Spark Streaming是构建在Spark Core的RDD基础之上的，与此同时Spark Streaming引入了一个新的概念：DStream（Discretized Stream，离散化数据流)，表示连续不断的数据流。DStream抽象是Spark Streaming的流处理模型，在内部实现上，Spark Streaming会对输入数据按照时间间隔（如1秒）分段，每一段数据转换为Spark中的RDD，这些分段就是Dstream，并且对DStream的操作都最终转变为对相应的RDD的操作。
Spark SQL 是 Spark 用于结构化数据(structured data)处理的 Spark 模块。Spark SQL 的前身是Shark，Shark是基于 Hive 所开发的工具，它修改了下图所示的右下角的内存管理、物理计划、执行三个模块，并使之能运行在 Spark 引擎上。
1.png
（1）pom依赖：
<dependencies>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_${scala.version}</artifactId>
<version>${spark.version}</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming_${scala.version}</artifactId>
<version>${spark.version}</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-sql_${scala.version}</artifactId>
<version>${spark.version}</version>
</dependency>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>2.11.11</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming-kafka-0-10_2.11</artifactId>
<version>2.3.1</version>
</dependency>
<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka-clients</artifactId>
<version>2.3.1</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.66</version>
</dependency>
</dependencies>
（2）定义消息对象
package com.pojo;
import java.io.Serializable;
import java.util.Date;
/**
* Created by lj on 2022-07-13.
*/
public class WaterSensor implements Serializable {
public String id;
public long ts;
public int vc;
public WaterSensor(){
}
public WaterSensor(String id,long ts,int vc){
this.id = id;
this.ts = ts;
this.vc = vc;
}
public int getVc() {
return vc;
}
public void setVc(int vc) {
this.vc = vc;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public long getTs() {
return ts;
}
public void setTs(long ts) {
this.ts = ts;
}
}
（3）构建数据生产者
package com.producers;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Random;
/**
* Created by lj on 2022-07-12.
*/
public class Socket_Producer {
public static void main(String[] args) throws IOException {
try {
ServerSocket ss = new ServerSocket(9999);
System.out.println("启动 server ....");
Socket s = ss.accept();
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
String response = "java,1,2";
//每 2s 发送一次消息
int i = 0;
Random r=new Random(); //不传入种子
String[] lang = {"flink","spark","hadoop","hive","hbase","impala","presto","superset","nbi"};
while(true){
response= lang[r.nextInt(lang.length)]+ i + "," + i + "," + i+"\n";
System.out.println(response);
try{
bw.write(response);
bw.flush();
i++;
}catch (Exception ex){
System.out.println(ex.getMessage());
}
Thread.sleep(1000 * 30);
}
} catch (IOException | InterruptedException e) {
e.printStackTrace();
}
}
}
（4）通过sparkstreaming接入socket数据源，sparksql计算结果打印输出：
package com.examples;
import com.pojo.WaterSensor;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.api.java.function.Function2;
import org.apache.spark.api.java.function.VoidFunction2;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.SparkSession;
import org.apache.spark.streaming.Durations;
import org.apache.spark.streaming.Time;
import org.apache.spark.streaming.api.java.JavaReceiverInputDStream;
import org.apache.spark.streaming.api.java.JavaStreamingContext;
/**
* Created by lj on 2022-07-16.
*/
public class SparkSql_Socket1 {
private static String appName = "spark.streaming.demo";
private static String master = "local[*]";
private static String host = "localhost";
private static int port = 9999;
public static void main(String[] args) {
//初始化sparkConf
SparkConf sparkConf = new SparkConf().setMaster(master).setAppName(appName);
//获得JavaStreamingContext
JavaStreamingContext ssc = new JavaStreamingContext(sparkConf, Durations.minutes(1));
//从socket源获取数据
JavaReceiverInputDStream<String> lines = ssc.socketTextStream(host, port);
//将 DStream 转换成 DataFrame 并且运行sql查询
lines.foreachRDD(new VoidFunction2<JavaRDD<String>, Time>() {
@Override
public void call(JavaRDD<String> rdd, Time time) {
SparkSession spark = JavaSparkSessionSingleton.getInstance(rdd.context().getConf());
//通过反射将RDD转换为DataFrame
JavaRDD<WaterSensor> rowRDD = rdd.map(new Function<String, WaterSensor>() {
@Override
public WaterSensor call(String line) {
String[] cols = line.split(",");
WaterSensor waterSensor = new WaterSensor(cols[0],Long.parseLong(cols[1]),Integer.parseInt(cols[2]));
return waterSensor;
}
});
Dataset<Row> dataFrame = spark.createDataFrame(rowRDD, WaterSensor.class);
// 创建临时表
dataFrame.createOrReplaceTempView("log");
Dataset<Row> result = spark.sql("select * from log");
System.out.println("========= " + time + "=========");
//输出前20条数据
result.show();
}
});
//开始作业
ssc.start();
try {
ssc.awaitTermination();
} catch (Exception e) {
e.printStackTrace();
} finally {
ssc.close();
}
}
}
（5）效果演示：
2.png
代码中定义的是1分钟的批处理间隔，所以每1分钟会触发一次计算：
3.png
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