【1】测试用例

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><!-- 1)properteis1.1、mybatis 可以使用properties 标签来引入外部properties配置文件的内容；1.2、resource 引入类路径下 的资源；1.3、url 是引入网络路径或磁盘路径下的资源；--><properties resource="dbconfig.properties"></properties><!-- 2)settings 包含很多重要的设置项2.1、setting 用来设置每一个设置项：name: 设置项名称， value：设置项取值；--><!-- 开启驼峰命名规则，数据库表字段 a_b 可以解析为 类成员变量 aB --><!-- 显示指定每个需要更改的配置项，即使有默认值，防止版本更新带来的问题 --><settings><!-- 开启驼峰命名法 --><setting name="mapUnderscoreToCamelCase" value="false"/><!-- 懒加载 --><setting name="lazyLoadingEnabled" value="true"/><!-- 侵入型懒加载 --><setting name="aggressiveLazyLoading" value="false"/></settings><!-- 3)别名处理器：可以为java类型起别名（注意：别名不区分大小写）3.1) typeAlias为某一个java类型取别名， type：指定要起别名的类型全类名，默认别名就是类名小写，employeealias: 指定新的 别名；3.3）--><typeAliases><!-- 3.1) typeAlias为某一个java类型取别名， type：指定要起别名的类型全类名，默认别名就是类名小写，employeealias: 指定新的 别名；<typeAlias type="com.swjtu.mybatis.bean.Employee" alias="emp"/>--><!-- 3.2)package: 为某个包下的所有类批量起别名:name: 指定包名，为当前包以及所有的子包的每个类都起一个默认别名（类名小写）；--><!-- 3.3) 批量起别名的情况下，可以使用注解 Alias()为某个类型指定新的别名；存在 a 包 和 a.b 包下都有 Employee类的情况；--><package name="com.swjtu.mybatis.bean"/></typeAliases><!-- 4、environments： 环境们， mybatis可以配置多种环境， default指定使用某种环境。可以达到快速切换环境。4.1)environment：配置一个具体的环境信息；必须有两个标签：id代表当前环境的唯一标识4.1.1) transactionManager 必须有， 事务管理器，type 事务管理器类型，type="[JDBC|MANAGED]" 自定义事务管理器：实现 TransactionFactory 接口， type指定全类名 Configuration类中定义了别名： org.apache.ibatis.session.ConfigurationtypeAliasRegistry.registerAlias("JDBC", JdbcTransactionFactory.class);typeAliasRegistry.registerAlias("MANAGED", ManagedTransactionFactory.class);4.1.2) dataSource 数据源：type：数据源类型 type="[UNPOOLED|POOLED|JNDI]"typeAliasRegistry.registerAlias("JNDI", JndiDataSourceFactory.class);typeAliasRegistry.registerAlias("POOLED", PooledDataSourceFactory.class);typeAliasRegistry.registerAlias("UNPOOLED", UnpooledDataSourceFactory.class);自定义数据源： 实现 DataSourceFactory 接口 ， type 为自定义数据源的全类名                                           -->                        <environments default="development"><!-- 测试环境 --><environment id="test"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="${jdbc.driver}"/><property name="url" value="${jdbc.url}"/><property name="username" value="${jdbc.username}"/><property name="password" value="${jdbc.password}"/></dataSource></environment><!-- 开发环境 --><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="${jdbc.driver}"/><property name="url" value="${jdbc.url}"/><property name="username" value="${jdbc.username}"/><property name="password" value="${jdbc.password}"/></dataSource></environment></environments><!-- 5、databaseIdProvider ：支持多数据库厂商的；type=DB_VENDOR: VendorDatabaseIdProvider作用就是得到数据库厂商标识（由数据库驱动自己附带的 getDatabaseProductName），mybatis根据该标识执行不同的sql；并在 sql 标签如<select> 添加属性 databaseId 属性--> <databaseIdProvider type="DB_VENDOR"><!-- 为不同数据库厂商起别名 --><property name="Mysql" value="mysql"/><property name="Oracle" value="oracle"/><property name="SQL Server" value="sqlserver"/></databaseIdProvider> <!-- 将我们写好的sql 映射文件 EmployeeMapper.xml 一定要注册到全局配置文件 mybatis-config.xml 中；6、mappers：将sql映射注册到全局配置中；--> <mappers><!-- mapper标签： 注册一个sql映射注册配置文件的两种方法：方法1：resource： 引用类路径下的sql 映射文件；方法2：url： 引用网络路径或磁盘路径下的 sql 映射文件；注册接口的方法：方法1 class： 直接引用（注册）接口， 写接口的全类名；补充1：  有sql映射文件，映射文件名必须和接口同名，并且仿造同一个目录下；补充2： 没有sql映射文件， 所有sql 利用注解修饰接口上；补充3： 不推荐使用注解，而使用sql映射文件的方式来 进行sql 映射。--><mapper resource="com\swjtu\mybatis\dao\EmployeeMapper.xml"/> <!-- 批量注册： 前提是要把 Mapper类文件和Mapper sql 映射文件放在同目录下荔枝：<package name="com.swjtu.mybatis.dao"/> 可以吧 该包下的所有mapper 映射文件注册到全局配置环境中；--><!-- <mapper class="com.swjtu.mybatis.dao.cwn.MYCwnOprDAO"/> --></mappers></configuration>

执行sql；

public static void main1() {/*1. 获取 SqlSessionFactory 对象*/SqlSessionFactory sqlSessionFactory = MyBatisUtils.getSqlSessionFactory();/*2.获取SqlSession对象, 不会自动提交数据*/SqlSession session = sqlSessionFactory.openSession();try { String flag = "0911A"; List<Map<String, Object>> list = new ArrayList<>();for (int i = 0; i < 5; i++) {  String indexFormat = String.format("%8d", i);Map<String, Object> map = new HashMap<>(); map.put("RCRD_ID", flag + indexFormat); map.put("CUST_NUM", "CUST_NUM" +flag+ indexFormat);map.put("CUST_NAME", "CUST_NAME" +flag+ indexFormat);map.put("WARN_TIMES", i); list.add(map); }
//          mapper.insert2CustWarn(list);session.insert("com.swjtu.mybatis.dao.EmployeeMapper.insert2CustWarn", list); session.commit();} finally { session.close();}System.out.println("bingo!");}

mapper文件中的 dml 元素
<insert id="insert2CustWarn">INSERT INTO my_cust_warn_tbl(rcrd_id, cust_num, cust_name , warn_times) VALUES <foreach collection="list" item="item" separator=",">(#{item.RCRD_ID}, #{item.CUST_NUM}, #{item.CUST_NAME}, #{item.WARN_TIMES})</foreach></insert>

MyBatisUtils.getSqlSessionFactory();

/*** 获取SqlSessionFactory * @return*/
public final static SqlSessionFactory getSqlSessionFactory() {String resource = "mybatis-config.xml";InputStream inputStream;try { inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);return sqlSessionFactory;} catch (IOException e) {e.printStackTrace();}return null;
}

【2】创建 SqlSessionFactory 对象

SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

实际上返回的是 DefaultSqlSessionFactory；

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

而 build(Configuration config) 中的 config 是从mybatis-config.xml文件解析而来的；

【2.1】XMLConfigBuilder.parse() 产生Configuration

parser.parse() 方法的逻辑如下（XMLConfigBuilder构造器中新建了 Configuration对象）：

// SqlSessionFactoryBuilder
private XMLConfigBuilder(XPathParser parser, String environment, Properties props) {super(new Configuration());// 新建了一个 configuration对象ErrorContext.instance().resource("SQL Mapper Configuration");this.configuration.setVariables(props);this.parsed = false;this.environment = environment;this.parser = parser;}public Configuration parse() {if (parsed) {throw new BuilderException("Each XMLConfigBuilder can only be used once.");}parsed = true;parseConfiguration(parser.evalNode("/configuration"));// 解析xml节点return configuration;}private void parseConfiguration(XNode root) {// 解析xml节点try {Properties settings = settingsAsPropertiess(root.evalNode("settings"));//issue #117 read properties firstpropertiesElement(root.evalNode("properties"));loadCustomVfs(settings);typeAliasesElement(root.evalNode("typeAliases"));pluginElement(root.evalNode("plugins"));objectFactoryElement(root.evalNode("objectFactory"));objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));reflectorFactoryElement(root.evalNode("reflectorFactory"));settingsElement(settings);// read it after objectFactory and objectWrapperFactory issue #631environmentsElement(root.evalNode("environments"));databaseIdProviderElement(root.evalNode("databaseIdProvider"));typeHandlerElement(root.evalNode("typeHandlers"));mapperElement(root.evalNode("mappers"));} catch (Exception e) {throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);}}

我们跟踪了 mapperElement(..) 方法，它是解析 mybatis-config.xml 文件中在 mapper标签中配置的resource属性指定的sql mapper文件，比如：

<mappers>               <mapper resource="com\swjtu\mybatis\dao\EmployeeMapper.xml"/>     <mapper class="com.swjtu.mybatis.dao.EmployeeMapperAnnotation"/>
</mappers>

其中 root.evalNode("mappers") 获取的值就是 mapper 数组；

private void mapperElement(XNode parent) throws Exception {if (parent != null) {for (XNode child : parent.getChildren()) {if ("package".equals(child.getName())) {String mapperPackage = child.getStringAttribute("name");configuration.addMappers(mapperPackage);} else {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);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.");}}}}}

Xnode parent 长这样（就是 mybatis-config.xml 中 mappers元素内容）：

以上代码，我们发现，解析 mapper有三种方式；

1.通过resource 配置；
2.通过url；
3.通过mapper class；

下面，我们以resource 为例来讲解；

if (resource != null && url == null && mapperClass == null) {ErrorContext.instance().resource(resource);InputStream inputStream = Resources.getResourceAsStream(resource);XMLMapperBuilder mapperParser = new XMLMapperBuilder
(inputStream, configuration, resource, configuration.getSqlFragments());mapperParser.parse();
}

以上代码发现，每一个mapper文件，都会创建一个 XMLMapperBuilder 对象来解析它；

String resource=“com\swjtu\mybatis\dao\EmployeeMapper.xml”;

XMLMapperBuilder构造器传入了4个参数

mapper文件的输入流（com\swjtu\mybatis\dao\EmployeeMapper.xml文件流）；
mybatis配置对象Configuration；
resource（sql文件名称com\swjtu\mybatis\dao\EmployeeMapper.xml）；
sqlFragments-sql片段为空；

XMLMapperBuilder构造器；该构造器新建了 MapperBuilderAssistant对象（解析mapper文件的助手）；

public XMLMapperBuilder(InputStream inputStream, Configuration configuration, String resource, Map<String, XNode> sqlFragments) {this(new XPathParser(inputStream, true, configuration.getVariables(), new XMLMapperEntityResolver()),configuration, resource, sqlFragments);}private XMLMapperBuilder(XPathParser parser, Configuration configuration, String resource, Map<String, XNode> sqlFragments) {super(configuration);this.builderAssistant = new MapperBuilderAssistant(configuration, resource);this.parser = parser;this.sqlFragments = sqlFragments;this.resource = resource;}

MapperBuilderAssistant() 长这个样子；

【2.2】XmlMapperBuilder().parse() 解析mappers下的每个mapper文件内容

接着，进入 XmlMapperBuilder().parse() 方法，解析mappers下的mapper元素的内容，mapper元素如 <mapper resource="com\swjtu\mybatis\dao\EmployeeMapper.xml"/> ；如下：

代码步骤：

step1）解析mapper文件下 mapper元素内容（主要是 dml标签元素内容）；
step2）把mapper文件名添加到 configuration，以避免二次解析；
step3）构建命名空间；

【2.2.1】 XmlMapperBuilder.configurationElement(parser.evalNode("/mapper"))如下：

其中 parser.evalNode("/mapper")或context就是文件 com\swjtu\mybatis\dao\EmployeeMapper.xml 的内容，如下：

代码步骤：

step1）设置命名空间；
step2）解析缓存；
step3）解析 parameterMap 标签内容；
step4）解析 resultMap 标签内容；
step5）解析 sql 标签内容；
step6）解析 sql 的dml 标签内容（select或insert或update 或 delete）；

最后一步， buildStatementFromContext(context.evalNodes("select|insert|update|delete")); 就是真正解析 sql的 dml语句的标签了，即解析出sql文本并加载到内存中；

List<XNode> list 包含了多个 dml标签的内容数组；

接着 buildStatementFromContext(List<XNode> list, String requiredDatabaseId) 遍历list中的每个dml 标签元素；如下：

private void buildStatementFromContext(List<XNode> list) {if (configuration.getDatabaseId() != null) {buildStatementFromContext(list, configuration.getDatabaseId());}buildStatementFromContext(list, null);}private void buildStatementFromContext(List<XNode> list, String requiredDatabaseId) {for (XNode context : list) {final XMLStatementBuilder statementParser = new XMLStatementBuilder(configuration, builderAssistant, context, requiredDatabaseId);try {statementParser.parseStatementNode();} catch (IncompleteElementException e) {configuration.addIncompleteStatement(statementParser);}}}

以上代码，每个 dml标签元素就会创建一个 XMLStatementBuilder 对象；

statementParser.parseStatementNode();

就用于解析 context 文本（dml标签元素内容）；如下：

public void parseStatementNode() {String id = context.getStringAttribute("id");String databaseId = context.getStringAttribute("databaseId");if (!databaseIdMatchesCurrent(id, databaseId, this.requiredDatabaseId)) {return;}Integer fetchSize = context.getIntAttribute("fetchSize");Integer timeout = context.getIntAttribute("timeout");String parameterMap = context.getStringAttribute("parameterMap");String parameterType = context.getStringAttribute("parameterType");Class<?> parameterTypeClass = resolveClass(parameterType);String resultMap = context.getStringAttribute("resultMap");String resultType = context.getStringAttribute("resultType");String lang = context.getStringAttribute("lang");LanguageDriver langDriver = getLanguageDriver(lang);Class<?> resultTypeClass = resolveClass(resultType);String resultSetType = context.getStringAttribute("resultSetType");StatementType statementType = StatementType.valueOf(context.getStringAttribute("statementType", StatementType.PREPARED.toString()));ResultSetType resultSetTypeEnum = resolveResultSetType(resultSetType);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);// Include Fragments before parsingXMLIncludeTransformer includeParser = new XMLIncludeTransformer(configuration, builderAssistant);includeParser.applyIncludes(context.getNode());// Parse selectKey after includes and remove them.processSelectKeyNodes(id, parameterTypeClass, langDriver);// Parse the SQL (pre: <selectKey> and <include> were parsed and removed)SqlSource sqlSource = langDriver.createSqlSource(configuration, context, parameterTypeClass);String resultSets = context.getStringAttribute("resultSets");String keyProperty = context.getStringAttribute("keyProperty");String keyColumn = context.getStringAttribute("keyColumn");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))? new Jdbc3KeyGenerator() : new NoKeyGenerator();}builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType,fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass,resultSetTypeEnum, flushCache, useCache, resultOrdered, keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets);}

以上代码的步骤如下：

step1）解析 dml元素中各种属性，包括 parameterMap，parameterType，resultMap，resultType等；

Integer fetchSize = context.getIntAttribute("fetchSize");Integer timeout = context.getIntAttribute("timeout");String parameterMap = context.getStringAttribute("parameterMap");String parameterType = context.getStringAttribute("parameterType");Class<?> parameterTypeClass = resolveClass(parameterType);String resultMap = context.getStringAttribute("resultMap");String resultType = context.getStringAttribute("resultType");

resultType 为map；因为 dml标签元素如下：

<select id="getEmpByLastNameLikeReturnMap" resultType="map">SELECT id AS ID, last_name AS LASTNAME, email AS EMAIL, gender AS GENDERFROM emp_tbl WHERE last_name like #{lastName}</select>

step2）获取语言驱动器， LanguageDriver langDriver = getLanguageDriver(lang);

step3） Class<?> resultTypeClass = resolveClass(resultType);：返回 resultType的class类型；如 resultType为map，则返回 Map.class ;

protected Class<?> resolveClass(String alias) { // 以alias为map为例if (alias == null) {return null;}try {return resolveAlias(alias);} catch (Exception e) {throw new BuilderException("Error resolving class. Cause: " + e, e);}}
// BaseBuilder.java
protected Class<?> resolveAlias(String alias) {return typeAliasRegistry.resolveAlias(alias);}public <T> Class<T> resolveAlias(String string) {try {if (string == null) {return null;}// issue #748String key = string.toLowerCase(Locale.ENGLISH);Class<T> value;if (TYPE_ALIASES.containsKey(key)) {value = (Class<T>) TYPE_ALIASES.get(key);} else {value = (Class<T>) Resources.classForName(string);}return value;} catch (ClassNotFoundException e) {throw new TypeException("Could not resolve type alias '" + string + "'.  Cause: " + e, e);}}

typeAliasRegistry 为类型别名注册器，如下：

public TypeAliasRegistry() {registerAlias("string", String.class);registerAlias("byte", Byte.class);registerAlias("long", Long.class);registerAlias("short", Short.class);registerAlias("int", Integer.class);registerAlias("integer", Integer.class);registerAlias("double", Double.class);registerAlias("float", Float.class);registerAlias("boolean", Boolean.class);registerAlias("byte[]", Byte[].class);registerAlias("long[]", Long[].class);registerAlias("short[]", Short[].class);registerAlias("int[]", Integer[].class);registerAlias("integer[]", Integer[].class);registerAlias("double[]", Double[].class);registerAlias("float[]", Float[].class);registerAlias("boolean[]", Boolean[].class);registerAlias("_byte", byte.class);registerAlias("_long", long.class);registerAlias("_short", short.class);registerAlias("_int", int.class);registerAlias("_integer", int.class);registerAlias("_double", double.class);registerAlias("_float", float.class);registerAlias("_boolean", boolean.class);registerAlias("_byte[]", byte[].class);registerAlias("_long[]", long[].class);registerAlias("_short[]", short[].class);registerAlias("_int[]", int[].class);registerAlias("_integer[]", int[].class);registerAlias("_double[]", double[].class);registerAlias("_float[]", float[].class);registerAlias("_boolean[]", boolean[].class);registerAlias("date", Date.class);registerAlias("decimal", BigDecimal.class);registerAlias("bigdecimal", BigDecimal.class);registerAlias("biginteger", BigInteger.class);registerAlias("object", Object.class);registerAlias("date[]", Date[].class);registerAlias("decimal[]", BigDecimal[].class);registerAlias("bigdecimal[]", BigDecimal[].class);registerAlias("biginteger[]", BigInteger[].class);registerAlias("object[]", Object[].class);registerAlias("map", Map.class);registerAlias("hashmap", HashMap.class);registerAlias("list", List.class);registerAlias("arraylist", ArrayList.class);registerAlias("collection", Collection.class);registerAlias("iterator", Iterator.class);registerAlias("ResultSet", ResultSet.class);}

step4）获取sql语句类型， PREPARED ；

step5）获取sql命令类型 SqlCommandType -SELECT

String nodeName = context.getNode().getNodeName(); // nodeName为selectSqlCommandType sqlCommandType = SqlCommandType.valueOf(nodeName.toUpperCase(Locale.ENGLISH));public enum SqlCommandType {UNKNOWN, INSERT, UPDATE, DELETE, SELECT, FLUSH;
}

step6）解析是否需要使用缓存

boolean flushCache = context.getBooleanAttribute("flushCache", !isSelect);//false
boolean useCache = context.getBooleanAttribute("useCache", isSelect);//true
boolean resultOrdered = context.getBooleanAttribute("resultOrdered", false);//false

step7）解析dml元素中 include元素内容（比如 include sql）；

 XMLIncludeTransformer includeParser = new XMLIncludeTransformer(configuration, builderAssistant);includeParser.applyIncludes(context.getNode());

public void applyIncludes(Node source) {Properties variablesContext = new Properties();Properties configurationVariables = configuration.getVariables();if (configurationVariables != null) {variablesContext.putAll(configurationVariables);}applyIncludes(source, variablesContext);}

step8）解析 selectKey；sql中没有，不用考虑；

processSelectKeyNodes(id, parameterTypeClass, langDriver);

step9）创建sql 映射对象；

SqlSource sqlSource = langDriver.createSqlSource(configuration, context, parameterTypeClass);

langDriver 指向了 org.apache.ibatis.scripting.xmltags.XMLLanguageDriver；

public class XMLLanguageDriver implements LanguageDriver {@Overridepublic ParameterHandler createParameterHandler(MappedStatement mappedStatement, Object parameterObject, BoundSql boundSql) {return new DefaultParameterHandler(mappedStatement, parameterObject, boundSql);}@Overridepublic SqlSource createSqlSource(Configuration configuration, XNode script, Class<?> parameterType) {XMLScriptBuilder builder = new XMLScriptBuilder(configuration, script, parameterType);return builder.parseScriptNode();}@Overridepublic SqlSource createSqlSource(Configuration configuration, String script, Class<?> parameterType) {// issue #3if (script.startsWith("<script>")) {XPathParser parser = new XPathParser(script, false, configuration.getVariables(), new XMLMapperEntityResolver());return createSqlSource(configuration, parser.evalNode("/script"), parameterType);} else {// issue #127script = PropertyParser.parse(script, configuration.getVariables());TextSqlNode textSqlNode = new TextSqlNode(script);if (textSqlNode.isDynamic()) {return new DynamicSqlSource(configuration, textSqlNode);} else {return new RawSqlSource(configuration, script, parameterType);}}}}

builder.parseScriptNode() 调用的是 XMLScriptBuilder.parseScriptNode() ；解析动态sql （用${} 包裹的sql ）；

 public SqlSource parseScriptNode() {List<SqlNode> contents = parseDynamicTags(context);MixedSqlNode rootSqlNode = new MixedSqlNode(contents);SqlSource sqlSource = null;if (isDynamic) {sqlSource = new DynamicSqlSource(configuration, rootSqlNode);} else {sqlSource = new RawSqlSource(configuration, rootSqlNode, parameterType);}return sqlSource;}List<SqlNode> parseDynamicTags(XNode node) {List<SqlNode> contents = new ArrayList<SqlNode>();NodeList children = node.getNode().getChildNodes();for (int i = 0; i < children.getLength(); i++) {XNode child = node.newXNode(children.item(i));if (child.getNode().getNodeType() == Node.CDATA_SECTION_NODE || child.getNode().getNodeType() == Node.TEXT_NODE) {String data = child.getStringBody("");TextSqlNode textSqlNode = new TextSqlNode(data);if (textSqlNode.isDynamic()) {contents.add(textSqlNode);isDynamic = true;} else {contents.add(new StaticTextSqlNode(data));}} else if (child.getNode().getNodeType() == Node.ELEMENT_NODE) { // issue #628String nodeName = child.getNode().getNodeName();NodeHandler handler = nodeHandlers(nodeName);if (handler == null) {throw new BuilderException("Unknown element <" + nodeName + "> in SQL statement.");}handler.handleNode(child, contents);isDynamic = true;}}return contents;}

因为我们不是动态sql，所以返回的是 RawSqlSource；

sqlSource = new RawSqlSource(configuration, rootSqlNode, parameterType);

step10）解析 resultSets， keyProperty， keyColumn 属性等（也不用太关心）；

String resultSets = context.getStringAttribute("resultSets");String keyProperty = context.getStringAttribute("keyProperty");String keyColumn = context.getStringAttribute("keyColumn");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))? new Jdbc3KeyGenerator() : new NoKeyGenerator();}

step11）MapperBuilderAssistant.addMappedStatement() 把解析得到的sql映射对象添加到configuration；

builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType,fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass,resultSetTypeEnum, flushCache, useCache, resultOrdered, keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets);

参数列表如下：

1.id，getEmpByLastNameLikeReturnMap；
2.sqlSource，

parameterMappins 明显是参数映射；

3.statementType ， PREPARED；
4.sqlCommandType，SELECT;
5.fetchSize，null；
6.timeout， null；
7.parameterMap，null；
8.parameterTypeClass，null；
9.resultMap，null；
10.resultTypeClass， interface java.util.Map；
11.resultSetTypeEnum，null；
12.flushCache，false；
13.useCache，true；
14.resultOrdered，false；
15.keyGenerator，org.apache.ibatis.executor.keygen.NoKeyGenerator@5ef8df1e；
16.keyProperty，null；
17.keyColumn，null；
18.databaseId，null；
19.langDriver， org.apache.ibatis.scripting.xmltags.XMLLanguageDriver@32057e6；
20.resultSets, null；

MapperBuilderAssistant.addMappedStatement(...) 源码如下：

public MappedStatement addMappedStatement(...) {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();configuration.addMappedStatement(statement);return statement;}

id = applyCurrentNamespace(id, false); 这一步，给id添加命名空间前缀，

执行前；id为 getEmpByLastNameLikeReturnMap ；
执行后，id为 com.swjtu.mybatis.dao.EmployeeMapper.getEmpByLastNameLikeReturnMap；

解析每个dml元素时，都要创建一个 MappedStatement.Builder(...) 用于创建 MappedStatement（ sql映射信息）

MappedStatement.Builder statementBuilder = new MappedStatement.Builder(configuration, id, sqlSource, sqlCommandType)

MappedStatement statement = statementBuilder.build(); 源码如下：

public MappedStatement build() {assert mappedStatement.configuration != null;assert mappedStatement.id != null;assert mappedStatement.sqlSource != null;assert mappedStatement.lang != null;mappedStatement.resultMaps = Collections.unmodifiableList(mappedStatement.resultMaps);return mappedStatement;}

补充：MappedStatement对象

MappedStatement 实际是封装了 sql映射信息的对象，sql映射是在 MapperBuilderAssistant.addMappedStatement(...) 方法里面构建；结构如下：

每条sql都是一个 MappedStatement对象，解析完成后，将其添加到 configuration对象中；

configuration 就是根据mybatis-config.xml 文件解析出的 Configuration 对象；长这个样子：

【2.2.2】 configuration.addLoadedResource(resource);

把已经解析的resource 文件名添加到 configuration，避免二次解析；

【2.2.3】XMLMapperBuilder.bindMapperForNamespace() 创建命名空间

private void bindMapperForNamespace() {String namespace = builderAssistant.getCurrentNamespace();if (namespace != null) {Class<?> boundType = null;try {boundType = Resources.classForName(namespace);} catch (ClassNotFoundException e) {//ignore, bound type is not required}if (boundType != null) {if (!configuration.hasMapper(boundType)) {// Spring may not know the real resource name so we set a flag// to prevent loading again this resource from the mapper interface// look at MapperAnnotationBuilder#loadXmlResourceconfiguration.addLoadedResource("namespace:" + namespace);configuration.addMapper(boundType);}}}}public <T> void addMapper(Class<T> type) {mapperRegistry.addMapper(type);}

很显然，当有mapperclass的时候，才会设置 boundType；如果没有mapper class也没有关系；因为catch会忽略异常；

【2.2.4】解析其他

 parsePendingResultMaps();parsePendingChacheRefs();parsePendingStatements();

【2.2.5】创建 DefaultSqlSession对象并返回

解析完成后，生成Configuration对象;

【3】sqlSessionFactory.openSession()打开会话

调用的是 DefaultSqlSessionFactory.openSession()

// DefaultSqlSessionFactory
@Overridepublic SqlSession openSession() {return openSessionFromDataSource(configuration.getDefaultExecutorType(), null, false);}private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {Transaction tx = null;try {final Environment environment = configuration.getEnvironment();final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);final Executor executor = configuration.newExecutor(tx, execType);// 返回的是  DefaultSqlSession 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();}}

【3.1】DefaultSqlSessionFactory 中有两类方法包括，

从数据源获取会话：private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit)；
从连接中获取会话：private SqlSession openSessionFromConnection(ExecutorType execType, Connection connection) ；

两者不同点在于

tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);

final Transaction tx = transactionFactory.newTransaction(connection);

// 从数据源获取会话
private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {Transaction tx = null;try {final Environment environment = configuration.getEnvironment();final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);// 创建事务工厂tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);// 创建事务 final Executor executor = configuration.newExecutor(tx, execType);// 执行器 return new DefaultSqlSession(configuration, executor, autoCommit);// 会话} 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();}}// 从数据库连接获取会话 private SqlSession openSessionFromConnection(ExecutorType execType, Connection connection) {try {boolean autoCommit;try {autoCommit = connection.getAutoCommit();} catch (SQLException e) {// Failover to true, as most poor drivers// or databases won't support transactionsautoCommit = true;}      final Environment environment = configuration.getEnvironment();final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);final Transaction tx = transactionFactory.newTransaction(connection);final Executor executor = configuration.newExecutor(tx, execType);return new DefaultSqlSession(configuration, executor, autoCommit);} catch (Exception e) {throw ExceptionFactory.wrapException("Error opening session.  Cause: " + e, e);} finally {ErrorContext.instance().reset();}}

获取会话无论采用 datasource，还是connection方式，其步骤如下：

step1）获取环境对象；
step2）获取事务工厂；
step3）创建事务；
step4）创建执行器；
step5）创建会话 DefaultSqlSession；

【3.2】事务工厂

// 从环境对象中获取事务工厂private TransactionFactory getTransactionFactoryFromEnvironment(Environment environment) {if (environment == null || environment.getTransactionFactory() == null) {return new ManagedTransactionFactory();}return environment.getTransactionFactory();}

如果配置了环境元素，则返回配置的环境的事务工厂；否则默认返回 ManagedTransactionFactory；

此外，事务工厂有3个，如下：

【3.3】创建事务-ManagedTransaction

// 可管理的事务工厂
public class ManagedTransactionFactory implements TransactionFactory {private boolean closeConnection = true;@Overridepublic void setProperties(Properties props) {if (props != null) {String closeConnectionProperty = props.getProperty("closeConnection");if (closeConnectionProperty != null) {closeConnection = Boolean.valueOf(closeConnectionProperty);}}}@Overridepublic Transaction newTransaction(Connection conn) {return new ManagedTransaction(conn, closeConnection);}
// 创建事务对象@Overridepublic Transaction newTransaction(DataSource ds, TransactionIsolationLevel level, boolean autoCommit) {// Silently ignores autocommit and isolation level, as managed transactions are entirely// controlled by an external manager.  It's silently ignored so that// code remains portable between managed and unmanaged configurations.return new ManagedTransaction(ds, level, closeConnection);}
}

可管理事务： ManagedTransaction；

public class ManagedTransaction implements Transaction {private static final Log log = LogFactory.getLog(ManagedTransaction.class);private DataSource dataSource;private TransactionIsolationLevel level;private Connection connection;private boolean closeConnection;public ManagedTransaction(Connection connection, boolean closeConnection) {this.connection = connection;this.closeConnection = closeConnection;}public ManagedTransaction(DataSource ds, TransactionIsolationLevel level, boolean closeConnection) {this.dataSource = ds;this.level = level;this.closeConnection = closeConnection;}@Overridepublic Connection getConnection() throws SQLException {if (this.connection == null) {openConnection();}return this.connection;}@Overridepublic void commit() throws SQLException {// Does nothing}@Overridepublic void rollback() throws SQLException {// Does nothing}@Overridepublic void close() throws SQLException {if (this.closeConnection && this.connection != null) {if (log.isDebugEnabled()) {log.debug("Closing JDBC Connection [" + this.connection + "]");}this.connection.close();}}protected void openConnection() throws SQLException {if (log.isDebugEnabled()) {log.debug("Opening JDBC Connection");}this.connection = this.dataSource.getConnection();if (this.level != null) {this.connection.setTransactionIsolation(this.level.getLevel());}}}

它的commit， rollback 都是空的；

它的数据库连接的获取有两种方式，

上游给定，传入 Connection ;
通过 datasource 数据源获取connection；

【3.4】创建执行器

1）ExecutorType 是枚举类型，默认为SIMPLE ；

final Executor executor = configuration.newExecutor(tx, execType);// Configuration.newExecutor 方法
public Executor newExecutor(Transaction transaction, ExecutorType executorType) {executorType = executorType == null ? defaultExecutorType : executorType;executorType = executorType == null ? ExecutorType.SIMPLE : executorType;Executor executor;if (ExecutorType.BATCH == executorType) {executor = new BatchExecutor(this, transaction);} else if (ExecutorType.REUSE == executorType) {executor = new ReuseExecutor(this, transaction);} else {executor = new SimpleExecutor(this, transaction);}if (cacheEnabled) {executor = new CachingExecutor(executor);}executor = (Executor) interceptorChain.pluginAll(executor);return executor;}

如果为SIMPLE,则返回 SimpleExecutor 执行器；但如果启用缓存，则封装SimpleExecutor到缓存执行器；

最后把执行器添加到拦截器列表，拦截器 Interceptor 列表如下，本质上是一个 ArrayList数组；

// 拦截器
public class InterceptorChain {private final List<Interceptor> interceptors = new ArrayList<Interceptor>();public Object pluginAll(Object target) {for (Interceptor interceptor : interceptors) {target = interceptor.plugin(target);}return target;}public void addInterceptor(Interceptor interceptor) {interceptors.add(interceptor);}public List<Interceptor> getInterceptors() {return Collections.unmodifiableList(interceptors);}}

其中SimpleExecutor父类Executor的实现类包括

2）SimpleExecutor 长这个样子

public class SimpleExecutor extends BaseExecutor {public SimpleExecutor(Configuration configuration, Transaction transaction) {super(configuration, transaction);}@Overridepublic int doUpdate(MappedStatement ms, Object parameter) throws SQLException {Statement stmt = null;try {Configuration configuration = ms.getConfiguration();StatementHandler handler = configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, null, null);stmt = prepareStatement(handler, ms.getStatementLog());return handler.update(stmt);} finally {closeStatement(stmt);}}@Overridepublic <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.<E>query(stmt, resultHandler);} finally {closeStatement(stmt);}}@Overrideprotected <E> Cursor<E> doQueryCursor(MappedStatement ms, Object parameter, RowBounds rowBounds, BoundSql boundSql) throws SQLException {Configuration configuration = ms.getConfiguration();StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, null, boundSql);Statement stmt = prepareStatement(handler, ms.getStatementLog());return handler.<E>queryCursor(stmt);}@Overridepublic List<BatchResult> doFlushStatements(boolean isRollback) throws SQLException {return Collections.emptyList();}private Statement prepareStatement(StatementHandler handler, Log statementLog) throws SQLException {Statement stmt;Connection connection = getConnection(statementLog);stmt = handler.prepare(connection, transaction.getTimeout());handler.parameterize(stmt);return stmt;}}

【3.5】创建会话 DefaultSqlSession

 public DefaultSqlSession(Configuration configuration, Executor executor, boolean autoCommit) {this.configuration = configuration;this.executor = executor;this.dirty = false;this.autoCommit = autoCommit;}

【4】session.insert(...)

【4.1】DefaultSqlSession.insert()

session.insert(...); 它实际调用的是 DefaultSqlSession.insert() 方法；

// DefaultSqlSession
@Overridepublic int insert(String statement, Object parameter) {return update(statement, parameter);}@Overridepublic int update(String statement) {return update(statement, null);}@Overridepublic int update(String statement, Object parameter) {try {dirty = true;MappedStatement ms = configuration.getMappedStatement(statement);return executor.update(ms, wrapCollection(parameter));} catch (Exception e) {throw ExceptionFactory.wrapException("Error updating database.  Cause: " + e, e);} finally {ErrorContext.instance().reset();}}

executor.update(ms, warpCollection(parameter)); 中的 executor是 SimpleExecutor;

我们接着看下 SimpleExecutor-执行器；

// 简单执行器
public class SimpleExecutor extends BaseExecutor {public SimpleExecutor(Configuration configuration, Transaction transaction) {super(configuration, transaction);}// 执行器基类
public abstract class BaseExecutor implements Executor {private static final Log log = LogFactory.getLog(BaseExecutor.class);protected Transaction transaction;protected Executor wrapper;protected ConcurrentLinkedQueue<DeferredLoad> deferredLoads;protected PerpetualCache localCache;protected PerpetualCache localOutputParameterCache;protected Configuration configuration;protected int queryStack = 0;private boolean closed;protected BaseExecutor(Configuration configuration, Transaction transaction) {this.transaction = transaction;this.deferredLoads = new ConcurrentLinkedQueue<DeferredLoad>();this.localCache = new PerpetualCache("LocalCache");this.localOutputParameterCache = new PerpetualCache("LocalOutputParameterCache");this.closed = false;this.configuration = configuration;this.wrapper = this;}

BaseExecutor.update(MappedStatement ms, Object parameter) 如下：

@Overridepublic int update(MappedStatement ms, Object parameter) throws SQLException {ErrorContext.instance().resource(ms.getResource()).activity("executing an update").object(ms.getId());if (closed) {throw new ExecutorException("Executor was closed.");}clearLocalCache();return doUpdate(ms, parameter);}

SimpleExecutor.doUpdate(...)

 @Overridepublic int doUpdate(MappedStatement ms, Object parameter) throws SQLException {Statement stmt = null;try {Configuration configuration = ms.getConfiguration();StatementHandler handler = configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, null, null);stmt = prepareStatement(handler, ms.getStatementLog());return handler.update(stmt);} finally {closeStatement(stmt);}}

上述是执行sql 语句的地方，依赖的对象包括：

configuration：根据mybatis-config.xml 解析得到的配置对象；
StatementHandler：语句处理器；
PreparedStatement：预编译语句；

Configuration.newStatementHandler(...) 方法如下：

  public StatementHandler newStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {StatementHandler statementHandler = new RoutingStatementHandler(executor, mappedStatement, parameterObject, rowBounds, resultHandler, boundSql);statementHandler = (StatementHandler) interceptorChain.pluginAll(statementHandler);return statementHandler;}

参数列表为：

参数1-executor；

参数2-mappedStatement；

参数3-parameterObject；

参数4- parameterObject 为：

{collection=[{RCRD_ID=0908A       0,CUST_NUM=CUST_NUM       0,WARN_TIMES=0,CUST_NAME=CUST_NAME       0},{RCRD_ID=0908A       1,CUST_NUM=CUST_NUM       1,WARN_TIMES=1,CUST_NAME=CUST_NAME       1},{RCRD_ID=0908A       2,CUST_NUM=CUST_NUM       2,WARN_TIMES=2,CUST_NAME=CUST_NAME       2},...],list=[{RCRD_ID=0908A       0,CUST_NUM=CUST_NUM       0,WARN_TIMES=0,CUST_NAME=CUST_NAME       0},{RCRD_ID=0908A       1,CUST_NUM=CUST_NUM       1,WARN_TIMES=1,CUST_NAME=CUST_NAME       1},{RCRD_ID=0908A       2,CUST_NUM=CUST_NUM       2,WARN_TIMES=2,CUST_NAME=CUST_NAME       2},]}

参数5-rowBounds

参数6-resultHandler 为null；

参数7-boundSql 为null ；

SimpleExecutor.newStatementHandler(...) 如下：

delegate = new PreparedStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);

代码步骤：

step1）获取mybatis 配置对象；

step2）获取 StatementHandler；

StatementHandler handler = configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, null, null);

StatementHandler handler =
configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, null, null);// 新建语句处理器public StatementHandler newStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {StatementHandler statementHandler = new RoutingStatementHandler(executor, mappedStatement, parameterObject, rowBounds, resultHandler, boundSql);statementHandler = (StatementHandler) interceptorChain.pluginAll(statementHandler);return statementHandler;}

step3）prepareStatement(StatementHandler handler, Log statementLog) ，把预编译sql 的参数赋值；

handler 为 PreparedStatementHandler ；

step3.1）stmt = handler.prepare(connection, transaction.getTimeout()); 获取预编译语句；

// RoutingStatementHandler @Overridepublic Statement prepare(Connection connection, Integer transactionTimeout) throws SQLException {return delegate.prepare(connection, transactionTimeout);}// BaseStatemetnHandler@Overridepublic Statement prepare(Connection connection, Integer transactionTimeout) throws SQLException {ErrorContext.instance().sql(boundSql.getSql());Statement statement = null;try {statement = instantiateStatement(connection);setStatementTimeout(statement, transactionTimeout);setFetchSize(statement);return statement;} catch (SQLException e) {closeStatement(statement);throw e;} catch (Exception e) {closeStatement(statement);throw new ExecutorException("Error preparing statement.  Cause: " + e, e);}}

step3.2）handler.parameterize(stmt); 对参数进行赋值；

// RoutingStatementHandler@Overridepublic void parameterize(Statement statement) throws SQLException {delegate.parameterize(statement);}// PreparedStatementHandler
@Overridepublic void parameterize(Statement statement) throws SQLException {parameterHandler.setParameters((PreparedStatement) statement);}//

parameterHandler.setParameters(...) ；源码如下：

遍历 sql语句中所有参数，并赋值；

public void setParameters(PreparedStatement ps) {ErrorContext.instance().activity("setting parameters").object(mappedStatement.getParameterMap().getId());List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();if (parameterMappings != null) {for (int i = 0; i < parameterMappings.size(); i++) {ParameterMapping parameterMapping = parameterMappings.get(i);if (parameterMapping.getMode() != ParameterMode.OUT) {Object value;String propertyName = parameterMapping.getProperty();if (boundSql.hasAdditionalParameter(propertyName)) { // issue #448 ask first for additional paramsvalue = boundSql.getAdditionalParameter(propertyName);} else if (parameterObject == null) {value = null;} else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {value = parameterObject;} else {MetaObject metaObject = configuration.newMetaObject(parameterObject);value = metaObject.getValue(propertyName);}TypeHandler typeHandler = parameterMapping.getTypeHandler();JdbcType jdbcType = parameterMapping.getJdbcType();if (value == null && jdbcType == null) {jdbcType = configuration.getJdbcTypeForNull();}try {typeHandler.setParameter(ps, i + 1, value, jdbcType);} catch (TypeException e) {throw new TypeException("Could not set parameters for mapping: " + parameterMapping + ". Cause: " + e, e);} catch (SQLException e) {throw new TypeException("Could not set parameters for mapping: " + parameterMapping + ". Cause: " + e, e);}}}

parameterMappings 是参数信息，如CUST_NUM ；

boundsql 是预编译sql，带有问号；

设置参数；

step4）handler.update() 执行具体 sql；

@Overridepublic int update(Statement statement) throws SQLException {return delegate.update(statement);}
// delegate 代理为 PreparedStatementHandler

执行具体sql，如下：

@Overridepublic int update(Statement statement) throws SQLException {PreparedStatement ps = (PreparedStatement) statement;ps.execute();  // 执行sql int rows = ps.getUpdateCount();  // 获取更新行数 Object parameterObject = boundSql.getParameterObject();KeyGenerator keyGenerator = mappedStatement.getKeyGenerator();keyGenerator.processAfter(executor, mappedStatement, ps, parameterObject);return rows;}

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mybatis-启动源码分析

【1】测试用例

【2】创建 SqlSessionFactory 对象

【2.1】XMLConfigBuilder.parse() 产生Configuration

【2.2】XmlMapperBuilder().parse() 解析mappers下的每个mapper文件内容

【2.2.1】 XmlMapperBuilder.configurationElement(parser.evalNode("/mapper"))如下：

补充：MappedStatement对象

【2.2.2】 configuration.addLoadedResource(resource);

【2.2.3】XMLMapperBuilder.bindMapperForNamespace() 创建命名空间

【2.2.4】解析其他

【2.2.5】创建 DefaultSqlSession对象并返回

【3】sqlSessionFactory.openSession()打开会话

【3.1】DefaultSqlSessionFactory 中有两类方法包括，

【3.2】事务工厂

【3.3】创建事务-ManagedTransaction

【3.4】创建执行器

【3.5】创建会话 DefaultSqlSession

【4】session.insert(...)

【4.1】DefaultSqlSession.insert()

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mybatis-启动源码分析

【1】测试用例

【2】创建 SqlSessionFactory 对象

【2.1】XMLConfigBuilder.parse() 产生Configuration

【2.2】XmlMapperBuilder().parse() 解析mappers下的每个mapper文件内容

【2.2.1】 XmlMapperBuilder.configurationElement(parser.evalNode("/mapper"))如下：

补充：MappedStatement对象

【2.2.2】 configuration.addLoadedResource(resource);

【2.2.3】XMLMapperBuilder.bindMapperForNamespace() 创建命名空间

【2.2.4】解析其他

【2.2.5】创建 DefaultSqlSession对象并返回

【3】sqlSessionFactory.openSession()打开会话

【3.1】DefaultSqlSessionFactory 中有两类方法包括，

【3.2】事务工厂

【3.3】创建事务-ManagedTransaction

【3.4】创建执行器

【3.5】 创建会话 DefaultSqlSession

【4】session.insert(...)

【4.1】DefaultSqlSession.insert()

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【3.5】创建会话 DefaultSqlSession