一文带你理解透 MyBatis 源码

String resource = "mybatis-config.xml";//1.读取resources下面的mybatis-config.xml文件InputStream inputStream = Resources.getResourceAsStream(resource);//2.使用SqlSessionFactoryBuilder创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);//3.通过sqlSessionFactory创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();

public static InputStream getResourceAsStream(String resource) throws IOException {	return getResourceAsStream(null, resource);} //loader赋值为nullpublic static InputStream getResourceAsStream(ClassLoader loader, String resource) throws IOException {	InputStream in = classLoaderWrapper.getResourceAsStream(resource, loader);	if (in == null) {		throw new IOException("Could not find resource " + resource);	} 	return in;}//classLoader为nullpublic InputStream getResourceAsStream(String resource, ClassLoader classLoader) {	return getResourceAsStream(resource, getClassLoaders(classLoader));} //classLoader类加载InputStream getResourceAsStream(String resource, ClassLoader[] classLoader) {	for (ClassLoader cl : classLoader) {		if (null != cl) {			//加载指定路径文件流			InputStream returnValue = cl.getResourceAsStream(resource);			// now, some class loaders want this leading "/", so we'll add it and try again if we didn't find the resource			if (null == returnValue) {				returnValue = cl.getResourceAsStream("/" + resource);			} 			if (null != returnValue) {				return returnValue;			}		}	} 	return null;}

//SqlSessionFactoryBuilder是一个建造者模式SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);public SqlSessionFactory build(InputStream inputStream) {	return build(inputStream, null, null);}//XMLConfigBuilder也是建造者模式public SqlSessionFactory build(InputStream inputStream, String environment, Properties properties) {	try {		XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);		return build(parser.parse());	} catch (Exception e) {		throw ExceptionFactory.wrapException("Error building SqlSession.", e);	} finally {		ErrorContext.instance().reset();		try {			inputStream.close();		} catch (IOException e) {			// Intentionally ignore. Prefer previous error.		}	}}//接下来进入XMLConfigBuilder构造函数public XMLConfigBuilder(InputStream inputStream, String environment, Properties props) {	this(new XPathParser(inputStream, true, props, new XMLMapperEntityResolver()), environment, props);}//接下来进入this后,初始化Configurationprivate XMLConfigBuilder(XPathParser parser, String environment, Properties props) {	super(new Configuration());	ErrorContext.instance().resource("SQL Mapper Configuration");	this.configuration.setVariables(props);	this.parsed = false;	this.environment = environment;	this.parser = parser;}//其中parser.parse()负责解析xml,build(configuration)创建SqlSessionFactoryreturn build(parser.parse());

public Configuration parse() {	//判断是否重复解析	if (parsed) {		throw new BuilderException("Each XMLConfigBuilder can only be used once.");	} 	parsed = true;	//读取配置文件一级节点configuration	parseConfiguration(parser.evalNode("/configuration"));	return configuration;}

private void parseConfiguration(XNode root) {	try {		//properties 标签,用来配置参数信息，比如最常见的数据库连接信息		propertiesElement(root.evalNode("properties"));		Properties settings = settingsAsProperties(root.evalNode("settings"));		loadCustomVfs(settings);		loadCustomLogImpl(settings);		//实体别名两种方式:1.指定单个实体;2.指定包		typeAliasesElement(root.evalNode("typeAliases"));		//插件		pluginElement(root.evalNode("plugins"));		//用来创建对象(数据库数据映射成java对象时)		objectFactoryElement(root.evalNode("objectFactory"));		objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));		reflectorFactoryElement(root.evalNode("reflectorFactory"));		settingsElement(settings);		// read it after objectFactory and objectWrapperFactory issue #631		//数据库环境		environmentsElement(root.evalNode("environments"));		databaseIdProviderElement(root.evalNode("databaseIdProvider"));		//数据库类型和Java数据类型的转换		typeHandlerElement(root.evalNode("typeHandlers"));		//这个是对数据库增删改查的解析		mapperElement(root.evalNode("mappers"));	} catch (Exception e) {		throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);	}}

private void mapperElement(XNode parent) throws Exception {	if (parent != null) {			for (XNode child : parent.getChildren()) {			//解析<package name=""/>			if ("package".equals(child.getName())) {				String mapperPackage = child.getStringAttribute("name");				//包路径存到mapperRegistry中				configuration.addMappers(mapperPackage);			} else {				//解析<mapper url="" class="" resource=""></mapper>				String resource = child.getStringAttribute("resource");				String url = child.getStringAttribute("url");				String mapperClass = child.getStringAttribute("class");				if (resource != null && url == null && mapperClass == null) {					ErrorContext.instance().resource(resource);					//读取Mapper.xml文件					InputStream inputStream = Resources.getResourceAsStream(resource);					XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream,					configuration, resource, configuration.getSqlFragments());					mapperParser.parse();				} else if (resource == null && url != null && mapperClass == null) {					ErrorContext.instance().resource(url);					InputStream inputStream = Resources.getUrlAsStream(url);					XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream,					configuration, url, configuration.getSqlFragments());					mapperParser.parse();				} else if (resource == null && url == null && mapperClass != null) {					Class<?> mapperInterface = Resources.classForName(mapperClass);					configuration.addMapper(mapperInterface);				} else {					throw new BuilderException("A mapper element may only specify a url, resource or class, but not more than one.");				}			}		}	}}

public void parse() {	if (!configuration.isResourceLoaded(resource)) {		//解析所有的子标签		configurationElement(parser.evalNode("/mapper"));		configuration.addLoadedResource(resource);		//把namespace（接口类型）和工厂类绑定起来		bindMapperForNamespace();	}	parsePendingResultMaps();	parsePendingCacheRefs();	parsePendingStatements();} //这里面解析的是Mapper.xml的标签private void configurationElement(XNode context) {	try {		String namespace = context.getStringAttribute("namespace");		if (namespace == null || namespace.equals("")) {			throw new BuilderException("Mapper's namespace cannot be empty");		} 		builderAssistant.setCurrentNamespace(namespace);		//对其他命名空间缓存配置的引用		cacheRefElement(context.evalNode("cache-ref"));		//对给定命名空间的缓存配置		cacheElement(context.evalNode("cache"));		parameterMapElement(context.evalNodes("/mapper/parameterMap"));		//是最复杂也是最强大的元素，用来描述如何从数据库结果集中来加载对象		resultMapElements(context.evalNodes("/mapper/resultMap"));		//可被其他语句引用的可重用语句块		sqlElement(context.evalNodes("/mapper/sql"));		//获得MappedStatement对象(增删改查标签)		buildStatementFromContext(context.evalNodes("select|insert|update|delete"));	} catch (Exception e) {		throw new BuilderException("Error parsing Mapper XML. The XML location is '" + resource + "'. Cause: " + e, e);	}}//获得MappedStatement对象(增删改查标签)private void buildStatementFromContext(List<XNode> list) {	if (configuration.getDatabaseId() != null) {		buildStatementFromContext(list, configuration.getDatabaseId());	} 	buildStatementFromContext(list, null);}//获得MappedStatement对象(增删改查标签)private void buildStatementFromContext(List<XNode> list, String requiredDatabaseId) {	//循环增删改查标签	for (XNode context : list) {		final XMLStatementBuilder statementParser = new XMLStatementBuilder(configuration, builderAssistant, context, requiredDatabaseId);		try {			//解析insert/update/select/del中的标签			statementParser.parseStatementNode();		} catch (IncompleteElementException e) {			configuration.addIncompleteStatement(statementParser);		}	}}public void parseStatementNode() {	//在命名空间中唯一的标识符,可以被用来引用这条语句	String id = context.getStringAttribute("id");	//数据库厂商标识	String databaseId = context.getStringAttribute("databaseId");	if (!databaseIdMatchesCurrent(id, databaseId, this.requiredDatabaseId)) {		return;	} 	String nodeName = context.getNode().getNodeName();	SqlCommandType sqlCommandType =	SqlCommandType.valueOf(nodeName.toUpperCase(Locale.ENGLISH));	boolean isSelect = sqlCommandType == SqlCommandType.SELECT;	//flushCache和useCache都和二级缓存有关	//将其设置为true后,只要语句被调用,都会导致本地缓存和二级缓存被清空,默认值:false	boolean flushCache = context.getBooleanAttribute("flushCache", !isSelect);	//将其设置为 true 后，将会导致本条语句的结果被二级缓存缓存起来，默认值：对 select 元素为 true	boolean useCache = context.getBooleanAttribute("useCache", isSelect);	boolean resultOrdered = context.getBooleanAttribute("resultOrdered", false);	// Include Fragments before parsing	XMLIncludeTransformer includeParser = new XMLIncludeTransformer(configuration, builderAssistant);	includeParser.applyIncludes(context.getNode());	//会传入这条语句的参数类的完全限定名或别名	String parameterType = context.getStringAttribute("parameterType");	Class<?> parameterTypeClass = resolveClass(parameterType);	String lang = context.getStringAttribute("lang");	LanguageDriver langDriver = getLanguageDriver(lang);	// Parse selectKey after includes and remove them.	processSelectKeyNodes(id, parameterTypeClass, langDriver);	// Parse the SQL (pre: <selectKey> and <include> were parsed and removed)	KeyGenerator keyGenerator;	String keyStatementId = id + SelectKeyGenerator.SELECT_KEY_SUFFIX;	keyStatementId = builderAssistant.applyCurrentNamespace(keyStatementId, true);	if (configuration.hasKeyGenerator(keyStatementId)) {		keyGenerator = configuration.getKeyGenerator(keyStatementId);	} else {		keyGenerator = context.getBooleanAttribute("useGeneratedKeys", configuration.isUseGeneratedKeys() && SqlCommandType.INSERT.equals(sqlCommandType)) ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE;	} 	SqlSource sqlSource = langDriver.createSqlSource(configuration, context, parameterTypeClass);	StatementType statementType =	StatementType.valueOf(context.getStringAttribute("statementType",	StatementType.PREPARED.toString()));	Integer fetchSize = context.getIntAttribute("fetchSize");	Integer timeout = context.getIntAttribute("timeout");	String parameterMap = context.getStringAttribute("parameterMap");	//从这条语句中返回的期望类型的类的完全限定名或别名	String resultType = context.getStringAttribute("resultType");	Class<?> resultTypeClass = resolveClass(resultType);	//外部resultMap的命名引用	String resultMap = context.getStringAttribute("resultMap");	String resultSetType = context.getStringAttribute("resultSetType");	ResultSetType resultSetTypeEnum = resolveResultSetType(resultSetType);	String keyProperty = context.getStringAttribute("keyProperty");	String keyColumn = context.getStringAttribute("keyColumn");	String resultSets = context.getStringAttribute("resultSets");	builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType,	fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass,	resultSetTypeEnum, flushCache, useCache, resultOrdered,	keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets);}public MappedStatement addMappedStatement(	String id,	SqlSource sqlSource,	StatementType statementType,	SqlCommandType sqlCommandType,	Integer fetchSize,	Integer timeout,	String parameterMap,	Class<?> parameterType,	String resultMap,	Class<?> resultType,	ResultSetType resultSetType,	boolean flushCache,	boolean useCache,	boolean resultOrdered,	KeyGenerator keyGenerator,	String keyProperty,	String keyColumn,	String databaseId,	LanguageDriver lang,	String resultSets) {	if (unresolvedCacheRef) {		throw new IncompleteElementException("Cache-ref not yet resolved");	} 		id = applyCurrentNamespace(id, false);		boolean isSelect = sqlCommandType == SqlCommandType.SELECT;		MappedStatement.Builder statementBuilder = new MappedStatement.Builder(configuration,		id, sqlSource, sqlCommandType)		.resource(resource)		.fetchSize(fetchSize)		.timeout(timeout)		.statementType(statementType)		.keyGenerator(keyGenerator)		.keyProperty(keyProperty)		.keyColumn(keyColumn)		.databaseId(databaseId)		.lang(lang)		.resultOrdered(resultOrdered)		.resultSets(resultSets)		.resultMaps(getStatementResultMaps(resultMap, resultType, id))		.resultSetType(resultSetType)		.flushCacheRequired(valueOrDefault(flushCache, !isSelect))		.useCache(valueOrDefault(useCache, isSelect))		.cache(currentCache);		ParameterMap statementParameterMap = getStatementParameterMap(parameterMap,		parameterType, id);		if (statementParameterMap != null) {			statementBuilder.parameterMap(statementParameterMap);		} 		MappedStatement statement = statementBuilder.build();		//持有在configuration中		configuration.addMappedStatement(statement);		return statement;}public void addMappedStatement(MappedStatement ms){//ms.getId = mapper.UserMapper.getUserById//ms = MappedStatement等于每一个增删改查的标签的里的数据	mappedStatements.put(ms.getId(), ms);}//最终存放到mappedStatements中,mappedStatements存放的是一个个的增删改查protected final Map<String, MappedStatement> mappedStatements = new StrictMap<MappedStatement>("Mapped Statements collection").conflictMessageProducer((savedValue, targetValue) ->". please check " + savedValue.getResource() + " and " + targetValue.getResource());

private void bindMapperForNamespace() {	//当前Mapper的命名空间	String namespace = builderAssistant.getCurrentNamespace();	if (namespace != null) {		Class<?> boundType = null;		try {			//interface mapper.UserMapper这种			boundType = Resources.classForName(namespace);		} catch (ClassNotFoundException e) {		} 		if (boundType != null) {			if (!configuration.hasMapper(boundType)) {				configuration.addLoadedResource("namespace:" + namespace);				configuration.addMapper(boundType);			}		}	}}public <T> void addMapper(Class<T> type) {	mapperRegistry.addMapper(type);} public <T> void addMapper(Class<T> type) {	if (type.isInterface()) {		if (hasMapper(type)) {			throw new BindingException("Type " + type + " is already known to the MapperRegistry.");		} 		boolean loadCompleted = false;		try {			//接口类型(key)->工厂类			knownMappers.put(type, new MapperProxyFactory<>(type));			MapperAnnotationBuilder parser = new MapperAnnotationBuilder(config, type);			parser.parse();			loadCompleted = true;		} finally {			if (!loadCompleted) {				knownMappers.remove(type);			}		}	}}

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

SqlSession sqlSession = sqlSessionFactory.openSession();

public SqlSession openSession() {	//configuration中有默认赋值protected ExecutorType defaultExecutorType = ExecutorType.SIMPLE	return openSessionFromDataSource(configuration.getDefaultExecutorType(), null, false);}

<environments default="development">	<environment id="development">		<transactionManager type="JDBC"/>		<dataSource type="POOLED">			<property name="driver" value="${driver}"/>			<property name="url" value="${url}"/>			<property name="username" value="${username}"/>			<property name="password" value="${password}"/>		</dataSource>	</environment></environments>

//ExecutorType是SIMPLE,一共有三种SIMPLE(SimpleExecutor)、REUSE(ReuseExecutor)、BATCH(BatchExecutor)private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {	Transaction tx = null;	try {		//xml中的development节点		final Environment environment = configuration.getEnvironment();		//type配置的是Jbdc所以生成的是JbdcTransactionFactory工厂类		final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);		//Jdbc生成JbdcTransactionFactory生成JbdcTransaction		tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);		//创建CachingExecutor执行器		final Executor executor = configuration.newExecutor(tx, execType);		//创建DefaultSqlSession属性包括 Configuration、Executor对象		return new DefaultSqlSession(configuration, executor, autoCommit);	} catch (Exception e) {		closeTransaction(tx); // may have fetched a connection so lets call		close()		throw ExceptionFactory.wrapException("Error opening session. Cause: " + e, e);	} finally {		ErrorContext.instance().reset();	}}

UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

public <T> T getMapper(Class<T> type) {	return configuration.getMapper(type, this);}

public <T> T getMapper(Class<T> type, SqlSession sqlSession) {	return mapperRegistry.getMapper(type, sqlSession);}

public <T> T getMapper(Class<T> type, SqlSession sqlSession) {	final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>)	knownMappers.get(type);	if (mapperProxyFactory == null) {		throw new BindingException("Type " + type + " is not known to the MapperRegistry.");	} 	try {		return mapperProxyFactory.newInstance(sqlSession);	} catch (Exception e) {		throw new BindingException("Error getting mapper instance. Cause: " + e, e);	}}public T newInstance(SqlSession sqlSession) {	final MapperProxy<T> mapperProxy = new MapperProxy<>(sqlSession, mapperInterface, methodCache);	return newInstance(mapperProxy);}

protected T newInstance(MapperProxy<T> mapperProxy) {	//mapperInterface是interface mapper.UserMapper		return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new	Class[] { mapperInterface }, mapperProxy);}

UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

User user = userMapper.getUserById(1);

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {	try {		//判断是否需要去执行SQL还是直接执行方法		if (Object.class.equals(method.getDeclaringClass())) {			return method.invoke(this, args);			//这里判断的是接口中的默认方法Default等		} else if (isDefaultMethod(method)) {			return invokeDefaultMethod(proxy, method, args);		}	} catch (Throwable t) {		throw ExceptionUtil.unwrapThrowable(t);	}     //获取缓存,保存了方法签名和接口方法的关系	final MapperMethod mapperMethod = cachedMapperMethod(method);	return mapperMethod.execute(sqlSession, args);}

public Object execute(SqlSession sqlSession, Object[] args) {	Object result;	//根据命令类型走不行的操作command.getType()是select	switch (command.getType()) {		case INSERT: {			Object param = method.convertArgsToSqlCommandParam(args);			result = rowCountResult(sqlSession.insert(command.getName(), param));			break;		} 		case UPDATE: {			Object param = method.convertArgsToSqlCommandParam(args);			result = rowCountResult(sqlSession.update(command.getName(), param));			break;		} 		case DELETE: {			Object param = method.convertArgsToSqlCommandParam(args);			result = rowCountResult(sqlSession.delete(command.getName(), param));			break;		} 		case SELECT:			if (method.returnsVoid() && method.hasResultHandler()) {				executeWithResultHandler(sqlSession, args);				result = null;			} else if (method.returnsMany()) {				result = executeForMany(sqlSession, args);			} else if (method.returnsMap()) {				result = executeForMap(sqlSession, args);			} else if (method.returnsCursor()) {				result = executeForCursor(sqlSession, args);			} else {				//将参数转换为SQL的参数				Object param = method.convertArgsToSqlCommandParam(args);				result = sqlSession.selectOne(command.getName(), param);				if (method.returnsOptional()				&& (result == null ||				!method.getReturnType().equals(result.getClass()))) {					result = Optional.ofNullable(result);				}			}			break;		case FLUSH:			result = sqlSession.flushStatements();			break;		default:			throw new BindingException("Unknown execution method for: " + command.getName());	} 	if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid()) {		throw new BindingException("Mapper method '" + command.getName() + " attempted to return null from a method with a primitive return type (" + method.getReturnType() + ").");	} 	return result;}

public <T> T selectOne(String statement, Object parameter) {	// Popular vote was to return null on 0 results and throw exception on too many.	List<T> list = this.selectList(statement, parameter);	if (list.size() == 1) {		return list.get(0);	} else if (list.size() > 1) {		throw new TooManyResultsException("Expected one result (or null) to be returned by selectOne(), but found: " + list.size());	} else {		return null;	}}

public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) {	try {		//从Configuration里的mappedStatements里根据key(id的全路径)获取MappedStatement 对象		MappedStatement ms = configuration.getMappedStatement(statement);		return executor.query(ms, wrapCollection(parameter), rowBounds, Executor.NO_RESULT_HANDLER);	} catch (Exception e) {		throw ExceptionFactory.wrapException("Error querying database. Cause: " + e, e);	} finally {		ErrorContext.instance().reset();	}}

public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler) throws SQLException {	//创建缓存Key	BoundSql boundSql = ms.getBoundSql(parameterObject);	//key = -575461213:-771016147:mapper.UserMapper.getUserById:0:2147483647:select * from test_user where id = ?:1:development	CacheKey key = createCacheKey(ms, parameterObject, rowBounds, boundSql);	return query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);}

public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException {	Cache cache = ms.getCache();	if (cache != null) {		flushCacheIfRequired(ms);		if (ms.isUseCache() && resultHandler == null) {			ensureNoOutParams(ms, boundSql);			@SuppressWarnings("unchecked")			List<E> list = (List<E>) tcm.getObject(cache, key);			if (list == null) {				list = delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);				tcm.putObject(cache, key, list); // issue #578 and #116			} 			return list;		}	}	return delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);}

public <E> List<E> query(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException {	ErrorContext.instance().resource(ms.getResource()).activity("executing a query").object(ms.getId());	if (closed) {		throw new ExecutorException("Executor was closed.");	} 	//queryStack 用于记录查询栈，防止递归查询重复处理缓存	//flushCache=true 的时候，会先清理本地缓存（一级缓存）	if (queryStack == 0 && ms.isFlushCacheRequired()) {		//清空本地缓存		clearLocalCache();	} 	List<E> list;	try {		queryStack++;		list = resultHandler == null ? (List<E>) localCache.getObject(key) : null;		if (list != null) {			handleLocallyCachedOutputParameters(ms, key, parameter, boundSql);		} else {			//如果没有缓存,会从数据库查询：queryFromDatabase()			list = queryFromDatabase(ms, parameter, rowBounds, resultHandler, key, boundSql);		}	} finally {		queryStack--;	} 	if (queryStack == 0) {		for (DeferredLoad deferredLoad : deferredLoads) {		deferredLoad.load();		} 		// issue #601		deferredLoads.clear();		//如果 LocalCacheScope == STATEMENT,会清理本地缓存		if (configuration.getLocalCacheScope() == LocalCacheScope.STATEMENT) {			// issue #482			clearLocalCache();		}	} 	return list;}

private <E> List<E> queryFromDatabase(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException {	List<E> list;	//先在缓存用占位符占位	localCache.putObject(key, EXECUTION_PLACEHOLDER);	try {		//执行Executor 的 doQuery(),默认是SimpleExecutor		list = doQuery(ms, parameter, rowBounds, resultHandler, boundSql);	} finally {		//执行查询后,移除占位符		localCache.removeObject(key);	} 	//从新放入数据	localCache.putObject(key, list);	if (ms.getStatementType() == StatementType.CALLABLE) {		localOutputParameterCache.putObject(key, parameter);	} 	return list;}

public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {	Statement stmt = null;	try {		Configuration configuration = ms.getConfiguration();		StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);		stmt = prepareStatement(handler, ms.getStatementLog());		return handler.query(stmt, resultHandler);	} finally {		closeStatement(stmt);	}}