MyBatis源码的学习（7）---MappedStatement的的创建

最新推荐文章于 2025-07-09 21:28:44 发布

itw_zhangzx02

最新推荐文章于 2025-07-09 21:28:44 发布

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分类专栏： Mybatis源码学习

本文链接：https://blog.youkuaiyun.com/itw_zhangzx02/article/details/103560199

本文深入探讨了如何通过SqlSessionFactoryBuilder、XMLConfigBuilder、XMLMapperBuilder等逐步构建MappedStatement。详细解析了mapper.xml文件的抽象过程，包括mapperParser.parse()和buildStatementFromContext()方法，以及DynamicSqlSource与RawSqlSource在处理动态SQL和静态SQL的区别。同时，提到了动态标签如<where>,<foreach>,<trim>的解析逻辑。" 1925199,178118,使用JDBC处理Oracle CLOB字段,"['jdbc', '数据库操作', 'Oracle数据库', 'CLOB类型', 'Java编程']

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SqlSessionFactoryBuilder--->XMLConfigBuilder---> XMLMapperBuilder---(桥梁)MapperBuilderAssistant--->XMLStatementBuilder(parseStatementNode方法)--(桥梁)MapperBuilderAssistant（addMappedStatement方法）-->MappedStatement.Builder--->MappedStatement--->confuguration.addMappedStatement（）

sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);


public Configuration parse() {
    if (parsed) {
      throw new BuilderException("Each XMLConfigBuilder can only be used once.");
    }
    parsed = true;
    parseConfiguration(parser.evalNode("/configuration"));
    return configuration;
  }




private void parseConfiguration(XNode root) {
    try {
      //issue #117 read properties first
      propertiesElement(root.evalNode("properties"));
      Properties settings = settingsAsProperties(root.evalNode("settings"));
      loadCustomVfs(settings);
      loadCustomLogImpl(settings);
      typeAliasesElement(root.evalNode("typeAliases"));
      pluginElement(root.evalNode("plugins"));
      objectFactoryElement(root.evalNode("objectFactory"));
      objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));
      reflectorFactoryElement(root.evalNode("reflectorFactory"));
      //这一步，根据setting解析的结果，设置我们的一些参数，如果没有设置则给默认值。
      //我们的配置如下：
        /**
           <settings>
             <setting name="cacheEnabled" value="false"/>
             <setting name="logImpl" value="STDOUT_LOGGING" />
           </settings>
        */
      settingsElement(settings);
      // read it after objectFactory and objectWrapperFactory issue #631
      environmentsElement(root.evalNode("environments"));
      databaseIdProviderElement(root.evalNode("databaseIdProvider"));
      typeHandlerElement(root.evalNode("typeHandlers"));
      //这一步，解析Mapper.xml
      mapperElement(root.evalNode("mappers"));
    } catch (Exception e) {
      throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);
    }
  }

/**
<mappers>
    <mapper resource="userMapper.xml"/>    
</mappers>

*/
private void mapperElement(XNode parent) throws Exception {
    if (parent != null) {
      for (XNode child : parent.getChildren()) {
        if ("package".equals(child.getName())) {//子节点 是<package>这样的
          String mapperPackage = child.getStringAttribute("name");
          configuration.addMappers(mapperPackage);
        } else {//我们在这个分支 ，先获取 resource，url，class这三个属性的值
        //我们的resource值为：userMapper.xml
        //这三个属性值，只能三选一。
          String resource = child.getStringAttribute("resource");
          String url = child.getStringAttribute("url");
          String mapperClass = child.getStringAttribute("class");
          if (resource != null && url == null && mapperClass == null) {
         //我们在这个分支
            ErrorContext.instance().resource(resource);
            //读取我们的userMapper.xml文件，转为输入流
            InputStream inputStream = Resources.getResourceAsStream(resource);
            //创建XMLMapper的Builder对象
            XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream, configuration, resource, configuration.getSqlFragme