Mapper 接口方法如何与注解里的 SQL 进行绑定的？

﹏ヽ暗。殇╰゛Y 2022-12-13 01:25 87阅读 0赞

*  根据 Mapper 接口、其方法、方法上的注解，生成 mappedStatementId 与 MapperStatement，注册到 configuration 对象中
 *  根据 Mapper 接口方法查到并调用对应的 MappedStatement，执行 SQL

流程与 [Mapper 接口与 xml 绑定][Mapper _ xml]类似。

**分析**

解析生成注册 MapperStatement 的代码入口在 MapperRegistry addMapper 方法

//使用 MapperProxyFactory 包装 Mapper 接口 Class 对象
    knownMappers.put(type, new MapperProxyFactory<>(type));
    
    //解析 Mapper 接口方法上的注解，生成对应的 MapperStatement
    MapperAnnotationBuilder parser = new MapperAnnotationBuilder(config, type);
    parser.parse();

获取 Mapper 接口的动态代理对象的代码入口在 MapperRegistry getMapper 方法

public <T> T getMapper(Class<T> type, SqlSession sqlSession) {
        final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>) knownMappers.get(type);
        if (mapperProxyFactory == null) {
            throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
        }
        try {
            return mapperProxyFactory.newInstance(sqlSession);
        } catch (Exception e) {
            throw new BindingException("Error getting mapper instance. Cause: " + e, e);
        }
    }

--------------------

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[Mapper _ xml]: http://mp.weixin.qq.com/s?__biz=MzU1ODg0NjM2NA==&mid=2247484919&idx=1&sn=6d8d3d082afee17870d37c22031586bc&chksm=fc211d04cb56941244742e45420a025c734c2f89e13b7b31123d26f2516d55dd6a7c00d2710a&scene=21#wechat_redirect
[Link 1]: https://www.javanav.com/interview/93b0069472fd479393006c0e73043fc4.html
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[MySQL]: https://www.javanav.com/interview/d311e78502a845f1a4bb307bd6aec2b3.html
[Oracle]: https://www.javanav.com/interview/5f29e9677edf4a16be3dce30d257c9ab.html
[Redis]: https://www.javanav.com/interview/066c62b3af4d4827b2243a822c3084a9.html
[Dubbo]: https://www.javanav.com/interview/9a3e7a7740324757abaab953f7ebc455.html