFactory" ref="sqlSessionFactory" /></bean> |
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
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<!-- spring和MyBatis完美整合，不需要mybatis的配置映射文件 --> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="configLocation" value="classpath:sqlMapConfig.xml"/> <!-- 自动扫描mapping.xml文件，**表示迭代查找,也可在sqlMapConfig.xml中单独指定xml文件--> <property name="mapperLocations" value="classpath:com/hua/saf/**/*.xml" /> </bean> <!-- mybatis spring sqlSessionTemplate,使用时直接让spring注入即可 --> <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate"> <constructor-arg index="0" ref="sqlSessionFactory"></constructor-arg> </bean>//使用方法：@Repositorypublic class UserDao{ @Resource private SqlSessionTemplate sqlSessionTemplate; public User getUser(int id) { return sqlSessionTemplate.selectOne(this.getClass().getName() + ".getUser", 1); } } |
为什么可以这样写，来看一下SqlSessionTemplate
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public class SqlSessionTemplate implements SqlSession { private final SqlSessionFactory sqlSessionFactory; private final ExecutorType executorType; private final SqlSession sqlSessionProxy; private final PersistenceExceptionTranslator exceptionTranslator; /** * Constructs a Spring managed SqlSession with the {@code SqlSessionFactory} * provided as an argument. * * @param sqlSessionFactory */ public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory) { this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType()); }........省略...... public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType, PersistenceExceptionTranslator exceptionTranslator) { notNull(sqlSessionFactory, "Property 'sqlSessionFactory' is required"); notNull(executorType, "Property 'executorType' is required"); this.sqlSessionFactory = sqlSessionFactory; this.executorType = executorType; this.exceptionTranslator = exceptionTranslator; this.sqlSessionProxy = (SqlSession) newProxyInstance( SqlSessionFactory.class.getClassLoader(), new Class[] { SqlSession.class }, new SqlSessionInterceptor()); }} |
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
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<!-- spring和MyBatis完美整合，不需要mybatis的配置映射文件 --> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="configLocation" value="classpath:sqlMapConfig.xml"/> <!-- 自动扫描mapping.xml文件，**表示迭代查找,也可在sqlMapConfig.xml中单独指定xml文件--> <property name="mapperLocations" value="classpath:com/hua/saf/**/*.xml" /> </bean>public class BaseDao extends SqlSessionDaoSupport{ //使用sqlSessionFactory @Autowired private SqlSessionFactory sqlSessionFactory; @Autowired public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) { super.setSqlSessionFactory(sqlSessionFactory); } /** * 执行insert操作 * @param statement * @return */ public int insert(String statement) { return getSqlSession().insert(statement); } /** * 执行insert操作 * @param statement * @param parameter * @return */ public int insert(String statement, Object parameter) { return getSqlSession().insert(statement, parameter); } public int update(String statement){ return getSqlSession().update(statement);}public int update(String statement, Object parameter) { return getSqlSession().update(statement, parameter); } public int delete(String statement){ return getSqlSession().delete(statement); } public int delete(String statement, Object parameter) { return getSqlSession().delete(statement, parameter); } /** * 获取一个list集合 * @param statement * @return */ public List<?> selectList(String statement) { return getSqlSession().selectList(statement); } /** * 根据参数 获取一个list集合 * @param statement * @param parameter * @return */ public List<?> selectList(String statement, Object parameter) { return getSqlSession().selectList(statement, parameter); } public Map<?, ?> selectMap(String statement, String mapKey) { return getSqlSession().selectMap(statement, mapKey); } public Map<?, ?> selectMap(String statement, Object parameter, String mapKey) { return getSqlSession().selectMap(statement, parameter, mapKey); } /** * 获取Object对象 * @param statement * @return */ public Object selectOne(String statement) { return getSqlSession().selectOne(statement); } /** * 获取connection, 以便执行较为复杂的用法 * @return */ public Connection getConnection() { return getSqlSession().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：
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public abstract class SqlSessionDaoSupport extends DaoSupport{ private SqlSession sqlSession; private boolean externalSqlSession; public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory){ if (!this.externalSqlSession) { this.sqlSession = new SqlSessionTemplate(sqlSessionFactory); } } public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate){ this.sqlSession = sqlSessionTemplate; this.externalSqlSession = true; } public SqlSession getSqlSession() { return this.sqlSession; } protected void checkDaoConfig() { notNull(this.sqlSession, "Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required"); }} |
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
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<!-- spring和MyBatis完美整合，不需要mybatis的配置映射文件 --> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <!-- 自动扫描mapping.xml文件，**表示迭代查找 --> <property name="mapperLocations" value="classpath:com/hua/saf/**/*.xml" /> </bean> <!-- DAO接口所在包名，Spring会自动查找其下的类 ,包下的类需要使用@MapperScan注解,否则容器注入会失败 --> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.hua.saf.*" /> <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" /> </bean>//使用如下代码，即可完成注入@Resourceprivate UserDao userDao; |
下面看一下MapperScannerConfigurer这个类：
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public class MapperScannerConfigurer implements BeanDefinitionRegistryPostProcessor, InitializingBean, ApplicationContextAware, BeanNameAware { private String basePackage; private boolean addToConfig = true; private SqlSessionFactory sqlSessionFactory; private SqlSessionTemplate sqlSessionTemplate; private String sqlSessionFactoryBeanName; private String sqlSessionTemplateBeanName; private Class<? extends Annotation> annotationClass; private Class<?> markerInterface; private ApplicationContext applicationContext; private String beanName; private boolean processPropertyPlaceHolders; private BeanNameGenerator nameGenerator;public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException { if (this.processPropertyPlaceHolders) { processPropertyPlaceHolders(); } ClassPathMapperScanner scanner = new ClassPathMapperScanner(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 ：public Set<BeanDefinitionHolder> doScan(String... basePackages) { Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages); if (beanDefinitions.isEmpty()) { logger.warn("No MyBatis mapper was found in '" + Arrays.toString(basePackages) + "' package. Please check your configuration."); } else { for (BeanDefinitionHolder holder : beanDefinitions) { GenericBeanDefinition definition = (GenericBeanDefinition) holder.getBeanDefinition(); if (logger.isDebugEnabled()) { logger.debug("Creating MapperFactoryBean with name '" + holder.getBeanName() + "' and '" + definition.getBeanClassName() + "' mapperInterface"); } // the mapper interface is the original class of the bean // but, the actual class of the bean is MapperFactoryBean definition.getPropertyValues().add("mapperInterface", definition.getBeanClassName()); definition.setBeanClass(MapperFactoryBean.class); definition.getPropertyValues().add("addToConfig", this.addToConfig); boolean explicitFactoryUsed = false; if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) { definition.getPropertyValues().add("sqlSessionFactory", new RuntimeBeanReference(this.sqlSessionFactoryBeanName)); explicitFactoryUsed = true; } else if (this.sqlSessionFactory != null) { definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory); explicitFactoryUsed = true; } if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) { if (explicitFactoryUsed) { logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored."); } definition.getPropertyValues().add("sqlSessionTemplate", new RuntimeBeanReference(this.sqlSessionTemplateBeanName)); explicitFactoryUsed = true; } else if (this.sqlSessionTemplate != null) { if (explicitFactoryUsed) { logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored."); } definition.getPropertyValues().add("sqlSessionTemplate", this.sqlSessionTemplate); explicitFactoryUsed = true; } if (!explicitFactoryUsed) { if (logger.isDebugEnabled()) { logger.debug("Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'."); } definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE); } } } return beanDefinitions; } |
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
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EmployeeMapper mapper = 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服务器之家网站的支持！
原文链接：https://www.tuicool.com/articles/AN7NfiE
