4.12 Kafka源码剖析之KafkaApis

当启动KafkaServer的时候，在其startup方法中实例化了KafkaApi，并赋值给KafkaRequestHandlerPool用于执行具体的请求处理逻辑：

KafkaApi 主构造器参数：

各种请求的处理逻辑入口：

使用模式匹配：

case ApiKeys.PRODUCE => handleProduceRequest(request)
case ApiKeys.FETCH => handleFetchRequest(request)
case ApiKeys.LIST_OFFSETS => handleListOffsetRequest(request)
case ApiKeys.METADATA => handleTopicMetadataRequest(request)
case ApiKeys.LEADER_AND_ISR => handleLeaderAndIsrRequest(request)
case ApiKeys.STOP_REPLICA => handleStopReplicaRequest(request)
case ApiKeys.UPDATE_METADATA => handleUpdateMetadataRequest(request)
case ApiKeys.CONTROLLED_SHUTDOWN => handleControlledShutdownRequest(request)
case ApiKeys.OFFSET_COMMIT => handleOffsetCommitRequest(request)
case ApiKeys.OFFSET_FETCH => handleOffsetFetchRequest(request)
case ApiKeys.FIND_COORDINATOR =>handleFindCoordinatorRequest(request)
case ApiKeys.JOIN_GROUP => handleJoinGroupRequest(request)
case ApiKeys.HEARTBEAT => handleHeartbeatRequest(request)
case ApiKeys.LEAVE_GROUP => handleLeaveGroupRequest(request)
case ApiKeys.SYNC_GROUP => handleSyncGroupRequest(request)
case ApiKeys.DESCRIBE_GROUPS => handleDescribeGroupRequest(request)
case ApiKeys.LIST_GROUPS => handleListGroupsRequest(request)
case ApiKeys.SASL_HANDSHAKE => handleSaslHandshakeRequest(request)
case ApiKeys.API_VERSIONS => handleApiVersionsRequest(request)
case ApiKeys.CREATE_TOPICS => handleCreateTopicsRequest(request)
case ApiKeys.DELETE_TOPICS => handleDeleteTopicsRequest(request)
case ApiKeys.DELETE_RECORDS => handleDeleteRecordsRequest(request)
case ApiKeys.INIT_PRODUCER_ID =>handleInitProducerIdRequest(request)
case ApiKeys.OFFSET_FOR_LEADER_EPOCH =>handleOffsetForLeaderEpochRequest(request)
case ApiKeys.ADD_PARTITIONS_TO_TXN =>handleAddPartitionToTxnRequest(request)
case ApiKeys.ADD_OFFSETS_TO_TXN =>handleAddOffsetsToTxnRequest(request)
case ApiKeys.END_TXN => handleEndTxnRequest(request)
case ApiKeys.WRITE_TXN_MARKERS =>handleWriteTxnMarkersRequest(request)
case ApiKeys.TXN_OFFSET_COMMIT =>handleTxnOffsetCommitRequest(request)
case ApiKeys.DESCRIBE_ACLS => handleDescribeAcls(request)
case ApiKeys.CREATE_ACLS => handleCreateAcls(request)
case ApiKeys.DELETE_ACLS => handleDeleteAcls(request)
case ApiKeys.ALTER_CONFIGS => handleAlterConfigsRequest(request)
case ApiKeys.DESCRIBE_CONFIGS =>handleDescribeConfigsRequest(request)
case ApiKeys.ALTER_REPLICA_LOG_DIRS =>handleAlterReplicaLogDirsRequest(request)
case ApiKeys.DESCRIBE_LOG_DIRS =>handleDescribeLogDirsRequest(request)
case ApiKeys.SASL_AUTHENTICATE =>handleSaslAuthenticateRequest(request)
case ApiKeys.CREATE_PARTITIONS =>handleCreatePartitionsRequest(request)