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

心已赠人 2023-09-27 20:30 5阅读 0赞

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.