把sql都封装成一个个的statement ， 然后我们再去把namespace+id绑定一个代理的工厂 ， 后面用来调用 ， 最终也是调用的MapperRegistry.addMapper
public void parse() {// 总体上做了两件事情 ， 对于语句的注册和接口的注册if (!configuration.isResourceLoaded(resource)) {// 1、具体增删改查标签的解析 。// 一个标签一个MappedStatement 。configurationElement(parser.evalNode("/mapper"));configuration.addLoadedResource(resource);// 2、把namespace（接口类型）和工厂类绑定起来 ， 放到一个map 。// 一个namespace 一个 MapperProxyFactorybindMapperForNamespace();}parsePendingResultMaps();parsePendingCacheRefs();parsePendingStatements();}parse方法中的第一步configurationElement（）操作参考以下代码
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);// 添加缓存对象cacheRefElement(context.evalNode("cache-ref"));// 解析 cache 属性 ， 添加缓存对象cacheElement(context.evalNode("cache"));// 创建 ParameterMapping 对象parameterMapElement(context.evalNodes("/mapper/parameterMap"));// 创建 List<ResultMapping>resultMapElements(context.evalNodes("/mapper/resultMap"));// 解析可以复用的SQLsqlElement(context.evalNodes("/mapper/sql"));// 解析增删改查标签 ， 得到 MappedStatement 也是重要的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);}}private void buildStatementFromContext(List<XNode> list) {if (configuration.getDatabaseId() != null) {buildStatementFromContext(list, configuration.getDatabaseId());}// 解析 Statement list代表的是XXXMapper.xml中的所有的sql语句buildStatementFromContext(list, null);}private void buildStatementFromContext(List<XNode> list, String requiredDatabaseId) {for (XNode context : list) {// 用来解析增删改查标签的 XMLStatementBuilderfinal XMLStatementBuilder statementParser = new XMLStatementBuilder(configuration, builderAssistant, context, requiredDatabaseId);try {// 解析 Statement ， 添加 MappedStatement对象 详情看下方代码statementParser.parseStatementNode();} catch (IncompleteElementException e) {configuration.addIncompleteStatement(statementParser);}}}public void parseStatementNode() {String id = context.getStringAttribute("id");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;boolean flushCache = context.getBooleanAttribute("flushCache", !isSelect);boolean useCache = context.getBooleanAttribute("useCache", isSelect);boolean resultOrdered = context.getBooleanAttribute("resultOrdered", false);XMLIncludeTransformer includeParser = new XMLIncludeTransformer(configuration, builderAssistant);includeParser.applyIncludes(context.getNode());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");String resultType = context.getStringAttribute("resultType");Class<?> resultTypeClass = resolveClass(resultType);String resultMap = context.getStringAttribute("resultMap");String resultSetType = context.getStringAttribute("resultSetType");ResultSetType resultSetTypeEnum = resolveResultSetType(resultSetType);if (resultSetTypeEnum == null) {resultSetTypeEnum = configuration.getDefaultResultSetType();}String keyProperty = context.getStringAttribute("keyProperty");String keyColumn = context.getStringAttribute("keyColumn");String resultSets = context.getStringAttribute("resultSets");// 关键的一步： MappedStatement 的创建封装成MappedStatement对象//每一个sql变成一个MappedStatementbuilderAssistant.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");}//设置id是namespace+sqlId判断最终的sql标签是否重复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();// 最关键的一步 ， 在 Configuration 添加了 MappedStatementconfiguration.addMappedStatement(statement);return statement;}public void addMappedStatement(MappedStatement ms) {//Id 是namespace+sqlId 也是这个map中的key//key是 namespace+sqlId value是 MappedStatementmappedStatements.put(ms.getId(), ms);}