Kafka本地状态存储保存在哪里？

Kafka的本地状态存储默认保存在Kafka Broker所在服务器的磁盘上。可以在创建Topology时通过.withStateStoreDirectory()方法指定存储路径。

代码示例：

Properties props = new Properties();
props.put(StreamsConfig.APPLICATION_ID_CONFIG, "my-stream-processing-app");
props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
props.put(StreamsConfig.STATE_DIR_CONFIG, "/tmp/kafka-streams");
StreamsConfig config = new StreamsConfig(props);

Topology builder = new Topology();
builder.addSource("source", "my-topic")
     .addProcessor("processor", MyProcessor::new, "source")
     .addStateStore(Stores.create("my-store").withStringKeys().withIntegerValues().inMemory().build(), "processor")
     .addSink("sink", "output-topic", "processor");

KafkaStreams streams = new KafkaStreams(builder, config);
streams.start();