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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.examples.sql.streaming;
+
+import org.apache.spark.api.java.function.FlatMapFunction;
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Encoders;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.streaming.StreamingQuery;
+
+import java.util.Arrays;
+import java.util.Iterator;
+
+/**
+ * Consumes messages from one or more topics in Kafka and does wordcount.
+ * Usage: JavaStructuredKafkaWordCount <bootstrap-servers> <subscribe-type> <topics>
+ * <bootstrap-servers> The Kafka "bootstrap.servers" configuration. A
+ * comma-separated list of host:port.
+ * <subscribe-type> There are three kinds of type, i.e. 'assign', 'subscribe',
+ * 'subscribePattern'.
+ * |- <assign> Specific TopicPartitions to consume. Json string
+ * | {"topicA":[0,1],"topicB":[2,4]}.
+ * |- <subscribe> The topic list to subscribe. A comma-separated list of
+ * | topics.
+ * |- <subscribePattern> The pattern used to subscribe to topic(s).
+ * | Java regex string.
+ * |- Only one of "assign, "subscribe" or "subscribePattern" options can be
+ * | specified for Kafka source.
+ * <topics> Different value format depends on the value of 'subscribe-type'.
+ *
+ * Example:
+ * `$ bin/run-example \
+ * sql.streaming.JavaStructuredKafkaWordCount host1:port1,host2:port2 \
+ * subscribe topic1,topic2`
+ */
+public final class JavaStructuredKafkaWordCount {
+
+ public static void main(String[] args) throws Exception {
+ if (args.length < 3) {
+ System.err.println("Usage: JavaStructuredKafkaWordCount <bootstrap-servers> " +
+ "<subscribe-type> <topics>");
+ System.exit(1);
+ }
+
+ String bootstrapServers = args[0];
+ String subscribeType = args[1];
+ String topics = args[2];
+
+ SparkSession spark = SparkSession
+ .builder()
+ .appName("JavaStructuredKafkaWordCount")
+ .getOrCreate();
+
+ // Create DataSet representing the stream of input lines from kafka
+ Dataset<String> lines = spark
+ .readStream()
+ .format("kafka")
+ .option("kafka.bootstrap.servers", bootstrapServers)
+ .option(subscribeType, topics)
+ .load()
+ .selectExpr("CAST(value AS STRING)")
+ .as(Encoders.STRING());
+
+ // Generate running word count
+ Dataset<Row> wordCounts = lines.flatMap(new FlatMapFunction<String, String>() {
+ @Override
+ public Iterator<String> call(String x) {
+ return Arrays.asList(x.split(" ")).iterator();
+ }
+ }, Encoders.STRING()).groupBy("value").count();
+
+ // Start running the query that prints the running counts to the console
+ StreamingQuery query = wordCounts.writeStream()
+ .outputMode("complete")
+ .format("console")
+ .start();
+
+ query.awaitTermination();
+ }
+}