• java kafka客户端何时设置的kafka消费者默认值

    kafka为什么有些属性没有配置却能正常工作，那是因为kafka-clients对有些消费者设置了默认值，具体看下ConsumerConfig类的静态模块，具体如下所示：

    1. kafka为什么有些属性没有配置却能正常工作，那是因为kafka-clients对有些消费者设置了默认值，具体看下ConsumerConfig类的静态模块，具体如下所示：
    2.  
    3. static {
    4.     CONFIG = new ConfigDef().define(BOOTSTRAP_SERVERS_CONFIG,
    5.                                     Type.LIST,
    6.                                     Collections.emptyList(),
    7.                                     new ConfigDef.NonNullValidator(),
    8.                                     Importance.HIGH,
    9.                                     CommonClientConfigs.BOOTSTRAP_SERVERS_DOC)
    10.                             .define(CLIENT_DNS_LOOKUP_CONFIG,
    11.                                     Type.STRING,
    12.                                     ClientDnsLookup.USE_ALL_DNS_IPS.toString(),
    13.                                     in(ClientDnsLookup.DEFAULT.toString(),
    14.                                        ClientDnsLookup.USE_ALL_DNS_IPS.toString(),
    15.                                        ClientDnsLookup.RESOLVE_CANONICAL_BOOTSTRAP_SERVERS_ONLY.toString()),
    16.                                     Importance.MEDIUM,
    17.                                     CommonClientConfigs.CLIENT_DNS_LOOKUP_DOC)
    18.                             .define(GROUP_ID_CONFIG, Type.STRING, null, Importance.HIGH, GROUP_ID_DOC)
    19.                             .define(GROUP_INSTANCE_ID_CONFIG,
    20.                                     Type.STRING,
    21.                                     null,
    22.                                     Importance.MEDIUM,
    23.                                     GROUP_INSTANCE_ID_DOC)
    24.                             .define(SESSION_TIMEOUT_MS_CONFIG,
    25.                                     Type.INT,
    26.                                     10000,
    27.                                     Importance.HIGH,
    28.                                     SESSION_TIMEOUT_MS_DOC)
    29.                             .define(HEARTBEAT_INTERVAL_MS_CONFIG,
    30.                                     Type.INT,
    31.                                     3000,
    32.                                     Importance.HIGH,
    33.                                     HEARTBEAT_INTERVAL_MS_DOC)
    34.                             .define(PARTITION_ASSIGNMENT_STRATEGY_CONFIG,
    35.                                     Type.LIST,
    36.                                     Collections.singletonList(RangeAssignor.class),
    37.                                     new ConfigDef.NonNullValidator(),
    38.                                     Importance.MEDIUM,
    39.                                     PARTITION_ASSIGNMENT_STRATEGY_DOC)
    40.                             .define(METADATA_MAX_AGE_CONFIG,
    41.                                     Type.LONG,
    42.                                     5 * 60 * 1000,
    43.                                     atLeast(0),
    44.                                     Importance.LOW,
    45.                                     CommonClientConfigs.METADATA_MAX_AGE_DOC)
    46.                             .define(ENABLE_AUTO_COMMIT_CONFIG,
    47.                                     Type.BOOLEAN,
    48.                                     true,
    49.                                     Importance.MEDIUM,
    50.                                     ENABLE_AUTO_COMMIT_DOC)
    51.                             .define(AUTO_COMMIT_INTERVAL_MS_CONFIG,
    52.                                     Type.INT,
    53.                                     5000,
    54.                                     atLeast(0),
    55.                                     Importance.LOW,
    56.                                     AUTO_COMMIT_INTERVAL_MS_DOC)
    57.                             .define(CLIENT_ID_CONFIG,
    58.                                     Type.STRING,
    59.                                     "",
    60.                                     Importance.LOW,
    61.                                     CommonClientConfigs.CLIENT_ID_DOC)
    62.                             .define(CLIENT_RACK_CONFIG,
    63.                                     Type.STRING,
    64.                                     "",
    65.                                     Importance.LOW,
    66.                                     CommonClientConfigs.CLIENT_RACK_DOC)
    67.                             .define(MAX_PARTITION_FETCH_BYTES_CONFIG,
    68.                                     Type.INT,
    69.                                     DEFAULT_MAX_PARTITION_FETCH_BYTES,
    70.                                     atLeast(0),
    71.                                     Importance.HIGH,
    72.                                     MAX_PARTITION_FETCH_BYTES_DOC)
    73.                             .define(SEND_BUFFER_CONFIG,
    74.                                     Type.INT,
    75.                                     128 * 1024,
    76.                                     atLeast(CommonClientConfigs.SEND_BUFFER_LOWER_BOUND),
    77.                                     Importance.MEDIUM,
    78.                                     CommonClientConfigs.SEND_BUFFER_DOC)
    79.                             .define(RECEIVE_BUFFER_CONFIG,
    80.                                     Type.INT,
    81.                                     64 * 1024,
    82.                                     atLeast(CommonClientConfigs.RECEIVE_BUFFER_LOWER_BOUND),
    83.                                     Importance.MEDIUM,
    84.                                     CommonClientConfigs.RECEIVE_BUFFER_DOC)
    85.                             .define(FETCH_MIN_BYTES_CONFIG,
    86.                                     Type.INT,
    87.                                     1,
    88.                                     atLeast(0),
    89.                                     Importance.HIGH,
    90.                                     FETCH_MIN_BYTES_DOC)
    91.                             .define(FETCH_MAX_BYTES_CONFIG,
    92.                                     Type.INT,
    93.                                     DEFAULT_FETCH_MAX_BYTES,
    94.                                     atLeast(0),
    95.                                     Importance.MEDIUM,
    96.                                     FETCH_MAX_BYTES_DOC)
    97.                             .define(FETCH_MAX_WAIT_MS_CONFIG,
    98.                                     Type.INT,
    99.                                     500,
    100.                                     atLeast(0),
    101.                                     Importance.LOW,
    102.                                     FETCH_MAX_WAIT_MS_DOC)
    103.                             .define(RECONNECT_BACKOFF_MS_CONFIG,
    104.                                     Type.LONG,
    105.                                     50L,
    106.                                     atLeast(0L),
    107.                                     Importance.LOW,
    108.                                     CommonClientConfigs.RECONNECT_BACKOFF_MS_DOC)
    109.                             .define(RECONNECT_BACKOFF_MAX_MS_CONFIG,
    110.                                     Type.LONG,
    111.                                     1000L,
    112.                                     atLeast(0L),
    113.                                     Importance.LOW,
    114.                                     CommonClientConfigs.RECONNECT_BACKOFF_MAX_MS_DOC)
    115.                             .define(RETRY_BACKOFF_MS_CONFIG,
    116.                                     Type.LONG,
    117.                                     100L,
    118.                                     atLeast(0L),
    119.                                     Importance.LOW,
    120.                                     CommonClientConfigs.RETRY_BACKOFF_MS_DOC)
    121.                       
    122.                             .define(AUTO_OFFSET_RESET_CONFIG,
    123.                                     Type.STRING,
    124.                                     "latest",  //
    125.                                     in("latest", "earliest", "none"),
    126.                                     Importance.MEDIUM,
    127.                                     AUTO_OFFSET_RESET_DOC)
    128.                             .define(CHECK_CRCS_CONFIG,
    129.                                     Type.BOOLEAN,
    130.                                     true,
    131.                                     Importance.LOW,
    132.                                     CHECK_CRCS_DOC)
    133.                             .define(METRICS_SAMPLE_WINDOW_MS_CONFIG,
    134.                                     Type.LONG,
    135.                                     30000,
    136.                                     atLeast(0),
    137.                                     Importance.LOW,
    138.                                     CommonClientConfigs.METRICS_SAMPLE_WINDOW_MS_DOC)
    139.                             .define(METRICS_NUM_SAMPLES_CONFIG,
    140.                                     Type.INT,
    141.                                     2,
    142.                                     atLeast(1),
    143.                                     Importance.LOW,
    144.                                     CommonClientConfigs.METRICS_NUM_SAMPLES_DOC)
    145.                             .define(METRICS_RECORDING_LEVEL_CONFIG,
    146.                                     Type.STRING,
    147.                                     Sensor.RecordingLevel.INFO.toString(),
    148.                                     in(Sensor.RecordingLevel.INFO.toString(), Sensor.RecordingLevel.DEBUG.toString(), Sensor.RecordingLevel.TRACE.toString()),
    149.                                     Importance.LOW,
    150.                                     CommonClientConfigs.METRICS_RECORDING_LEVEL_DOC)
    151.                             .define(METRIC_REPORTER_CLASSES_CONFIG,
    152.                                     Type.LIST,
    153.                                     Collections.emptyList(),
    154.                                     new ConfigDef.NonNullValidator(),
    155.                                     Importance.LOW,
    156.                                     CommonClientConfigs.METRIC_REPORTER_CLASSES_DOC)
    157.                             .define(KEY_DESERIALIZER_CLASS_CONFIG,
    158.                                     Type.CLASS,
    159.                                     Importance.HIGH,
    160.                                     KEY_DESERIALIZER_CLASS_DOC)
    161.                             .define(VALUE_DESERIALIZER_CLASS_CONFIG,
    162.                                     Type.CLASS,
    163.                                     Importance.HIGH,
    164.                                     VALUE_DESERIALIZER_CLASS_DOC)
    165.                             .define(REQUEST_TIMEOUT_MS_CONFIG,
    166.                                     Type.INT,
    167.                                     30000,
    168.                                     atLeast(0),
    169.                                     Importance.MEDIUM,
    170.                                     REQUEST_TIMEOUT_MS_DOC)
    171.                             .define(DEFAULT_API_TIMEOUT_MS_CONFIG,
    172.                                     Type.INT,
    173.                                     60 * 1000,
    174.                                     atLeast(0),
    175.                                     Importance.MEDIUM,
    176.                                     CommonClientConfigs.DEFAULT_API_TIMEOUT_MS_DOC)
    177.                             .define(SOCKET_CONNECTION_SETUP_TIMEOUT_MS_CONFIG,
    178.                                     Type.LONG,
    179.                                     CommonClientConfigs.DEFAULT_SOCKET_CONNECTION_SETUP_TIMEOUT_MS,
    180.                                     Importance.MEDIUM,
    181.                                     CommonClientConfigs.SOCKET_CONNECTION_SETUP_TIMEOUT_MS_DOC)
    182.                             .define(SOCKET_CONNECTION_SETUP_TIMEOUT_MAX_MS_CONFIG,
    183.                                     Type.LONG,
    184.                                     CommonClientConfigs.DEFAULT_SOCKET_CONNECTION_SETUP_TIMEOUT_MAX_MS,
    185.                                     Importance.MEDIUM,
    186.                                     CommonClientConfigs.SOCKET_CONNECTION_SETUP_TIMEOUT_MAX_MS_DOC)
    187.                             /* default is set to be a bit lower than the server default (10 min), to avoid both client and server closing connection at same time */
    188.                             .define(CONNECTIONS_MAX_IDLE_MS_CONFIG,
    189.                                     Type.LONG,
    190.                                     9 * 60 * 1000,
    191.                                     Importance.MEDIUM,
    192.                                     CommonClientConfigs.CONNECTIONS_MAX_IDLE_MS_DOC)
    193.                             .define(INTERCEPTOR_CLASSES_CONFIG,
    194.                                     Type.LIST,
    195.                                     Collections.emptyList(),
    196.                                     new ConfigDef.NonNullValidator(),
    197.                                     Importance.LOW,
    198.                                     INTERCEPTOR_CLASSES_DOC)
    199.                             .define(MAX_POLL_RECORDS_CONFIG,
    200.                                     Type.INT,
    201.                                     500,
    202.                                     atLeast(1),
    203.                                     Importance.MEDIUM,
    204.                                     MAX_POLL_RECORDS_DOC)
    205.                             .define(MAX_POLL_INTERVAL_MS_CONFIG,
    206.                                     Type.INT,
    207.                                     300000,
    208.                                     atLeast(1),
    209.                                     Importance.MEDIUM,
    210.                                     MAX_POLL_INTERVAL_MS_DOC)
    211.                             .define(EXCLUDE_INTERNAL_TOPICS_CONFIG,
    212.                                     Type.BOOLEAN,
    213.                                     DEFAULT_EXCLUDE_INTERNAL_TOPICS,
    214.                                     Importance.MEDIUM,
    215.                                     EXCLUDE_INTERNAL_TOPICS_DOC)
    216.                             .defineInternal(LEAVE_GROUP_ON_CLOSE_CONFIG,
    217.                                     Type.BOOLEAN,
    218.                                     true,
    219.                                     Importance.LOW)
    220.                             .defineInternal(THROW_ON_FETCH_STABLE_OFFSET_UNSUPPORTED,
    221.                                     Type.BOOLEAN,
    222.                                     false,
    223.                                     Importance.LOW)
    224.                             .define(ISOLATION_LEVEL_CONFIG,
    225.                                     Type.STRING,
    226.                                     DEFAULT_ISOLATION_LEVEL,
    227.                                     in(IsolationLevel.READ_COMMITTED.toString().toLowerCase(Locale.ROOT), IsolationLevel.READ_UNCOMMITTED.toString().toLowerCase(Locale.ROOT)),
    228.                                     Importance.MEDIUM,
    229.                                     ISOLATION_LEVEL_DOC)
    230.                             .define(ALLOW_AUTO_CREATE_TOPICS_CONFIG,
    231.                                     Type.BOOLEAN,
    232.                                     DEFAULT_ALLOW_AUTO_CREATE_TOPICS,
    233.                                     Importance.MEDIUM,
    234.                                     ALLOW_AUTO_CREATE_TOPICS_DOC)
    235.                             // security support
    236.                             .define(SECURITY_PROVIDERS_CONFIG,
    237.                                     Type.STRING,
    238.                                     null,
    239.                                     Importance.LOW,
    240.                                     SECURITY_PROVIDERS_DOC)
    241.                             .define(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG,
    242.                                     Type.STRING,
    243.                                     CommonClientConfigs.DEFAULT_SECURITY_PROTOCOL,
    244.                                     Importance.MEDIUM,
    245.                                     CommonClientConfigs.SECURITY_PROTOCOL_DOC)
    246.                             .withClientSslSupport()
    247.                             .withClientSaslSupport();
    248. }

    像auto.offset.reset这个配置默认值为latest一样，再看下ConsumerConfig的几个构造方法

    1.     public ConsumerConfig(Properties props) {
    2.         super(CONFIG, props);
    3.     }
    4.  
    5.     public ConsumerConfig(Map props) {
    6.         super(CONFIG, props);
    7.     }

    是的，所有的ConsumerConfig构造方法都将上面的默认配置CONFIG传入了构造方法，将下来的处理就是如果显式配置了对应的配置项就使用显式配置数据，没有则使用CONFIG里面的默认配置。

    PS：

    上面的默认配置除了有一些配置的默认配置，一些枚举属性还有其可选值，比如

    auto.offset.reset的可选项

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  • 原文地址：https://blog.csdn.net/john1337/article/details/136715491