本章节主要演示从socket接收数据，通过滚动窗口每30秒运算一次窗口数据，然后将结果写入Mysql数据库

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（1）准备一个实体对象，消息对象

package com.pojo;

import java.io.Serializable;

/**
 * Created by lj on 2022-07-05.
 */
public class WaterSensor implements Serializable {
    private String id;
    private long ts;
    private 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;
    }
}

（2）编写socket代码，模拟数据发送

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 2022-07-05.
 */
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();   
            String[] lang = {"flink","spark","hadoop","hive","hbase","impala","presto","superset","nbi"};

            while(true){
                Thread.sleep(2000);
                response= lang[r.nextInt(lang.length)] + "," + i + "," + i+"\n";
                System.out.println(response);
                try{
                    bw.write(response);
                    bw.flush();
                    i++;
                }catch (Exception ex){
                    System.out.println(ex.getMessage());
                }

            }
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

（3）从socket端接收数据，并设置30秒触发执行一次窗口运算

package com.examples;

import com.pojo.WaterSensor;
import com.sinks.RetractStream_Mysql;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.table.api.Table;
import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
import org.apache.flink.types.Row;

import static org.apache.flink.table.api.Expressions.$;

/**
 * Created by lj on 2022-07-06.
 */

public class Flink_Group_Window_Tumble_Sink_Mysql {
    public static void main(String[] args) throws Exception {

        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(1);
        StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env);
        DataStreamSource<String> streamSource = env.socketTextStream("127.0.0.1", 9999,"\n");
        SingleOutputStreamOperator<WaterSensor> waterDS = streamSource.map(new MapFunction<String, WaterSensor>() {
            @Override
            public WaterSensor map(String s) throws Exception {
                String[] split = s.split(",");
                return new WaterSensor(split[0], Long.parseLong(split[1]), Integer.parseInt(split[2]));
            }
        });

        // 将流转化为表
        Table table = tableEnv.fromDataStream(waterDS,
                $("id"),
                $("ts"),
                $("vc"),
                $("pt").proctime());

        tableEnv.createTemporaryView("EventTable", table);

        Table result = tableEnv.sqlQuery(
                "SELECT " +
                        "id, " +                //window_start, window_end,
                        "COUNT(ts) ,SUM(ts)" +
                        "FROM TABLE( " +
                        "TUMBLE( TABLE EventTable , " +
                        "DESCRIPTOR(pt), " +
                        "INTERVAL '30' SECOND)) " +
                        "GROUP BY id , window_start, window_end"
        );

        tableEnv.toRetractStream(result, Row.class).addSink(new RetractStream_Mysql()); 
        env.execute();
    }
}

（4）定义一个写入到mysql的sink

package com.sinks;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.functions.sink.RichSinkFunction;
import org.apache.flink.types.Row;

/**
 * Created by lj on 2022-07-06.
 */
public class RetractStream_Mysql  extends RichSinkFunction<Tuple2<Boolean, Row>> {

    private static final long serialVersionUID = -4443175430371919407L;
    PreparedStatement ps;
    private Connection connection;

    /**
     * open() 方法中建立连接，这样不用每次 invoke 的时候都要建立连接和释放连接
     *
     * @param parameters
     * @throws Exception
     */
    @Override
    public void open(Configuration parameters) throws Exception {
        super.open(parameters);
        connection = getConnection();
    }

    @Override
    public void close() throws Exception {
        super.close();
        //关闭连接和释放资源
        if (connection != null) {
            connection.close();
        }
        if (ps != null) {
            ps.close();
        }
    }

    /**
     * 每条数据的插入都要调用一次 invoke() 方法
     *
     * @param context
     * @throws Exception
     */
    @Override
    public void invoke(Tuple2<Boolean, Row> userPvEntity, Context context) throws Exception {
        String sql = "INSERT INTO flinkcomponent(componentname,componentcount,componentsum) VALUES(?,?,?);";
        ps = this.connection.prepareStatement(sql);

        ps.setString(1,userPvEntity.f1.getField(0).toString());
        ps.setInt(2, Integer.parseInt(userPvEntity.f1.getField(1).toString()));
        ps.setInt(3, Integer.parseInt(userPvEntity.f1.getField(2).toString()));
        ps.executeUpdate();
    }

    private static Connection getConnection() {
        Connection con = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/testdb?useUnicode=true&characterEncoding=UTF-8&useSSL=false","root","root");
        } catch (Exception e) {
            System.out.println("-----------mysql get connection has exception , msg = "+ e.getMessage());
        }
        return con;
    }
}

（5）效果演示，每30秒往数据库写一次数据

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