Mybatis源码阅读的关键点

Myth丶恋晨 2022-05-27 08:05 210阅读 0赞

阅读Mybatis源码时，随手下关键点，以备以后查看

解析过程如下：

XMLConfigBuilder.mapperElement ===> configuration.addMappers(mapperPackage);

MapperAnnotationBuilder.parse 解析注解的入口

MapperAnnotationBuilder.parseStatement 解析Mapper中的每个方法，形成MappedStatement

MapperAnnotationBuilder.getSqlSourceFromAnnotations 获取注解中的SQL语句

XMLLanguageDriver.createSqlSource 解析注解中SQL语句，替换$\{...\}占位符

PropertyParser.parse 解析语句中属性值（$\{...\}占位符）

SqlSourceBuilder.parse 解析语句中数据值\#\{...\}占位符

如果带IN查询SQL

@Select(value = \{ "<script>", "SELECT \* FROM \[USER\] WHERE ID IN ", "<foreach item='item' index='index' collection='ids' open='(' separator=',' close=')'>", "$\{item\}", "</foreach>", "</script>" \})

@Results(value = \{ @Result(column = "user\_name", property = "userName") \})

public List<String> getUserNameByIds(@Param("ids") List<Integer> ids);

解析过程如下：

XMLLanguageDriver.createSqlSource 使用XPathParser解析

XMLScriptBuilder.parseScriptNode Xml方式解析

XMLScriptBuilder.nodeHandlers 和 NodeHandler接口实现Xml节点解析

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:40px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("trim", new TrimHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("where", new WhereHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("set", new SetHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("foreach", new ForEachHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("if", new IfHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("choose", new ChooseHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("when", new IfHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("otherwise", new OtherwiseHandler());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> map.put("bind", new BindHandler());</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

2 解析mapper.xml

mapper有哪些节点：

cache-ref、cache、parameterMap、resultMap、sql、select|insert|update|delete

3 执行SQL Statement的过程

解析过程如下

DefaultSqlSession.selectOne/selectList/insert/delete... CRUD操作调用

CachingExecutor.query/update CRUD都会调用query/update方法

BoundSql.getBoundSql 解析SQL，填充数据

DynamicContext 是动态上下文，包括configuration和参数

GenericTokenParser解析SQL，替换SQL中的参数$\{...\}

TextSqlNode.handleToken 核心方法

$\{...\} 属性占位符，属于静态文本替换