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mybatis-执行sql流程

时间:2022-11-27 19:56:07浏览次数:49  
标签:return 流程 Object ms sql mybatis null parameter method

一、获取mapper代理对象
DefaultSqlSession.getMapper(Class type)

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

Configuration.getMapper(Class type, SqlSession sqlSession)

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

MapperRegistry.getMapper(Class type, SqlSession 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);
    }
  }

MapperProxyFactory获取mapper代理对象。

MapperProxyFactory.newInstance(SqlSession sqlSession)

public T newInstance(SqlSession sqlSession) {
    final MapperProxy<T> mapperProxy = new MapperProxy<>(sqlSession, mapperInterface, methodCache);
    return newInstance(mapperProxy);
  }

MapperProxyFactory.newInstance(MapperProxy mapperProxy)

  protected T newInstance(MapperProxy<T> mapperProxy) {
    return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[] { mapperInterface }, mapperProxy);
  }

返回jdk动态代理。可知回调是MapperProxy类型。

二、执行流程
当通过mapper执行sql时,会执行动态代理的流程去执行查询。拿userMapper.selectUser(1)举例。
MapperProxy.invoke(Object proxy, Method method, Object[] args)

  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    try {
      if (Object.class.equals(method.getDeclaringClass())) {
        return method.invoke(this, args);
      } else {
        return cachedInvoker(method).invoke(proxy, method, args, sqlSession);
      }
    } catch (Throwable t) {
      throw ExceptionUtil.unwrapThrowable(t);
    }
  }

如果执行Object的方法则调用方法即可。否则调用cachedInvoker创建代理对象执行。

MapperProxy.cachedInvoker(Method method)

  private MapperMethodInvoker cachedInvoker(Method method) throws Throwable {
    try {
      return MapUtil.computeIfAbsent(methodCache, method, m -> {
        if (m.isDefault()) {
          try {
            if (privateLookupInMethod == null) {
              return new DefaultMethodInvoker(getMethodHandleJava8(method));
            } else {
              return new DefaultMethodInvoker(getMethodHandleJava9(method));
            }
          } catch (IllegalAccessException | InstantiationException | InvocationTargetException
              | NoSuchMethodException e) {
            throw new RuntimeException(e);
          }
        } else {
          return new PlainMethodInvoker(new MapperMethod(mapperInterface, method, sqlSession.getConfiguration()));
        }
      });
    } catch (RuntimeException re) {
      Throwable cause = re.getCause();
      throw cause == null ? re : cause;
    }
  }

如果在methodCache通过method找不到对应的MapperMethodInvoker则执行后面的lamda表达式。找到则返回。如果是默认方法则返回DefaultMethodInvoker。否则创建PlainMethodInvoker。

MapperMethod(Class<?> mapperInterface, Method method, Configuration config)

 public MapperMethod(Class<?> mapperInterface, Method method, Configuration config) {
    this.command = new SqlCommand(config, mapperInterface, method);
    this.method = new MethodSignature(config, mapperInterface, method);
  }

SqlCommand记录了执行方法的全路径和sql执行类型。MethodSignature记录了执行的方法的返回值属性,参数名解析等。

SqlCommand(Configuration configuration, Class<?> mapperInterface, Method method)

public SqlCommand(Configuration configuration, Class<?> mapperInterface, Method method) {
  final String methodName = method.getName();
  final Class<?> declaringClass = method.getDeclaringClass();
  MappedStatement ms = resolveMappedStatement(mapperInterface, methodName, declaringClass,
      configuration);
  if (ms == null) {
    if (method.getAnnotation(Flush.class) != null) {
      name = null;
      type = SqlCommandType.FLUSH;
    } else {
      throw new BindingException("Invalid bound statement (not found): "
          + mapperInterface.getName() + "." + methodName);
    }
  } else {
    name = ms.getId();
    type = ms.getSqlCommandType();
    if (type == SqlCommandType.UNKNOWN) {
      throw new BindingException("Unknown execution method for: " + name);
    }
  }
}

1、resolveMappedStatement获取MappedStatement,从configuration的mappedStatements获取MappedStatement。
2、如果MappedStatement为null,如果方法上有Flush注解,则设置执行类型为SqlCommandType.FLUSH。否则抛出异常。
3、如果MappedStatement不为null,设置类全名+方法名作为name,sql执行类型为type。

MethodSignature(Configuration configuration, Class<?> mapperInterface, Method method)

public MethodSignature(Configuration configuration, Class<?> mapperInterface, Method method) {
  Type resolvedReturnType = TypeParameterResolver.resolveReturnType(method, mapperInterface);
  if (resolvedReturnType instanceof Class<?>) {
    this.returnType = (Class<?>) resolvedReturnType;
  } else if (resolvedReturnType instanceof ParameterizedType) {
    this.returnType = (Class<?>) ((ParameterizedType) resolvedReturnType).getRawType();
  } else {
    this.returnType = method.getReturnType();
  }
  this.returnsVoid = void.class.equals(this.returnType);
  this.returnsMany = configuration.getObjectFactory().isCollection(this.returnType) || this.returnType.isArray();
  this.returnsCursor = Cursor.class.equals(this.returnType);
  this.returnsOptional = Optional.class.equals(this.returnType);
  this.mapKey = getMapKey(method);
  this.returnsMap = this.mapKey != null;
  this.rowBoundsIndex = getUniqueParamIndex(method, RowBounds.class);
  this.resultHandlerIndex = getUniqueParamIndex(method, ResultHandler.class);
  this.paramNameResolver = new ParamNameResolver(configuration, method);
}

记录了返回类型的信息及属性。paramNameResolver是参数名解析器。paramNameResolver将所有参数构造成参数下标为key,参数名为value的map保存在names集合中。

ParamNameResolver(Configuration config, Method method)

  public ParamNameResolver(Configuration config, Method method) {
    this.useActualParamName = config.isUseActualParamName();
    final Class<?>[] paramTypes = method.getParameterTypes();
    final Annotation[][] paramAnnotations = method.getParameterAnnotations();
    final SortedMap<Integer, String> map = new TreeMap<>();
    int paramCount = paramAnnotations.length;
    // get names from @Param annotations
    for (int paramIndex = 0; paramIndex < paramCount; paramIndex++) {
      if (isSpecialParameter(paramTypes[paramIndex])) {
        // skip special parameters
        continue;
      }
      String name = null;
      for (Annotation annotation : paramAnnotations[paramIndex]) {
        if (annotation instanceof Param) {
          hasParamAnnotation = true;
          name = ((Param) annotation).value();
          break;
        }
      }
      if (name == null) {
        // @Param was not specified.
        if (useActualParamName) {
          name = getActualParamName(method, paramIndex);
        }
        if (name == null) {
          // use the parameter index as the name ("0", "1", ...)
          // gcode issue #71
          name = String.valueOf(map.size());
        }
      }
      map.put(paramIndex, name);
    }
    names = Collections.unmodifiableSortedMap(map);
  }

遍历方法上的所有参数,如果参数有@Param,则获取@Param中的value作为参数名,如果参数没有@Param且useActualParamName为true获取方法实际参数名作为参数名。否则使用参数所在的下标作为参数名。并将参数所在下标为key,参数名为value加入names中。

PlainMethodInvoker.invoke(Object proxy, Method method, Object[] args, SqlSession sqlSession)

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

MapperMethod.execute(SqlSession sqlSession, Object[] args)

  public Object execute(SqlSession sqlSession, Object[] args) {
    Object result;
    switch (command.getType()) {
      case INSERT: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.insert(command.getName(), param));
        break;
      }
      case UPDATE: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.update(command.getName(), param));
        break;
      }
      case DELETE: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.delete(command.getName(), param));
        break;
      }
      case SELECT:
        if (method.returnsVoid() && method.hasResultHandler()) {
          executeWithResultHandler(sqlSession, args);
          result = null;
        } else if (method.returnsMany()) {
          result = executeForMany(sqlSession, args);
        } else if (method.returnsMap()) {
          result = executeForMap(sqlSession, args);
        } else if (method.returnsCursor()) {
          result = executeForCursor(sqlSession, args);
        } else {
          Object param = method.convertArgsToSqlCommandParam(args);
          result = sqlSession.selectOne(command.getName(), param);
          if (method.returnsOptional()
              && (result == null || !method.getReturnType().equals(result.getClass()))) {
            result = Optional.ofNullable(result);
          }
        }
        break;
      case FLUSH:
        result = sqlSession.flushStatements();
        break;
      default:
        throw new BindingException("Unknown execution method for: " + command.getName());
    }
    if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid()) {
      throw new BindingException("Mapper method '" + command.getName()
          + "' attempted to return null from a method with a primitive return type (" + method.getReturnType() + ").");
    }
    return result;
  }

根据sql执行类型执行不同操作。method.convertArgsToSqlCommandParam通过上面的paramNameResolver设置的names和实际参数获取参数名和参数值。且会增加param+参数下标为key,参数值为value到map中。比如names为0->id,参数为[1],则返回值为id->1,param1->1。sqlSession.selectOne执行查询。

DefaultSqlSession.selectOne(String statement, Object parameter)

  public <T> T selectOne(String statement, Object parameter) {
    // Popular vote was to return null on 0 results and throw exception on too many.
    List<T> list = this.selectList(statement, parameter);
    if (list.size() == 1) {
      return list.get(0);
    } else if (list.size() > 1) {
      throw new TooManyResultsException("Expected one result (or null) to be returned by selectOne(), but found: " + list.size());
    } else {
      return null;
    }
  }

selectOne调用selectList执行的。

DefaultSqlSession.selectList(String statement, Object parameter)

public <E> List<E> selectList(String statement, Object parameter) {
  return this.selectList(statement, parameter, RowBounds.DEFAULT);
}

RowBounds是分页用的。

DefaultSqlSession.selectList(String statement, Object parameter, RowBounds rowBounds)

 public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) {
    return selectList(statement, parameter, rowBounds, Executor.NO_RESULT_HANDLER);
  }

DefaultSqlSession.selectList(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler)

private <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler) {
    try {
      MappedStatement ms = configuration.getMappedStatement(statement);
      return executor.query(ms, wrapCollection(parameter), rowBounds, handler);
    } catch (Exception e) {
      throw ExceptionFactory.wrapException("Error querying database.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }
  }

executor执行查询。

CachingExecutor.query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler)

 public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler) throws SQLException {
    BoundSql boundSql = ms.getBoundSql(parameterObject);
    CacheKey key = createCacheKey(ms, parameterObject, rowBounds, boundSql);
    return query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
  }

BoundSql保存了要执行的sql。CacheKey是缓存的key。此处ms.getBoundSql处理动态sql的拼接。在解析mapper xml文件时没有拼接动态sql,封装成了对应的Node,此时才做sql拼接。同时将#{}参数设置为?。

CachingExecutor.query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)

 public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)
  throws SQLException {
    Cache cache = ms.getCache();
    if (cache != null) {
      flushCacheIfRequired(ms);
      if (ms.isUseCache() && resultHandler == null) {
        ensureNoOutParams(ms, boundSql);
        @SuppressWarnings("unchecked")
        List<E> list = (List<E>) tcm.getObject(cache, key);
        if (list == null) {
          list = delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
          tcm.putObject(cache, key, list); // issue #578 and #116
        }
        return list;
      }
    }
    return delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
  }

获取cache,能获取则处理缓存。否则查询数据库。

BaseExecutor.query(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)

  public <E> List<E> query(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException                             
  {
              ErrorContext.instance().resource(ms.getResource()).activity("executing a query").object(ms.getId());
              if (closed) {
                throw new ExecutorException("Executor was closed.");
              }
              if (queryStack == 0 && ms.isFlushCacheRequired()) {
                clearLocalCache();
              }
              List<E> list;
              try {
                queryStack++;
                list = resultHandler == null ? (List<E>) localCache.getObject(key) : null;
                if (list != null) {
                  handleLocallyCachedOutputParameters(ms, key, parameter, boundSql);
                } else {
                  list = queryFromDatabase(ms, parameter, rowBounds, resultHandler, key, boundSql);
                }
              } finally {
                queryStack--;
              }
              if (queryStack == 0) {
                for (DeferredLoad deferredLoad : deferredLoads) {
                  deferredLoad.load();
                }
                // issue #601
                deferredLoads.clear();
                if (configuration.getLocalCacheScope() == LocalCacheScope.STATEMENT) {
                  // issue #482
                  clearLocalCache();
                }
              }
              return list;
            }

localCache是一级缓存。如果能从缓存获取则从缓存获取。否则查询数据库。

BaseExecutor.queryFromDatabase(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)

  private <E> List<E> queryFromDatabase(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws             
  SQLException {
    List<E> list;
    localCache.putObject(key, EXECUTION_PLACEHOLDER);
    try {
      list = doQuery(ms, parameter, rowBounds, resultHandler, boundSql);
    } finally {
      localCache.removeObject(key);
    }
    localCache.putObject(key, list);
    if (ms.getStatementType() == StatementType.CALLABLE) {
      localOutputParameterCache.putObject(key, parameter);
    }
    return list;
  }

doQuery执行实际查询。

SimpleExecutor.doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql)

 public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
    Statement stmt = null;
    try {
      Configuration configuration = ms.getConfiguration();
      StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);
      stmt = prepareStatement(handler, ms.getStatementLog());
      return handler.query(stmt, resultHandler);
    } finally {
      closeStatement(stmt);
    }
  }

获取StatementHandler。prepareStatement通过StatementHandler获取Statement。

SimpleExecutor.prepareStatement(StatementHandler handler, Log statementLog)

  private Statement prepareStatement(StatementHandler handler, Log statementLog) throws SQLException {
    Statement stmt;
    Connection connection = getConnection(statementLog);
    stmt = handler.prepare(connection, transaction.getTimeout());
    handler.parameterize(stmt);
    return stmt;
  }

获取连接。获取Statement。handler.parameterize为Statement设置参数值。

BaseStatementHandler.prepare(Connection connection, Integer transactionTimeout)

  public Statement prepare(Connection connection, Integer transactionTimeout) throws SQLException {
    ErrorContext.instance().sql(boundSql.getSql());
    Statement statement = null;
    try {
      statement = instantiateStatement(connection);
      setStatementTimeout(statement, transactionTimeout);
      setFetchSize(statement);
      return statement;
    } catch (SQLException e) {
      closeStatement(statement);
      throw e;
    } catch (Exception e) {
      closeStatement(statement);
      throw new ExecutorException("Error preparing statement.  Cause: " + e, e);
    }
  }

获取statement并设置FetchSize和Timeout。

DefaultParameterHandler.setParameters(PreparedStatement ps)

public void setParameters(PreparedStatement ps) {
  ErrorContext.instance().activity("setting parameters").object(mappedStatement.getParameterMap().getId());
  List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
  if (parameterMappings != null) {
    for (int i = 0; i < parameterMappings.size(); i++) {
      ParameterMapping parameterMapping = parameterMappings.get(i);
      if (parameterMapping.getMode() != ParameterMode.OUT) {
        Object value;
        String propertyName = parameterMapping.getProperty();
        if (boundSql.hasAdditionalParameter(propertyName)) { // issue #448 ask first for additional params
          value = boundSql.getAdditionalParameter(propertyName);
        } else if (parameterObject == null) {
          value = null;
        } else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
          value = parameterObject;
        } else {
          MetaObject metaObject = configuration.newMetaObject(parameterObject);
          value = metaObject.getValue(propertyName);
        }
        TypeHandler typeHandler = parameterMapping.getTypeHandler();
        JdbcType jdbcType = parameterMapping.getJdbcType();
        if (value == null && jdbcType == null) {
          jdbcType = configuration.getJdbcTypeForNull();
        }
        try {
          typeHandler.setParameter(ps, i + 1, value, jdbcType);
        } catch (TypeException | SQLException e) {
          throw new TypeException("Could not set parameters for mapping: " + parameterMapping + ". Cause: " + e, e);
        }
      }
    }
  }
}

获取TypeHandler为PreparedStatement设置参数值。

BaseTypeHandler.setParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType)

public void setParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
    if (parameter == null) {
      if (jdbcType == null) {
        throw new TypeException("JDBC requires that the JdbcType must be specified for all nullable parameters.");
      }
      try {
        ps.setNull(i, jdbcType.TYPE_CODE);
      } catch (SQLException e) {
        throw new TypeException("Error setting null for parameter #" + i + " with JdbcType " + jdbcType + " . "
              + "Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. "
              + "Cause: " + e, e);
      }
    } else {
      try {
        setNonNullParameter(ps, i, parameter, jdbcType);
      } catch (Exception e) {
        throw new TypeException("Error setting non null for parameter #" + i + " with JdbcType " + jdbcType + " . "
              + "Try setting a different JdbcType for this parameter or a different configuration property. "
              + "Cause: " + e, e);
      }
    }
  }

setNonNullParameter设置非空参数。setNull设置空参数。

UnknownTypeHandler.setNonNullParameter(PreparedStatement ps, int i, Object parameter, JdbcType jdbcType)

 public void setNonNullParameter(PreparedStatement ps, int i, Object parameter, JdbcType jdbcType)
 throws SQLException {
    TypeHandler handler = resolveTypeHandler(parameter, jdbcType);
    handler.setParameter(ps, i, parameter, jdbcType);
  }

根据参数类型和jdbcType解析出对应的TypeHandler。调用handler.setParameter为PreparedStatement设置参数。

IntegerTypeHandler.setNonNullParameter(PreparedStatement ps, int i, Integer parameter, JdbcType jdbcType)

public void setNonNullParameter(PreparedStatement ps, int i, Integer parameter, JdbcType jdbcType)
  throws SQLException {
    ps.setInt(i, parameter);
  }

为PreparedStatement设置参数。

PreparedStatementHandler.query(Statement statement, ResultHandler resultHandler)

 public <E> List<E> query(Statement statement, ResultHandler resultHandler) throws SQLException {
    PreparedStatement ps = (PreparedStatement) statement;
    ps.execute();
    return resultSetHandler.handleResultSets(ps);
  }

执行查询后设置结果。

DefaultResultSetHandler.handleResultSets(Statement stmt)

public List<Object> handleResultSets(Statement stmt) throws SQLException {
    ErrorContext.instance().activity("handling results").object(mappedStatement.getId());

    final List<Object> multipleResults = new ArrayList<>();

    int resultSetCount = 0;
    ResultSetWrapper rsw = getFirstResultSet(stmt);

    List<ResultMap> resultMaps = mappedStatement.getResultMaps();
    int resultMapCount = resultMaps.size();
    validateResultMapsCount(rsw, resultMapCount);
    while (rsw != null && resultMapCount > resultSetCount) {
      ResultMap resultMap = resultMaps.get(resultSetCount);
      handleResultSet(rsw, resultMap, multipleResults, null);
      rsw = getNextResultSet(stmt);
      cleanUpAfterHandlingResultSet();
      resultSetCount++;
    }

    String[] resultSets = mappedStatement.getResultSets();
    if (resultSets != null) {
      while (rsw != null && resultSetCount < resultSets.length) {
        ResultMapping parentMapping = nextResultMaps.get(resultSets[resultSetCount]);
        if (parentMapping != null) {
          String nestedResultMapId = parentMapping.getNestedResultMapId();
          ResultMap resultMap = configuration.getResultMap(nestedResultMapId);
          handleResultSet(rsw, resultMap, null, parentMapping);
        }
        rsw = getNextResultSet(stmt);
        cleanUpAfterHandlingResultSet();
        resultSetCount++;
      }
    }

    return collapseSingleResultList(multipleResults);
  }

1、getFirstResultSet获取ResultSet
2、遍历ResultMap集合,依次调用handleResultSet处理结果集。

DefaultResultSetHandler.getFirstResultSet(Statement stmt)

  private ResultSetWrapper getFirstResultSet(Statement stmt) throws SQLException {
  ResultSet rs = stmt.getResultSet();
  while (rs == null) {
    // move forward to get the first resultset in case the driver
    // doesn't return the resultset as the first result (HSQLDB 2.1)
    if (stmt.getMoreResults()) {
      rs = stmt.getResultSet();
    } else {
      if (stmt.getUpdateCount() == -1) {
        // no more results. Must be no resultset
        break;
      }
    }
  }
  return rs != null ? new ResultSetWrapper(rs, configuration) : null;
}

获取ResultSet并封装成ResultSetWrapper。

ResultSetWrapper(ResultSet rs, Configuration configuration)

 public ResultSetWrapper(ResultSet rs, Configuration configuration) throws SQLException {
    super();
    this.typeHandlerRegistry = configuration.getTypeHandlerRegistry();
    this.resultSet = rs;
    final ResultSetMetaData metaData = rs.getMetaData();
    final int columnCount = metaData.getColumnCount();
    for (int i = 1; i <= columnCount; i++) {
      columnNames.add(configuration.isUseColumnLabel() ? metaData.getColumnLabel(i) : metaData.getColumnName(i));
      jdbcTypes.add(JdbcType.forCode(metaData.getColumnType(i)));
      classNames.add(metaData.getColumnClassName(i));
    }
  }

将resultSet中的列名,列对应的JdbcType,列对应的java类型分别加到columnNames,jdbcTypes,classNames。

DefaultResultSetHandler.handleResultSet(ResultSetWrapper rsw, ResultMap resultMap, List

标签:return,流程,Object,ms,sql,mybatis,null,parameter,method
From: https://www.cnblogs.com/shigongp/p/16929913.html

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