flink消费kafka进行聚合计算的代码实例

可以参考以下代码实例：

import org.apache.flink.api.common.functions.AggregateFunction;
import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;

import java.util.Properties;

public class KafkaFlinkAggregation {

    public static void main(String[] args) throws Exception {

        // set up the execution environment
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // set up the properties for the Kafka consumer
        Properties props = new Properties();
        props.setProperty("bootstrap.servers", "localhost:9092");
        props.setProperty("group.id", "test");

        // create a Kafka consumer
        FlinkKafkaConsumer<String> consumer = new FlinkKafkaConsumer<>("my-topic", new SimpleStringSchema(), props);

        // add the Kafka consumer as a source to the Flink job
        DataStream<String> stream = env.addSource(consumer);

        // perform aggregation on the stream
        DataStream<Integer> aggregatedStream = stream
                .map(Integer::parseInt)
                .keyBy(value -> value % 2)
                .aggregate(new SumAggregator());

        // print the results
        aggregatedStream.print();

        // execute the Flink job
        env.execute("Kafka Flink Aggregation");
    }

    private static class SumAggregator implements AggregateFunction<Integer, Integer, Integer> {

        @Override
        public Integer createAccumulator() {
            return ;
        }

        @Override
        public Integer add(Integer value, Integer accumulator) {
            return value + accumulator;
        }

        @Override
        public Integer getResult(Integer accumulator) {
            return accumulator;
        }

        @Override
        public Integer merge(Integer a, Integer b) {
            return a + b;
        }
    }
}