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ConsumerRecord 是 Apache Kafka 消费者从主题中读取消息时的核心数据结构，每条消息都会被封装为一个 ConsumerRecord 对象。它包含了消息的元数据（如来源、位置）和实际内容，是消费者处理消息的基础单元。以下是其核心要点：

ConsumerRecord 的结构与字段

每个 ConsumerRecord 包含以下关键信息：

topic：消息所属的 Kafka 主题名称（字符串）

partition：消息所在分区的编号（整数）

offset：消息在分区中的唯一位置标识（长整数），用于追踪消费进度

key：消息的键（泛型），通常用于分区路由或业务标识（如订单ID

value：消息的值（泛型），即实际传输的数据（如 JSON 字符串、二进制数据等）

timestamp：消息的时间戳（长整数），表示消息生成或追加到分区的时间

headers：消息头（键值对集合），用于传递业务元数据（如消息类型、版本号）

checksum：校验和（长整数，已逐步弃用），用于验证消息完整性

在代码中的使用示例

在 Java 或 Spring Kafka 中，ConsumerRecord 通常通过消费者监听器（如 @KafkaListener）接收并处理：

@KafkaListener(topics = "orders")
public void handleOrder(ConsumerRecord<String, Order> record) {String key = record.key();         // 获取消息键（如订单ID）Order value = record.value();     // 获取消息值（如订单对象）String topic = record.topic();     // 获取主题名称long offset = record.offset();     // 获取消息偏移量// 处理业务逻辑...
}

源码

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//package org.apache.kafka.clients.consumer;import java.util.Optional;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.header.internals.RecordHeaders;
import org.apache.kafka.common.record.DefaultRecord;
import org.apache.kafka.common.record.TimestampType;public class ConsumerRecord<K, V> {public static final long NO_TIMESTAMP = -1L;public static final int NULL_SIZE = -1;public static final int NULL_CHECKSUM = -1;private final String topic;private final int partition;private final long offset;private final long timestamp;private final TimestampType timestampType;private final int serializedKeySize;private final int serializedValueSize;private final Headers headers;private final K key;private final V value;private final Optional<Integer> leaderEpoch;private volatile Long checksum;public ConsumerRecord(String topic, int partition, long offset, K key, V value) {this(topic, partition, offset, -1L, TimestampType.NO_TIMESTAMP_TYPE, -1L, -1, -1, key, value);}public ConsumerRecord(String topic, int partition, long offset, long timestamp, TimestampType timestampType, long checksum, int serializedKeySize, int serializedValueSize, K key, V value) {this(topic, partition, offset, timestamp, timestampType, checksum, serializedKeySize, serializedValueSize, key, value, new RecordHeaders());}public ConsumerRecord(String topic, int partition, long offset, long timestamp, TimestampType timestampType, Long checksum, int serializedKeySize, int serializedValueSize, K key, V value, Headers headers) {this(topic, partition, offset, timestamp, timestampType, checksum, serializedKeySize, serializedValueSize, key, value, headers, Optional.empty());}public ConsumerRecord(String topic, int partition, long offset, long timestamp, TimestampType timestampType, Long checksum, int serializedKeySize, int serializedValueSize, K key, V value, Headers headers, Optional<Integer> leaderEpoch) {if (topic == null) {throw new IllegalArgumentException("Topic cannot be null");} else if (headers == null) {throw new IllegalArgumentException("Headers cannot be null");} else {this.topic = topic;this.partition = partition;this.offset = offset;this.timestamp = timestamp;this.timestampType = timestampType;this.checksum = checksum;this.serializedKeySize = serializedKeySize;this.serializedValueSize = serializedValueSize;this.key = key;this.value = value;this.headers = headers;this.leaderEpoch = leaderEpoch;}}public String topic() {return this.topic;}public int partition() {return this.partition;}public Headers headers() {return this.headers;}public K key() {return this.key;}public V value() {return this.value;}public long offset() {return this.offset;}public long timestamp() {return this.timestamp;}public TimestampType timestampType() {return this.timestampType;}/** @deprecated */@Deprecatedpublic long checksum() {if (this.checksum == null) {this.checksum = DefaultRecord.computePartialChecksum(this.timestamp, this.serializedKeySize, this.serializedValueSize);}return this.checksum;}public int serializedKeySize() {return this.serializedKeySize;}public int serializedValueSize() {return this.serializedValueSize;}public Optional<Integer> leaderEpoch() {return this.leaderEpoch;}public String toString() {return "ConsumerRecord(topic = " + this.topic + ", partition = " + this.partition + ", leaderEpoch = " + this.leaderEpoch.orElse((Object)null) + ", offset = " + this.offset + ", " + this.timestampType + " = " + this.timestamp + ", serialized key size = " + this.serializedKeySize + ", serialized value size = " + this.serializedValueSize + ", headers = " + this.headers + ", key = " + this.key + ", value = " + this.value + ")";}
}