Keyed Value State

package com.atguigu.state;

import com.atguigu.bean.WaterSensor;
import com.atguigu.functions.WaterSensorMapFunction;
import org.apache.flink.api.common.eventtime.WatermarkStrategy;
import org.apache.flink.api.common.state.ValueState;
import org.apache.flink.api.common.state.ValueStateDescriptor;
import org.apache.flink.api.common.typeinfo.Types;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.KeyedProcessFunction;
import org.apache.flink.util.Collector;

import java.time.Duration;

/**
 * TODO 检测每种传感器的水位值，如果连续的两个水位值超过10，就输出报警
 */
public class KeyedValueStateDemo {
    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(1);

        SingleOutputStreamOperator<WaterSensor> sensorDS = env
                .socketTextStream("192.168.1.7", 9091)
                .map(new WaterSensorMapFunction())
                .assignTimestampsAndWatermarks(
                        WatermarkStrategy
                                .<WaterSensor>forBoundedOutOfOrderness(Duration.ofSeconds(3))
                                .withTimestampAssigner((element, ts) -> element.getTs() * 1000L)
                );

        sensorDS.keyBy(r -> r.getId())
                .process(
                        new KeyedProcessFunction<String, WaterSensor, String>() {

                            // TODO 1.定义状态
                            ValueState<Integer> lastVcState;

                            @Override
                            public void open(Configuration parameters) throws Exception {
                                super.open(parameters);
                                // TODO 2.在open方法中，初始化状态
                                // 状态描述器两个参数：第一个参数，起个名字，不重复；第二个参数，存储的类型
                                lastVcState = getRuntimeContext().getState(new ValueStateDescriptor<Integer>("lastVcState", Types.INT));
                            }

                            @Override
                            public void processElement(WaterSensor value, Context ctx, Collector<String> out) throws Exception {
                                //lastVcState.value();  // 取出 本组 值状态 的数据
                                //lastVcState.update(); // 更新 本组 值状态 的数据
                                //lastVcState.clear();  // 清除 本组 值状态 的数据

                                // 1. 取出上一条数据的水位值(Integer默认值是null，判断)
                                int lastVc = lastVcState.value() == null ? 0 : lastVcState.value();
                                // 2. 求差值的绝对值，判断是否超过10
                                Integer vc = value.getVc();
                                if (Math.abs(vc - lastVc) > 10) {
                                    out.collect("传感器=" + value.getId() + "==>当前水位值=" + vc + ",与上一条水位值=" + lastVc + ",相差超过10！！！！");
                                }
                                // 3. 更新状态里的水位值
                                lastVcState.update(vc);
                            }
                        }
                )
                .print();

        env.execute();
    }
}