Spring-Mybatis源码分析
2017-07-11 17:50
295 查看
首先给出Spring-mybatis的配置文件
<!-- 配置数据源 -->
<bean id="dataSource" class="com.jolbox.bonecp.BoneCPDataSource"
destroy-method="close">
<property name="driverClass" value="${DriverClasses}" />
<property name="jdbcUrl" value="${ecology.url}" />
<property name="username" value="${ecology.user}" />
<property name="password" value="${ecology.password}" />
<property name="idleConnectionTestPeriod" value="60" />
<property name="idleMaxAge" value="240" />
<property name="maxConnectionsPerPartition" value="30" />
<property name="minConnectionsPerPartition" value="10" />
<property name="partitionCount" value="1" />
<property name="acquireIncrement" value="5" />
<property name="statementsCacheSize" value="100" />
<property name="releaseHelperThreads" value="3" />
</bean>
<!-- 配置数据工厂 -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 自动扫描mapper.xml文件 -->
<property name="configLocation" value="classpath:cn/resources/mybatis-cfg.xml" />
<property name="mapperLocations" value="classpath:cn/resources/mapper/*Mapper.xml" />
<property name="dataSource" ref="dataSource" />
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
<property name="basePackage" value="cn.belle.mapper"></property>
</bean>
mybatis-cfg.xml
<configuration>
<settings>
<!-- 启用自动将数据库字段和pojo中的字段做驼峰式的匹配 -->
<setting name="mapUnderscoreToCamelCase" value="true"/>
<!-- 懒加载模式 -->
<setting name="lazyLoadingEnabled" value="false" />
<!-- JdbcType enumeration. Most common are: NULL, VARCHAR and OTHER -->
<setting name="jdbcTypeForNull" value="NULL" />
<setting name="defaultStatementTimeout" value="30" />
</settings>
</configuration>
核心类是MapperScannerConfigurer
public class MapperScannerConfigurer implements BeanDefinitionRegistryPostProcessor, InitializingBean, ApplicationContextAware, BeanNameAware这个类实现了BeanDefinitionRegistryPostProcessor这个抽象接口，让Spring容器在加载时执行postProcessBeanDefinitionRegistry方法
1 public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
2 if (this.processPropertyPlaceHolders) {
3 processPropertyPlaceHolders();
4 }
5
6 ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
7 scanner.setAddToConfig(this.addToConfig);
8 scanner.setAnnotationClass(this.annotationClass);
9 scanner.setMarkerInterface(this.markerInterface);
10 scanner.setSqlSessionFactory(this.sqlSessionFactory);
11 scanner.setSqlSessionTemplate(this.sqlSessionTemplate);
12 scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName);
13 scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName);
14 scanner.setResourceLoader(this.applicationContext);
15 scanner.setBeanNameGenerator(this.nameGenerator);
16 scanner.registerFilters();
17 scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));
18 }可以看到 scanner设置了大量属性，并且最后执行了scan方法
public int scan(String[] basePackages)
/* */ {
/* 224 */ int beanCountAtScanStart = this.registry.getBeanDefinitionCount();
/* */
/* 226 */ doScan(basePackages);
/* */
/* */
/* 229 */ if (this.includeAnnotationConfig) {
/* 230 */ AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
/* */ }
/* */
/* 233 */ return this.registry.getBeanDefinitionCount() - beanCountAtScanStart;
/* */ }
doScan（注意这里不要搞错了，之前我就搞错了，这里的scan应该是子类的sacn）
public Set<BeanDefinitionHolder> doScan(String[] basePackages)
/* */ {
/* 164 */ Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
/* */
/* 166 */ if (beanDefinitions.isEmpty()) {
/* 167 */ this.logger.warn("No MyBatis mapper was found in '" + Arrays.toString(basePackages) + "' package. Please check your configuration.");
/* */ } else {
/* 169 */ processBeanDefinitions(beanDefinitions);
/* */ }
/* */
/* 172 */ return beanDefinitions;
/* */ }
首先调用了父类的doScan
Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);父类的doScan
该方法主要做了以下操作：
1）扫描basePackage下面的java文件
2）解析扫描到的java文件
3）调用各个在上一步骤注册的过滤器，执行相应的方法。
4）为解析后的java注册bean，注册方式采用编码的动态注册实现。
5）构造MapperFactoryBean的属性，mapperInterface，sqlSessionFactory等等，填充到BeanDefinition里面去。
做完这些，MapperFactoryBean对象也就构造完成了，扫描方式添加dao的工作也完成了。
然后是processBeanDefinitions private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions)
/* */ {
/* 177 */ for (BeanDefinitionHolder holder : beanDefinitions) {
/* 178 */ GenericBeanDefinition definition = (GenericBeanDefinition)holder.getBeanDefinition();
/* */
/* 180 */ if (this.logger.isDebugEnabled()) {
/* 181 */ this.logger.debug("Creating MapperFactoryBean with name '" + holder.getBeanName() + "' and '" + definition
/* 182 */ .getBeanClassName() + "' mapperInterface");
/* */ }
/* */
/* */
/* */
/* 187 */ definition.getConstructorArgumentValues().addGenericArgumentValue(definition.getBeanClassName());
/* 188 */ definition.setBeanClass(this.mapperFactoryBean.getClass());
/* */
/* 190 */ definition.getPropertyValues().add("addToConfig", Boolean.valueOf(this.addToConfig));
/* */
/* 192 */ boolean explicitFactoryUsed = false;
/* 193 */ if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) {
/* 194 */ definition.getPropertyValues().add("sqlSessionFactory", new RuntimeBeanReference(this.sqlSessionFactoryBeanName));
/* 195 */ explicitFactoryUsed = true;
/* 196 */ } else if (this.sqlSessionFactory != null) {
/* 197 */ definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory);
/* 198 */ explicitFactoryUsed = true;
/* */ }
/* */
/* 201 */ if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) {
/* 202 */ if (explicitFactoryUsed) {
/* 203 */ this.logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
/* */ }
/* 205 */ definition.getPropertyValues().add("sqlSessionTemplate", new RuntimeBeanReference(this.sqlSessionTemplateBeanName));
/* 206 */ explicitFactoryUsed = true;
/* 207 */ } else if (this.sqlSessionTemplate != null) {
/* 208 */ if (explicitFactoryUsed) {
/* 209 */ this.logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
/* */ }
/* 211 */ definition.getPropertyValues(
ca0b
).add("sqlSessionTemplate", this.sqlSessionTemplate);
/* 212 */ explicitFactoryUsed = true;
/* */ }
/* */
/* 215 */ if (!explicitFactoryUsed) {
/* 216 */ if (this.logger.isDebugEnabled()) {
/* 217 */ this.logger.debug("Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'.");
/* */ }
/* 219 */ definition.setAutowireMode(2);
/* */ }
/* */ }
/* */ }最关键的两行
definition.getConstructorArgumentValues().addGenericArgumentValue(definition.getBeanClassName());
definition.setBeanClass(this.mapperFactoryBean.getClass());
到这里动态注册的过程已经实现，dao层的接口已经全部被改造成MapperFactoryBean
所以最终我们还是要分析MapperFactoryBean的实现原理！
MapperFactoryBean继承了SqlSessionDaoSupport类，SqlSessionDaoSupport类继承DaoSupport抽象类，DaoSupport抽象类实现了InitializingBean接口，因此实例个MapperFactoryBean的时候，都会调用InitializingBean接口的afterPropertiesSet方法。
MapperFactoryBean重写了checkDaoConfig方法
protected void checkDaoConfig()
/* */ {
/* 74 */ super.checkDaoConfig();
/* */
/* 76 */ Assert.notNull(this.mapperInterface, "Property 'mapperInterface' is required");
/* */
/* 78 */ Configuration configuration = getSqlSession().getConfiguration();
/* 79 */ if ((this.addToConfig) && (!configuration.hasMapper(this.mapperInterface))) {
/* */ try {
/* 81 */ configuration.addMapper(this.mapperInterface);
/* */ } catch (Exception e) {
/* 83 */ this.logger.error("Error while adding the mapper '" + this.mapperInterface + "' to configuration.", e);
/* 84 */ throw new IllegalArgumentException(e);
/* */ } finally {
/* 86 */ ErrorContext.instance().reset();
/* */ }
/* */ }
/* */ }
然后通过spring工厂拿对应的bean的时候：
public T getObject()
/* */ throws Exception
/* */ {
/* 96 */ return getSqlSession().getMapper(this.mapperInterface);
/* */ }
这里的SqlSession是SqlSessionTemplate，SqlSessionTemplate的getMapper方法：
public <T> T getMapper(Class<T> type)
/* */ {
/* 319 */ return getConfiguration().getMapper(type, this);
/* */ }
Configuration的getMapper方法，会使用MapperRegistry的getMapper方法：
public <T> T getMapper(Class<T> type, SqlSession sqlSession) {
/* 717 */ return this.mapperRegistry.getMapper(type, sqlSession);
/* */ }getMapper
*/ public <T> T getMapper(Class<T> type, SqlSession sqlSession)
/* */ {
/* 45 */ MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory)this.knownMappers.get(type);
/* 46 */ if (mapperProxyFactory == null) {
/* 47 */ throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
/* */ }
/* */ try {
/* 50 */ return mapperProxyFactory.newInstance(sqlSession);
/* */ } catch (Exception e) {
/* 52 */ throw new BindingException("Error getting mapper instance. Cause: " + e, e);
/* */ }
/* */ }
newInstance
protected T newInstance(MapperProxy<T> mapperProxy)
/* */ {
/* 47 */ return Proxy.newProxyInstance(this.mapperInterface.getClassLoader(), new Class[] { this.mapperInterface }, mapperProxy);
/* */ }
/* */
这里就出现了动态代理
mapperProxy的源码
public class MapperProxy<T>
/* */ implements InvocationHandler, Serializable
它的invoke
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
/* */ {
/* 45 */ if (Object.class.equals(method.getDeclaringClass())) {
/* */ try {
/* 47 */ return method.invoke(this, args);
/* */ } catch (Throwable t) {
/* 49 */ throw ExceptionUtil.unwrapThrowable(t);
/* */ }
/* */ }
/* 52 */ MapperMethod mapperMethod = cachedMapperMethod(method);
/* 53 */ return mapperMethod.execute(this.sqlSession, args);
/* */ }
这两行相信大家已经很熟悉了
MapperMethod mapperMethod = cachedMapperMethod(method);
/* 53 */ return mapperMethod.execute(this.sqlSession, args);
<!-- 配置数据源 -->
<bean id="dataSource" class="com.jolbox.bonecp.BoneCPDataSource"
destroy-method="close">
<property name="driverClass" value="${DriverClasses}" />
<property name="jdbcUrl" value="${ecology.url}" />
<property name="username" value="${ecology.user}" />
<property name="password" value="${ecology.password}" />
<property name="idleConnectionTestPeriod" value="60" />
<property name="idleMaxAge" value="240" />
<property name="maxConnectionsPerPartition" value="30" />
<property name="minConnectionsPerPartition" value="10" />
<property name="partitionCount" value="1" />
<property name="acquireIncrement" value="5" />
<property name="statementsCacheSize" value="100" />
<property name="releaseHelperThreads" value="3" />
</bean>
<!-- 配置数据工厂 -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 自动扫描mapper.xml文件 -->
<property name="configLocation" value="classpath:cn/resources/mybatis-cfg.xml" />
<property name="mapperLocations" value="classpath:cn/resources/mapper/*Mapper.xml" />
<property name="dataSource" ref="dataSource" />
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
<property name="basePackage" value="cn.belle.mapper"></property>
</bean>
mybatis-cfg.xml
<configuration>
<settings>
<!-- 启用自动将数据库字段和pojo中的字段做驼峰式的匹配 -->
<setting name="mapUnderscoreToCamelCase" value="true"/>
<!-- 懒加载模式 -->
<setting name="lazyLoadingEnabled" value="false" />
<!-- JdbcType enumeration. Most common are: NULL, VARCHAR and OTHER -->
<setting name="jdbcTypeForNull" value="NULL" />
<setting name="defaultStatementTimeout" value="30" />
</settings>
</configuration>
核心类是MapperScannerConfigurer
public class MapperScannerConfigurer implements BeanDefinitionRegistryPostProcessor, InitializingBean, ApplicationContextAware, BeanNameAware这个类实现了BeanDefinitionRegistryPostProcessor这个抽象接口，让Spring容器在加载时执行postProcessBeanDefinitionRegistry方法
1 public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
2 if (this.processPropertyPlaceHolders) {
3 processPropertyPlaceHolders();
4 }
5
6 ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
7 scanner.setAddToConfig(this.addToConfig);
8 scanner.setAnnotationClass(this.annotationClass);
9 scanner.setMarkerInterface(this.markerInterface);
10 scanner.setSqlSessionFactory(this.sqlSessionFactory);
11 scanner.setSqlSessionTemplate(this.sqlSessionTemplate);
12 scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName);
13 scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName);
14 scanner.setResourceLoader(this.applicationContext);
15 scanner.setBeanNameGenerator(this.nameGenerator);
16 scanner.registerFilters();
17 scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));
18 }可以看到 scanner设置了大量属性，并且最后执行了scan方法
public int scan(String[] basePackages)
/* */ {
/* 224 */ int beanCountAtScanStart = this.registry.getBeanDefinitionCount();
/* */
/* 226 */ doScan(basePackages);
/* */
/* */
/* 229 */ if (this.includeAnnotationConfig) {
/* 230 */ AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
/* */ }
/* */
/* 233 */ return this.registry.getBeanDefinitionCount() - beanCountAtScanStart;
/* */ }
doScan（注意这里不要搞错了，之前我就搞错了，这里的scan应该是子类的sacn）
public Set<BeanDefinitionHolder> doScan(String[] basePackages)
/* */ {
/* 164 */ Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
/* */
/* 166 */ if (beanDefinitions.isEmpty()) {
/* 167 */ this.logger.warn("No MyBatis mapper was found in '" + Arrays.toString(basePackages) + "' package. Please check your configuration.");
/* */ } else {
/* 169 */ processBeanDefinitions(beanDefinitions);
/* */ }
/* */
/* 172 */ return beanDefinitions;
/* */ }
首先调用了父类的doScan
Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);父类的doScan
protected Set<BeanDefinitionHolder> doScan(String... basePackages)
/* */ {
/* 245 */ Assert.notEmpty(basePackages, "At least one base package must be specified");
/* 246 */ Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet();
/* 247 */ for (String basePackage : basePackages) {
/* 248 */ Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
/* 249 */ for (BeanDefinition candidate : candidates) {
/* 250 */ ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
/* 251 */ candidate.setScope(scopeMetadata.getScopeName());
/* 252 */ String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
/* 253 */ if ((candidate instanceof AbstractBeanDefinition)) {
/* 254 */ postProcessBeanDefinition((AbstractBeanDefinition)candidate, beanName);
/* */ }
/* 256 */ if ((candidate instanceof AnnotatedBeanDefinition)) {
/* 257 */ AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition)candidate);
/* */ }
/* 259 */ if (checkCandidate(beanName, candidate)) {
/* 260 */ BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
/* 261 */ definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
/* 262 */ beanDefinitions.add(definitionHolder);
/* 263 */ registerBeanDefinition(definitionHolder, this.registry);
/* */ }
/* */ }
/* */ }
/* 267 */ return beanDefinitions;
/* */ }该方法主要做了以下操作：
1）扫描basePackage下面的java文件
2）解析扫描到的java文件
3）调用各个在上一步骤注册的过滤器，执行相应的方法。
4）为解析后的java注册bean，注册方式采用编码的动态注册实现。
5）构造MapperFactoryBean的属性，mapperInterface，sqlSessionFactory等等，填充到BeanDefinition里面去。
做完这些，MapperFactoryBean对象也就构造完成了，扫描方式添加dao的工作也完成了。
然后是processBeanDefinitions private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions)
/* */ {
/* 177 */ for (BeanDefinitionHolder holder : beanDefinitions) {
/* 178 */ GenericBeanDefinition definition = (GenericBeanDefinition)holder.getBeanDefinition();
/* */
/* 180 */ if (this.logger.isDebugEnabled()) {
/* 181 */ this.logger.debug("Creating MapperFactoryBean with name '" + holder.getBeanName() + "' and '" + definition
/* 182 */ .getBeanClassName() + "' mapperInterface");
/* */ }
/* */
/* */
/* */
/* 187 */ definition.getConstructorArgumentValues().addGenericArgumentValue(definition.getBeanClassName());
/* 188 */ definition.setBeanClass(this.mapperFactoryBean.getClass());
/* */
/* 190 */ definition.getPropertyValues().add("addToConfig", Boolean.valueOf(this.addToConfig));
/* */
/* 192 */ boolean explicitFactoryUsed = false;
/* 193 */ if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) {
/* 194 */ definition.getPropertyValues().add("sqlSessionFactory", new RuntimeBeanReference(this.sqlSessionFactoryBeanName));
/* 195 */ explicitFactoryUsed = true;
/* 196 */ } else if (this.sqlSessionFactory != null) {
/* 197 */ definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory);
/* 198 */ explicitFactoryUsed = true;
/* */ }
/* */
/* 201 */ if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) {
/* 202 */ if (explicitFactoryUsed) {
/* 203 */ this.logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
/* */ }
/* 205 */ definition.getPropertyValues().add("sqlSessionTemplate", new RuntimeBeanReference(this.sqlSessionTemplateBeanName));
/* 206 */ explicitFactoryUsed = true;
/* 207 */ } else if (this.sqlSessionTemplate != null) {
/* 208 */ if (explicitFactoryUsed) {
/* 209 */ this.logger.warn("Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
/* */ }
/* 211 */ definition.getPropertyValues(
ca0b
).add("sqlSessionTemplate", this.sqlSessionTemplate);
/* 212 */ explicitFactoryUsed = true;
/* */ }
/* */
/* 215 */ if (!explicitFactoryUsed) {
/* 216 */ if (this.logger.isDebugEnabled()) {
/* 217 */ this.logger.debug("Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'.");
/* */ }
/* 219 */ definition.setAutowireMode(2);
/* */ }
/* */ }
/* */ }最关键的两行
definition.getConstructorArgumentValues().addGenericArgumentValue(definition.getBeanClassName());
definition.setBeanClass(this.mapperFactoryBean.getClass());
到这里动态注册的过程已经实现，dao层的接口已经全部被改造成MapperFactoryBean
所以最终我们还是要分析MapperFactoryBean的实现原理！
MapperFactoryBean继承了SqlSessionDaoSupport类，SqlSessionDaoSupport类继承DaoSupport抽象类，DaoSupport抽象类实现了InitializingBean接口，因此实例个MapperFactoryBean的时候，都会调用InitializingBean接口的afterPropertiesSet方法。
public final void afterPropertiesSet() throws IllegalArgumentException, BeanInitializationException
/* */ {
/* 44 */ checkDaoConfig();
/* */
/* */ try
/* */ {
/* 48 */ initDao();
/* */ }
/* */ catch (Exception ex) {
/* 51 */ throw new BeanInitializationException("Initialization of DAO failed", ex);
/* */ }
/* */ }MapperFactoryBean重写了checkDaoConfig方法
protected void checkDaoConfig()
/* */ {
/* 74 */ super.checkDaoConfig();
/* */
/* 76 */ Assert.notNull(this.mapperInterface, "Property 'mapperInterface' is required");
/* */
/* 78 */ Configuration configuration = getSqlSession().getConfiguration();
/* 79 */ if ((this.addToConfig) && (!configuration.hasMapper(this.mapperInterface))) {
/* */ try {
/* 81 */ configuration.addMapper(this.mapperInterface);
/* */ } catch (Exception e) {
/* 83 */ this.logger.error("Error while adding the mapper '" + this.mapperInterface + "' to configuration.", e);
/* 84 */ throw new IllegalArgumentException(e);
/* */ } finally {
/* 86 */ ErrorContext.instance().reset();
/* */ }
/* */ }
/* */ }
然后通过spring工厂拿对应的bean的时候：
public T getObject()
/* */ throws Exception
/* */ {
/* 96 */ return getSqlSession().getMapper(this.mapperInterface);
/* */ }
这里的SqlSession是SqlSessionTemplate，SqlSessionTemplate的getMapper方法：
public <T> T getMapper(Class<T> type)
/* */ {
/* 319 */ return getConfiguration().getMapper(type, this);
/* */ }
Configuration的getMapper方法，会使用MapperRegistry的getMapper方法：
public <T> T getMapper(Class<T> type, SqlSession sqlSession) {
/* 717 */ return this.mapperRegistry.getMapper(type, sqlSession);
/* */ }getMapper
*/ public <T> T getMapper(Class<T> type, SqlSession sqlSession)
/* */ {
/* 45 */ MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory)this.knownMappers.get(type);
/* 46 */ if (mapperProxyFactory == null) {
/* 47 */ throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
/* */ }
/* */ try {
/* 50 */ return mapperProxyFactory.newInstance(sqlSession);
/* */ } catch (Exception e) {
/* 52 */ throw new BindingException("Error getting mapper instance. Cause: " + e, e);
/* */ }
/* */ }
newInstance
protected T newInstance(MapperProxy<T> mapperProxy)
/* */ {
/* 47 */ return Proxy.newProxyInstance(this.mapperInterface.getClassLoader(), new Class[] { this.mapperInterface }, mapperProxy);
/* */ }
/* */
这里就出现了动态代理
mapperProxy的源码
public class MapperProxy<T>
/* */ implements InvocationHandler, Serializable
它的invoke
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
/* */ {
/* 45 */ if (Object.class.equals(method.getDeclaringClass())) {
/* */ try {
/* 47 */ return method.invoke(this, args);
/* */ } catch (Throwable t) {
/* 49 */ throw ExceptionUtil.unwrapThrowable(t);
/* */ }
/* */ }
/* 52 */ MapperMethod mapperMethod = cachedMapperMethod(method);
/* 53 */ return mapperMethod.execute(this.sqlSession, args);
/* */ }
这两行相信大家已经很熟悉了
MapperMethod mapperMethod = cachedMapperMethod(method);
/* 53 */ return mapperMethod.execute(this.sqlSession, args);
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