# Flink Join样例程序（Scala）
本章节适用于MRS 3.3.0及以后版本。
#### 功能介绍
在Flink应用中，调用flink-connector-kafka模块的接口，生产并消费数据。
#### 代码样例
用户在开发前需要使用对接安全模式的Kafka，则需要引入FusionInsight的kafka-clients-\*.jar，该jar包可在Kafka客户端目录下获取。
下面列出producer和consumer，以及Flink Stream SQL Join使用主要逻辑代码作为演示。
完整代码参见com.huawei.bigdata.flink.examples.WriteIntoKafka和com.huawei.bigdata.flink.examples.SqlJoinWithSocket
1. 每秒钟往Kafka中生产一条用户信息，用户信息由姓名、年龄、性别组成。
   ```
   //producer代码
    
   object WriteIntoKafka {
      def main(args: Array[String]): Unit = {
        System.out.println("use command as: ")
        System.out.println("./bin/flink run --class com.huawei.bigdata.flink.examples.WriteIntoKafka" + " /opt/test.jar --topic topic-test -bootstrap.servers xxx.xxx.xxx.xxx:21005")
        System.out.println("./bin/flink run --class com.huawei.bigdata.flink.examples.WriteIntoKafka /opt/test.jar --topic" + " topic-test -bootstrap.servers xxx.xxx.xxx.xxx:21007 --security.protocol SASL_PLAINTEXT" + " --sasl.kerberos.service.name kafka")
        System.out.println("******************************************************************************************")
        System.out.println("<topic> is the kafka topic name")
        System.out.println("<bootstrap.servers> is the ip:port list of brokers")
        System.out.println("******************************************************************************************")
        val env = StreamExecutionEnvironment.getExecutionEnvironment
   env.setParallelism(1)
        val paraTool = ParameterTool.fromArgs(args)
        val messageStream = env.addSource(new WriteIntoKafka.SimpleStringGenerator)
        val producer = new FlinkKafkaProducer[String](paraTool.get("topic"), new SimpleStringSchema, paraTool.getProperties)
        producer.setWriteTimestampToKafka(true)
        messageStream.addSink(producer)
        env.execute
      }
      /**
       * String source类
       *
       */
      object SimpleStringGenerator {
        private[examples] val NAME = Array("Carry", "Alen", "Mike", "Ian", "John", "Kobe", "James")
        private[examples] val SEX = Array("MALE", "FEMALE")
        private[examples] val COUNT = NAME.length
      }
      class SimpleStringGenerator extends SourceFunction[String] {
        private[examples] var running = true
        private[examples] val rand = new Random(47)
        @throws[Exception]
        override def run(ctx: SourceFunction.SourceContext[String]): Unit = {
          while (running) {
            val i = rand.nextInt(SimpleStringGenerator.COUNT)
            val age = rand.nextInt(70)
            val sexy = SimpleStringGenerator.SEX(rand.nextInt(2))
            ctx.collect(SimpleStringGenerator.NAME(i) + "," + age + "," + sexy)
            Thread.sleep(1000)
          }
        }
        override def cancel(): Unit = {
          running = false
        }
      }
    }
   ```
   
2. 生成Table1和Table2，并使用Join对Table1和Table2进行联合查询，打印输出结果。
   ```
   object SqlJoinWithSocket {
      def main(args: Array[String]): Unit = {
        var hostname: String = null
        var port = 0
        System.out.println("use command as: ")
        System.out.println("flink run --class com.huawei.bigdata.flink.examples.SqlJoinWithSocket /opt/test.jar --topic" + " topic-test -bootstrap.servers xxxx.xxx.xxx.xxx:21005 --hostname xxx.xxx.xxx.xxx --port xxx")
        System.out.println("flink run --class com.huawei.bigdata.flink.examples.SqlJoinWithSocket /opt/test.jar --topic" + " topic-test -bootstrap.servers xxxx.xxx.xxx.xxx:21007 --security.protocol SASL_PLAINTEXT" + " --sasl.kerberos.service.name kafka--hostname xxx.xxx.xxx.xxx --port xxx")
        System.out.println("******************************************************************************************")
        System.out.println("<topic> is the kafka topic name")
        System.out.println("<bootstrap.servers> is the ip:port list of brokers")
        System.out.println("******************************************************************************************")
        try {
          val params = ParameterTool.fromArgs(args)
          hostname = if (params.has("hostname")) params.get("hostname")
          else "localhost"
          port = params.getInt("port")
        } catch {
          case e: Exception =>
            System.err.println("No port specified. Please run 'FlinkStreamSqlJoinExample " + "--hostname <hostname> --port <port>', where hostname (localhost by default) " + "and port is the address of the text server")
            System.err.println("To start a simple text server, run 'netcat -l -p <port>' and " + "type the input text into the command line")
            return
        }
        val fsSettings = EnvironmentSettings.newInstance.inStreamingMode.build
        val env = StreamExecutionEnvironment.getExecutionEnvironment
   val tableEnv = StreamTableEnvironment.create(env, fsSettings)
        env.getConfig.setAutoWatermarkInterval(200)
        env.setParallelism(1)
        val paraTool = ParameterTool.fromArgs(args)
        val kafkaStream = env.addSource(new FlinkKafkaConsumer[String](paraTool.get("topic"), new SimpleStringSchema, paraTool.getProperties)).map(new MapFunction[String, Tuple3[String, String, String]]() {
          @throws[Exception]
          override def map(str: String): Tuple3[String, String, String] = {
            val word = str.split(",")
            new Tuple3[String, String, String](word(0), word(1), word(2))
          }
        })
        tableEnv.createTemporaryView("Table1", kafkaStream, $("name"), $("age"), $("sexy"), $("proctime").proctime)
        val socketStream = env.socketTextStream(hostname, port, "\n").map(new MapFunction[String, Tuple2[String, String]]() {
          @throws[Exception]
          override def map(str: String): Tuple2[String, String] = {
            val words = str.split("\\s")
            if (words.length < 2) return new Tuple2[String, String]
            new Tuple2[String, String](words(0), words(1))
          }
        })
        tableEnv.createTemporaryView("Table2", socketStream, $("name"), $("job"), $("proctime").proctime)
        val result = tableEnv.sqlQuery("SELECT t1.name, t1.age, t1.sexy, t2.job, t2.proctime as shiptime\n" + "FROM Table1 AS t1\n" + "JOIN Table2 AS t2\n" + "ON t1.name = t2.name\n" + "AND t1.proctime BETWEEN t2.proctime - INTERVAL '1' SECOND AND t2.proctime + INTERVAL" + " '1' SECOND")
        tableEnv.toAppendStream(result, classOf[Row]).print
        env.execute
      }
    }
   ```