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1.配置 在spring配置文件中添加如下配置： <!-- SqlSessionFactory bean配置。configuration与configLocation可以选择其中一个配置， 若都配置了则使用configuration配置，若都不配置使用默认配置--> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"/> <!--配置方式：setter注入--> <property name="configuration" ref="configuration"/> <!--配置方式：配置文件--> <property name="configLocation" value="classpath:config/mybatis-config.xml"/> <property name="mapperLocations" value="classpath:com/wxyh/study/dao/**/*.xml"/> <!--注入其他属性--> </bean> <!-- spring与mybatis整合配置，扫描所有dao --> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.wxyh.study.dao.**.mapper"/> <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/> </bean>
2.SqlSessionFactoryBean源码解析 public class SqlSessionFactoryBean implements FactoryBean ApplicationListener // 核心字段，这些属性都提供了setter注入方法 private Resource configLocation; private Configuration configuration; private Resource[] mapperLocations; private DataSource dataSource; private TransactionFactory transactionFactory; private SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder(); private SqlSessionFactory sqlSessionFactory; private String environment = SqlSessionFactoryBean.class.getSimpleName(); private boolean failFast; private Interceptor[] plugins; private TypeHandler[] typeHandlers; private String typeHandlersPackage; private Class[] typeAliases; private String typeAliasesPackage; private Class typeAliasesSuperType; private DatabaseIdProvider databaseIdProvider; private Class vfs; private Cache cache; private ObjectFactory objectFactory; private ObjectWrapperFactory objectWrapperFactory; @Override 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(); }
protected SqlSessionFactory buildSqlSessionFactory() throws IOException {
Configuration configuration; XMLConfigBuilder xmlConfigBuilder = null; if (this.configuration != null) { // 注入了configuration bean，优先使用 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) { // 有配置文件，后面会解析配置文件，把相关配置保存在configuration中 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"); } // 没有配置configuration与configLocation，使用默认配置 configuration = new Configuration(); if (this.configurationProperties != null) { configuration.setVariables(this.configurationProperties); } }
// 略去设置或解析setter注入属性代码，有 // objectFactory,objectWrapperFactory,vfs,typeAliasesPackage,typeAliases, // plugins,typeHandlersPackage,typeHandlers,databaseIdProvider,cache ......
if (xmlConfigBuilder != null) { try { // 解析配置文件mybatis-config.xml， // 详细源码解析见： 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(); } } if (this.transactionFactory == null) { this.transactionFactory = new SpringManagedTransactionFactory(); } configuration.setEnvironment(new Environment(this.environment, this.transactionFactory, this.dataSource)); // 解析mapperLocations指定mapper配置文件 if (!isEmpty(this.mapperLocations)) { for (Resource mapperLocation : this.mapperLocations) { if (mapperLocation == null) { continue; } try { // 逐个解析mapper配置文件， // 解析源码见： 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 + "'"); } } } else { if (LOGGER.isDebugEnabled()) { LOGGER.debug("Property 'mapperLocations' was not specified or no matching resources found"); } }
// 构建sqlSessionFactory对象 return this.sqlSessionFactoryBuilder.build(configuration); }
@Override public SqlSessionFactory getObject() throws Exception { if (this.sqlSessionFactory == null) { afterPropertiesSet(); }
return this.sqlSessionFactory; }
}
SqlSessionFactoryBean是SqlSessionFactory的工厂bean。 启动项目时spring首先会创建SqlSessionFactoryBean对象，然后会把getObject()的返回值DefaultSqlSessionFactory对象作为bean注册到容器中。
3.MapperScannerConfigurer源码解析
public class MapperScannerConfigurer implements BeanDefinitionRegistryPostProcessor, InitializingBean, ApplicationContextAware, BeanNameAware {
// 核心字段，这些属性都提供了setter注入方法 private String basePackage; private boolean addToConfig = true; private SqlSessionFactory sqlSessionFactory; private SqlSessionTemplate sqlSessionTemplate; private String sqlSessionFactoryBeanName; private String sqlSessionTemplateBeanName; // mapper接口使用的注解类型 private Class annotationClass; // mapper接口的父接口类型 private Class markerInterface; private ApplicationContext applicationContext; private String beanName; private boolean processPropertyPlaceHolders; private BeanNameGenerator nameGenerator;
@Override public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) { if (this.processPropertyPlaceHolders) { processPropertyPlaceHolders(); }
ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry); scanner.setAddToConfig(this.addToConfig); // 设置mapper接口使用的注解或父类型 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); // 配置过滤basePackage包中mapper接口的规则，源码分析见4 scanner.registerFilters(); // 扫描basePackage包中mapper接口，将其封装为MapperFactoryBean scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS)); }
......
}
4.ClassPathMapperScanner源码解析
public class ClassPathMapperScanner extends ClassPathBeanDefinitionScanner { // 核心字段，这些属性都提供了setter注入方法 private boolean addToConfig = true; private SqlSessionFactory sqlSessionFactory; private SqlSessionTemplate sqlSessionTemplate; private String sqlSessionTemplateBeanName; private String sqlSessionFactoryBeanName; private Class annotationClass; private Class markerInterface; private MapperFactoryBean mapperFactoryBean = new MapperFactoryBean
/** * 配置扫描器以注册basePackage包中正确的接口为mapper */ public void registerFilters() { boolean acceptAllInterfaces = true;
// 把basePackage包中有annotationClass类型注解的所有接口注册为mapper if (this.annotationClass != null) { addIncludeFilter(new AnnotationTypeFilter(this.annotationClass)); acceptAllInterfaces = false; }
// 把basePackage包中派生自markerInterface类型接口的所有接口注册为mapper， // 重写matchClassName方法，以免注册markerInterface接口为mapper if (this.markerInterface != null) { addIncludeFilter(new AssignableTypeFilter(this.markerInterface) { @Override protected boolean matchClassName(String className) { return false; } }); acceptAllInterfaces = false; }
if (acceptAllInterfaces) { // 如果没有设置annotationClass和markerInterface，则注册basePackage包中所有类为mapper // default include filter that accepts all classes addIncludeFilter(new TypeFilter() { @Override public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException { return true; } }); }
// exclude package-info.java addExcludeFilter(new TypeFilter() { @Override public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException { String className = metadataReader.getClassMetadata().getClassName(); return className.endsWith("package-info"); } }); }
/** * Calls the parent search that will search and register all the candidates. * Then the registered objects are post processed to set them as * MapperFactoryBeans */ @Override public Set // 调用父类方法，扫描basePackages包中的mapper接口，返回BeanDefinitionHolder集合 Set
if (beanDefinitions.isEmpty()) { logger.warn("No MyBatis mapper was found in '" + Arrays.toString(basePackages) + "' package. Please check your configuration."); } else { processBeanDefinitions(beanDefinitions); }
return beanDefinitions; }
/** * 定义mapper的工厂bean MapperFactoryBean */ private void processBeanDefinitions(Set GenericBeanDefinition definition; for (BeanDefinitionHolder holder : beanDefinitions) { 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 // 通过构造函数传参设置MapperFactoryBean所生产bean的类型 definition.getConstructorArgumentValues().addGenericArgumentValue(definition.getBeanClassName()); // issue #59 definition.setBeanClass(this.mapperFactoryBean.getClass());
definition.getPropertyValues().add("addToConfig", this.addToConfig);
// 往MapperFactoryBean注入sqlSessionFactory 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; }
// 往MapperFactoryBean注入sqlSessionTemplate. // 如果已注入sqlSessionFactory则忽略该配置，使用sqlSessionTemplate，详见源码 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); } } }
}
5.MapperFactoryBean源码解析
public class MapperFactoryBean
// mapper bean的类型 private Class // true，添加mapper到MapperRegistry private boolean addToConfig = true;
public MapperFactoryBean() { //intentionally empty } public MapperFactoryBean(Class this.mapperInterface = mapperInterface; }
@Override protected void checkDaoConfig() { super.checkDaoConfig();
notNull(this.mapperInterface, "Property 'mapperInterface' is required");
Configuration configuration = getSqlSession().getConfiguration(); if (this.addToConfig && !configuration.hasMapper(this.mapperInterface)) { try { // 添加mapper到MapperRegistry，源码分析见xxxxxxxxxxx configuration.addMapper(this.mapperInterface); } catch (Exception e) { logger.error("Error while adding the mapper '" + this.mapperInterface + "' to configuration.", e); throw new IllegalArgumentException(e); } finally { ErrorContext.instance().reset(); } } }
@Override public T getObject() throws Exception { // getSqlSession()返回的是一个SqlSessionTemplate对象 // getMapper方法从MapperRegistry中获取的是MapperProxyFactory对象 return getSqlSession().getMapper(this.mapperInterface); }
}
public abstract class SqlSessionDaoSupport extends DaoSupport {
// 通过sqlSessionFactory或sqlSessionTemplate，生成的sqlSession对象都是SqlSessionTemplate类型， // 实际上是SqlSession的代理对象 private SqlSession sqlSession; private boolean externalSqlSession;
public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) { if (!this.externalSqlSession) { // 如果设置了sqlSessionTemplate，则不再使用sqlSessionFactory了 this.sqlSession = new SqlSessionTemplate(sqlSessionFactory); } }
public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) { this.sqlSession = sqlSessionTemplate; this.externalSqlSession = true; }
/** * Users should use this method to get a SqlSession to call its statement methods * This is SqlSession is managed by spring. Users should not commit/rollback/close it * because it will be automatically done. * * @return Spring managed thread safe SqlSession */ public SqlSession getSqlSession() { return this.sqlSession; }
@Override protected void checkDaoConfig() { notNull(this.sqlSession, "Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required"); }
}
6.SqlSessionTemplate源码解析
public class SqlSessionTemplate implements SqlSession, DisposableBean {
private final SqlSessionFactory sqlSessionFactory; private final ExecutorType executorType; // SqlSession的代理对象 private final SqlSession sqlSessionProxy; private final PersistenceExceptionTranslator exceptionTranslator;
public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory) { this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType()); }
public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType) { this(sqlSessionFactory, executorType, new MyBatisExceptionTranslator( sqlSessionFactory.getConfiguration().getEnvironment().getDataSource(), true)); }
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; // 创建sqlSession的代理对象，调用sqlSession的所有方法，都被SqlSessionInterceptor的invoke方法拦截 this.sqlSessionProxy = (SqlSession) newProxyInstance( SqlSessionFactory.class.getClassLoader(), new Class[] { SqlSession.class }, new SqlSessionInterceptor()); }
/** * 内部类 * jdk动态代理拦截器类 */ private class SqlSessionInterceptor implements InvocationHandler { @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { SqlSession sqlSession = getSqlSession( SqlSessionTemplate.this.sqlSessionFactory, SqlSessionTemplate.this.executorType, SqlSessionTemplate.this.exceptionTranslator); try { Object result = method.invoke(sqlSession, args); if (!isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) { // force commit even on non-dirty sessions because some databases require // a commit/rollback before calling close() sqlSession.commit(true); } return result; } catch (Throwable t) { Throwable unwrapped = unwrapThrowable(t); if (SqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) { // release the connection to avoid a deadlock if the translator is no loaded. See issue #22 closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory); sqlSession = null; Throwable translated = SqlSessionTemplate.this.exceptionTranslator.translateExceptionIfPossible((PersistenceException) unwrapped); if (translated != null) { unwrapped = translated; } } throw unwrapped; } finally { if (sqlSession != null) { closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory); } } } }
}
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