Question

我有以下

//Config setup
Properties props = //setup

List<String> topicList = Arrays.asList({"A", "B", "C"});

StreamBuilder builder = new StreamBuilder();
KStream<String, String> source = builder.stream(topicList);

source
.map((k,v) -> {

  //How can i get the topic of the record here

})
.to((k,v,r) -> {//busy code for topic routing}
);

new KafkaStream(builder.build(), properties).start();

Answer 1

您可以使用ProcessorContext.topic()获得所需的主题名称。要访问ProcessorContext，请使用KStream.process（）为它提供适当的Processor实现。

还可以使用KStream.transform（）：

KStream<InputKeyType, InputValueType> stream2 = stream.transform(new TransformerSupplier<InputKeyType, InputValueType, KeyValue<OutputKeyType, OutputValueType>>() {
            @Override
            public Transformer<InputKeyType, InputValueType, KeyValue<OutputKeyType, OutputValueType>> get() {
                return new Transformer<InputKeyType, InputValueType, KeyValue<OutputKeyType, OutputValueType>>() {
                    private ProcessorContext context;

                    @Override
                    public void init(ProcessorContext context) {
                        this.context = context;
                    }

                    @Override
                    public KeyValue<OutputKeyType, OutputValueType> transform(InputKeyType key, InputValueType value) {

                        this.context.topic() // topic name you need
                        // logic here
                        return new KeyValue<>(OutputKeyType key, OutputValueType value);

                    }

                    @Override
                    public void close() {

                    }
                };
            }
        });

KStreams：如何获得记录的（原始）主题？

1 个答案: