课时 20:MyBatis架构和SqlSessionFactory源码分析

.1)分析mybatis的架构(四层架构)

　　1.接口层(广义接口)

　　　　1.1 增加接口方法 删除 增加 修改 查询 各种直接使用的配置方法

　　2.数据处理层

　　　　2.1 列如select * from student where name=#{} and age=#{}

　　　　　　2.1.1 首先处理参数

　　　　　　2.1.2 处理完参数 之后解析SQL

　　　　　　2.1.3 解析完SQL之后数据库就知道你要干嘛了 开始执行SQL(Executor)

　　　　　　2.1.4 执行完SQL 开始处理结果

　　3.框架支撑层

　　　　 3.1 事务管理 缓存机制 连接池管理等等(各种辅助功能)

　　4.引导层
　　　　 4.1 SQL语句的方式:XML配置 or 注解方式

.2)获取SqlSessionFactory源码分析　　

　　1.获取了一个parse解析器

XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);

　　2.通过configuration标签 设置了很多个子参数 properties丶settings丶typeAliases等等子标签

 this.parseConfiguration(this.parser.evalNode("/configuration"));

　　　　2.1 上面调用的方法如下

private void parseConfiguration(XNode root) {
        try {
            this.propertiesElement(root.evalNode("properties"));
            Properties settings = this.settingsAsProperties(root.evalNode("settings"));
            this.loadCustomVfs(settings);
            this.typeAliasesElement(root.evalNode("typeAliases"));
            this.pluginElement(root.evalNode("plugins"));
            this.objectFactoryElement(root.evalNode("objectFactory"));
            this.objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));
            this.reflectorFactoryElement(root.evalNode("reflectorFactory"));
            this.settingsElement(settings);
            this.environmentsElement(root.evalNode("environments"));
            this.databaseIdProviderElement(root.evalNode("databaseIdProvider"));
            this.typeHandlerElement(root.evalNode("typeHandlers"));
            this.mapperElement(root.evalNode("mappers"));
        } catch (Exception var3) {
            throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + var3, var3);
        }
    }

　　　　2.2 分析几个代表性的标签

　　　　　　2.2.1 settings分析

　　　　　　　　2.2.1.1 设置标签中通过settingsElment()方法 创建了很多子元素 并且带有默认值

private void settingsElement(Properties props) throws Exception {
        this.configuration.setAutoMappingBehavior(AutoMappingBehavior.valueOf(props.getProperty("autoMappingBehavior", "PARTIAL")));
        this.configuration.setAutoMappingUnknownColumnBehavior(AutoMappingUnknownColumnBehavior.valueOf(props.getProperty("autoMappingUnknownColumnBehavior", "NONE")));
        this.configuration.setCacheEnabled(this.booleanValueOf(props.getProperty("cacheEnabled"), true));
        this.configuration.setProxyFactory((ProxyFactory)this.createInstance(props.getProperty("proxyFactory")));
        this.configuration.setLazyLoadingEnabled(this.booleanValueOf(props.getProperty("lazyLoadingEnabled"), false));
        this.configuration.setAggressiveLazyLoading(this.booleanValueOf(props.getProperty("aggressiveLazyLoading"), false));
        this.configuration.setMultipleResultSetsEnabled(this.booleanValueOf(props.getProperty("multipleResultSetsEnabled"), true));
        this.configuration.setUseColumnLabel(this.booleanValueOf(props.getProperty("useColumnLabel"), true));
        this.configuration.setUseGeneratedKeys(this.booleanValueOf(props.getProperty("useGeneratedKeys"), false));
        this.configuration.setDefaultExecutorType(ExecutorType.valueOf(props.getProperty("defaultExecutorType", "SIMPLE")));
        this.configuration.setDefaultStatementTimeout(this.integerValueOf(props.getProperty("defaultStatementTimeout"), (Integer)null));
        this.configuration.setDefaultFetchSize(this.integerValueOf(props.getProperty("defaultFetchSize"), (Integer)null));
        this.configuration.setMapUnderscoreToCamelCase(this.booleanValueOf(props.getProperty("mapUnderscoreToCamelCase"), false));
        this.configuration.setSafeRowBoundsEnabled(this.booleanValueOf(props.getProperty("safeRowBoundsEnabled"), false));
        this.configuration.setLocalCacheScope(LocalCacheScope.valueOf(props.getProperty("localCacheScope", "SESSION")));
        this.configuration.setJdbcTypeForNull(JdbcType.valueOf(props.getProperty("jdbcTypeForNull", "OTHER")));
        this.configuration.setLazyLoadTriggerMethods(this.stringSetValueOf(props.getProperty("lazyLoadTriggerMethods"), "equals,clone,hashCode,toString"));
        this.configuration.setSafeResultHandlerEnabled(this.booleanValueOf(props.getProperty("safeResultHandlerEnabled"), true));
        this.configuration.setDefaultScriptingLanguage(this.resolveClass(props.getProperty("defaultScriptingLanguage")));
        Class<? extends TypeHandler> typeHandler = this.resolveClass(props.getProperty("defaultEnumTypeHandler"));
        this.configuration.setDefaultEnumTypeHandler(typeHandler);
        this.configuration.setCallSettersOnNulls(this.booleanValueOf(props.getProperty("callSettersOnNulls"), false));
        this.configuration.setUseActualParamName(this.booleanValueOf(props.getProperty("useActualParamName"), true));
        this.configuration.setReturnInstanceForEmptyRow(this.booleanValueOf(props.getProperty("returnInstanceForEmptyRow"), false));
        this.configuration.setLogPrefix(props.getProperty("logPrefix"));
        Class<? extends Log> logImpl = this.resolveClass(props.getProperty("logImpl"));
        this.configuration.setLogImpl(logImpl);
        this.configuration.setConfigurationFactory(this.resolveClass(props.getProperty("configurationFactory")));
    }

　　　　　　2.2.2 分析mappers分析

　　　　　　　　2.2.2.1 通过这个来分析不同的映射SQL映射文件

private void mapperElement(XNode parent) throws Exception {
        if (parent != null) {
            Iterator var2 = parent.getChildren().iterator();

            while(true) {
                while(var2.hasNext()) {
                    XNode child = (XNode)var2.next();
                    String resource;
                    if ("package".equals(child.getName())) {
                        resource = child.getStringAttribute("name");
                        this.configuration.addMappers(resource);
                    } else {
                        resource = child.getStringAttribute("resource");
                        String url = child.getStringAttribute("url");
                        String mapperClass = child.getStringAttribute("class");
                        XMLMapperBuilder mapperParser;
                        InputStream inputStream;
                        if (resource != null && url == null && mapperClass == null) {
                            ErrorContext.instance().resource(resource);
                            inputStream = Resources.getResourceAsStream(resource);
                            mapperParser = new XMLMapperBuilder(inputStream, this.configuration, resource, this.configuration.getSqlFragments());
                            mapperParser.parse();
                        } else if (resource == null && url != null && mapperClass == null) {
                            ErrorContext.instance().resource(url);
                            inputStream = Resources.getUrlAsStream(url);
                            mapperParser = new XMLMapperBuilder(inputStream, this.configuration, url, this.configuration.getSqlFragments());
                            mapperParser.parse();
                        } else {
                            if (resource != null || url != null || mapperClass == null) {
                                throw new BuilderException("A mapper element may only specify a url, resource or class, but not more than one.");
                            }

                            Class<?> mapperInterface = Resources.classForName(mapperClass);
                            this.configuration.addMapper(mapperInterface);
                        }
                    }
                }

                return;
            }
        }
    }

mapperParser.parse();

　　　　　　　　2.2.2.2 通过进一步的发现 开始解析SQL文件的增删改查操作

this.configurationElement(this.parser.evalNode("/mapper"));

　　　　　　　　2.2.2.3 通过上面的方法开始解析SQL映射文件

 this.buildStatementFromContext(context.evalNodes("select|insert|update|delete"));

　　　　　　　　2.2.2.4 parseStatementNode()方法来解析标签属性

public void parseStatementNode() {
        String id = this.context.getStringAttribute("id");
        String databaseId = this.context.getStringAttribute("databaseId");
        if (this.databaseIdMatchesCurrent(id, databaseId, this.requiredDatabaseId)) {
            Integer fetchSize = this.context.getIntAttribute("fetchSize");
            Integer timeout = this.context.getIntAttribute("timeout");
            String parameterMap = this.context.getStringAttribute("parameterMap");
            String parameterType = this.context.getStringAttribute("parameterType");
            Class<?> parameterTypeClass = this.resolveClass(parameterType);
            String resultMap = this.context.getString
Attribute("resultMap");
            String resultType = this.context.getStringAttribute("resultType");
            String lang = this.context.getStringAttribute("lang");
            LanguageDriver langDriver = this.getLanguageDriver(lang);
            Class<?> resultTypeClass = this.resolveClass(resultType);
            String resultSetType = this.context.getStringAttribute("resultSetType");
            StatementType statementType = StatementType.valueOf(this.context.getStringAttribute("statementType", StatementType.PREPARED.toString()));
            ResultSetType resultSetTypeEnum = this.resolveResultSetType(resultSetType);
            String nodeName = this.context.getNode().getNodeName();
            SqlCommandType sqlCommandType = SqlCommandType.valueOf(nodeName.toUpperCase(Locale.ENGLISH));
            boolean isSelect = sqlCommandType == SqlCommandType.SELECT;
            boolean flushCache = this.context.getBooleanAttribute("flushCache", !isSelect);
            boolean useCache = this.context.getBooleanAttribute("useCache", isSelect);
            boolean resultOrdered = this.context.getBooleanAttribute("resultOrdered", false);
            XMLIncludeTransformer includeParser = new XMLIncludeTransformer(this.configuration, this.builderAssistant);
            includeParser.applyIncludes(this.context.getNode());
            this.processSelectKeyNodes(id, parameterTypeClass, langDriver);
            SqlSource sqlSource = langDriver.createSqlSource(this.configuration, this.context, parameterTypeClass);
            String resultSets = this.context.getStringAttribute("resultSets");
            String keyProperty = this.context.getStringAttribute("keyProperty");
            String keyColumn = this.context.getStringAttribute("keyColumn");
            String keyStatementId = id + "!selectKey";
            keyStatementId = this.builderAssistant.applyCurrentNamespace(keyStatementId, true);
            Object keyGenerator;
            if (this.configuration.hasKeyGenerator(keyStatementId)) {
                keyGenerator = this.configuration.getKeyGenerator(keyStatementId);
            } else {
                keyGenerator = this.context.getBooleanAttribute("useGeneratedKeys", this.configuration.isUseGeneratedKeys() && SqlCommandType.INSERT.equals(sqlCommandType)) ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE;
            }
    //这个方法用于构建出一个statement对象
            this.builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType, fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass, resultSetTypeEnum, flushCache, useCache, resultOrdered, (KeyGenerator)keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets);
        }
    }

　　　　　　　　2.2.2.5 在解析完成会将select等标签封装成一个MappedStatement类

　　　　　　　　　　 即 MappedStatement就是select 标签

 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 (this.unresolvedCacheRef) {
            throw new IncompleteElementException("Cache-ref not yet resolved");
        } else {
            id = this.applyCurrentNamespace(id, false);
            boolean isSelect = sqlCommandType == SqlCommandType.SELECT;
            org.apache.ibatis.mapping.MappedStatement.Builder statementBuilder = (new org.apache.ibatis.mapping.MappedStatement.Builder(this.configuration, id, sqlSource, sqlCommandType)).resource(this.resource).fetchSize(fetchSize).timeout(timeout).statementType(statementType).keyGenerator(keyGenerator).keyProperty(keyProperty).keyColumn(keyColumn).databaseId(databaseId).lang(lang).resultOrdered(resultOrdered).resultSets(resultSets).resultMaps(this.getStatementResultMaps(resultMap, resultType, id)).resultSetType(resultSetType).flushCacheRequired((Boolean)this.valueOrDefault(flushCache, !isSelect)).useCache((Boolean)this.valueOrDefault(useCache, isSelect)).cache(this.currentCache);
            ParameterMap statementParameterMap = this.getStatementParameterMap(parameterMap, parameterType, id);
            if (statementParameterMap != null) {
                statementBuilder.parameterMap(statementParameterMap);
            }

            MappedStatement statement = statementBuilder.build();
            this.configuration.addMappedStatement(statement);
            return statement;
        }
    }

　　 3.MappedStatement --->存在于Configuration中 environment--->存在于Configuration中

　　　　所有的配置信息都存在于Configuration中

　　　　Configuration有存在于DefaultSqlSessionFactory对象中(SqlSessionFactory)-->SqlSessionFactory 多态的体现

　　4.结构

　　　　 4.1 SqlSessionFactory --> DefaultSqlSessionFactory-->Configuration-->包含了一切信息