终于要讲到mapper的解析了，这个地方是最重要的地方，日常大部分程序员的时间就在这里。

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stop in org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement

private void mapperElement(XNode parent) throws Exception {// 看到这里了if (parent != null) {// 开始遍历每1个节点for (XNode child : parent.getChildren()) {// 如果是package命名if ("package".equals(child.getName())) {String mapperPackage = child.getStringAttribute("name");configuration.addMappers(mapperPackage);} else {// 一般从这里开始执行// 获取resource的属性值String resource = child.getStringAttribute("resource");// 获取url的属性值String url = child.getStringAttribute("url");// 获取class的属性值String mapperClass = child.getStringAttribute("class");// 如果是指定了resource,其它都没有指定，就走这个分支if (resource != null && url == null && mapperClass == null) {// 看到这里了// 将文件路径保存到上下文中,ThreadLocal型ErrorContext.instance().resource(resource);// 读取文件流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.");}}}}}

org.apache.ibatis.builder.xml.XMLMapperBuilder.parse

进入parse函数后，先解决

parameterMapElement(context.evalNodes("/mapper/parameterMap"));

stop in org.apache.ibatis.builder.xml.XMLMapperBuilder.parameterMapElement

看到一半，朋友说这个parameterMap很少用，所以不需要看了。