Mybatis的Mapper代理对象生成及调用过程示例详解

if (this.mapperLocations != null) {
      if (this.mapperLocations.length == 0) {
        LOGGER.warn(() -> "Property 'mapperLocations' was specified but matching resources are not found.");
      } else {
        for (Resource mapperLocation : this.mapperLocations) {
          if (mapperLocation == null) {
            continue;
          }
          try {
            XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(mapperLocation.getInputStream(),
                targetConfiguration, mapperLocation.toString(), targetConfiguration.getSqlFragments());
            xmlMapperBuilder.parse();
          } catch (Exception e) {
            throw new NestedIOException("Failed to parse mapping resource: '" + mapperLocation + "'", e);
          } finally {
            ErrorContext.instance().reset();
          }
          LOGGER.debug(() -> "Parsed mapper file: '" + mapperLocation + "'");
        }
      }
    } else {
      LOGGER.debug(() -> "Property 'mapperLocations' was not specified.");
    }
    return this.sqlSessionFactoryBuilder.build(targetConfiguration);

private void configurationElement(XNode context) {
    try {
      //获取namespace
      String namespace = context.getStringAttribute("namespace");
      if (namespace == null || namespace.isEmpty()) {
        throw new BuilderException("Mapper's namespace cannot be empty");
      }
      builderAssistant.setCurrentNamespace(namespace);
    //二级缓存Ref解析
      cacheRefElement(context.evalNode("cache-ref"));
   //二级缓存配置的解析
      cacheElement(context.evalNode("cache"));
  //parameterMap标签的解析 
parameterMapElement(context.evalNodes("/mapper/parameterMap"));
   //resultMap标签的解析 
resultMapElements(context.evalNodes("/mapper/resultMap"));
   //sql标签的解析 
sqlElement(context.evalNodes("/mapper/sql"));
    //关键部分：sql语句的解析 
buildStatementFromContext(context.evalNodes("select|insert|update|delete"));
    } catch (Exception e) {
      throw new BuilderException("Error parsing Mapper XML. The XML location is '" + resource + "'. Cause: " + e, e);
    }
  }

MappedStatement statement = statementBuilder.build();
    configuration.addMappedStatement(statement);
    return statement;

@Override
  public <T> T getMapper(Class<T> type) {
    return getConfiguration().getMapper(type, this);
  }

public <T> T getMapper(Class<T> type, SqlSession sqlSession) {
    return mapperRegistry.getMapper(type, sqlSession);
  }

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);
    }
  }

protected T newInstance(MapperProxy<T> mapperProxy) {
    return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[] { mapperInterface }, mapperProxy);
  }
  public T newInstance(SqlSession sqlSession) {
    final MapperProxy<T> mapperProxy = new MapperProxy<>(sqlSession, mapperInterface, methodCache);
    return newInstance(mapperProxy);
  }

public Object invoke(Object proxy, Method method, Object[] args, SqlSession sqlSession) throws Throwable {
      return mapperMethod.execute(sqlSession, args);
    }