使用Spark Streaming将处理后的数据写入Cassandra的Java代码示例

以下是一个使用Spark Streaming将处理后的数据写入Cassandra的Java代码示例，你可以参考：

import java.util.HashMap;
import java.util.Map;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.streaming.Duration;
import org.apache.spark.streaming.api.java.JavaDStream;
import org.apache.spark.streaming.api.java.JavaPairDStream;
import org.apache.spark.streaming.api.java.JavaStreamingContext;

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.Session;
import com.datastax.spark.connector.japi.CassandraJavaUtil;

public class SparkCassandraExample {
    
    
    public static void main(String[] args) {
    
    
        SparkConf conf = new SparkConf().setAppName("SparkCassandraExample").setMaster("local[*]");
        JavaStreamingContext jssc = new JavaStreamingContext(conf, new Duration(1000));

        Map<String, String> cassandraConfig = new HashMap<>();
        cassandraConfig.put("keyspace", "test");
        cassandraConfig.put("table", "wordcount");

        JavaDStream<String> lines = jssc.socketTextStream("localhost", 9999);
        JavaPairDStream<String, Integer> wordCounts = lines.flatMap(x -> Arrays.asList(x.split(" ")).iterator())
                .mapToPair(x -> new Tuple2<>(x, 1)).reduceByKey((x, y) -> x + y);

        wordCounts.foreachRDD(new Function<JavaPairRDD<String, Integer>, Void>() {
    
    
            @Override
            public Void call(JavaPairRDD<String, Integer> rdd) throws Exception {
    
    
                CassandraJavaUtil.javaFunctions(rdd).writerBuilder("test", "wordcount",
                        CassandraJavaUtil.mapToRow(String.class, Integer.class)).saveToCassandra();
                return null;
            }
        });

        jssc.start();
        jssc.awaitTermination();
    }
}

这段代码使用了 Spark Streaming 从一个 socket 端口读取数据，然后将数据转换为单词计数，并将结果写入 Cassandra 数据库。

(1) Writing Spark Structure Streaming data into Cassandra. https://stackoverflow.com/questions/50037285/writing-spark-structure-streaming-data-into-cassandra.
(2) Accessing Cassandra from Spark in Java | Datastax. https://www.datastax.com/blog/accessing-cassandra-spark-java.
(3) Spark Structured streaming with cassandra - Stack Overflow. https://stackoverflow.com/questions/61469208/spark-structured-streaming-with-cassandra.