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一、说明

基于处理时间或者事件时间处理过一个元素之后, 注册一个定时器, 然后指定的时间执行.
Context和OnTimerContext所持有的TimerService对象拥有以下方法:
currentProcessingTime(): Long 返回当前处理时间
currentWatermark(): Long 返回当前watermark的时间戳
registerProcessingTimeTimer(timestamp: Long): Unit 会注册当前key的processing time的定时器。当processing time到达定时时间时，触发timer。
registerEventTimeTimer(timestamp: Long): Unit 会注册当前key的event time 定时器。当水位线大于等于定时器注册的时间时，触发定时器执行回调函数。
deleteProcessingTimeTimer(timestamp: Long): Unit 删除之前注册处理时间定时器。如果没有这个时间戳的定时器，则不执行。
deleteEventTimeTimer(timestamp: Long): Unit 删除之前注册的事件时间定时器，如果没有此时间戳的定时器，则不执行。

二、基于处理时间的定时器

package com.lyh.flink08;import com.lyh.bean.WaterSensor;
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;public class ProcessTime {public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();env.setParallelism(1);SingleOutputStreamOperator<WaterSensor> stream = env.socketTextStream("hadoop100", 9999).map(line -> {String[] datas = line.split(",");return new WaterSensor(datas[0],Long.valueOf(datas[1]),Integer.valueOf(datas[2]));});stream.keyBy(WaterSensor::getId).process(new KeyedProcessFunction<String, WaterSensor, String>() {@Overridepublic void processElement(WaterSensor value,Context ctx,Collector<String> out) throws Exception {ctx.timerService().registerProcessingTimeTimer(ctx.timerService().currentProcessingTime() + 5000);out.collect(value.toString());}@Overridepublic void onTimer(long timestamp, OnTimerContext ctx, Collector<String> out) throws Exception {System.out.println(timestamp);out.collect("wo be chu fa le ");}}).print();env.execute();}
}

三、基于事件时间的定时器

package com.lyh.flink08;import com.lyh.bean.WaterSensor;
import org.apache.flink.api.common.eventtime.WatermarkStrategy;
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;public class EventTime_s {public static void main(String[] args) throws Exception {StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();env.setParallelism(1);SingleOutputStreamOperator<WaterSensor> stream = env.socketTextStream("hadoop100", 9999).map(line -> {String[] datas = line.split(",");return new WaterSensor(datas[0],Long.valueOf(datas[1]),Integer.valueOf(datas[2]));});WatermarkStrategy<WaterSensor> wms = WatermarkStrategy.<WaterSensor>forBoundedOutOfOrderness(Duration.ofSeconds(3)).withTimestampAssigner((element,recordTimestamp) -> element.getTs() * 1000);stream.assignTimestampsAndWatermarks(wms).keyBy(WaterSensor::getId).process(new KeyedProcessFunction<String, WaterSensor, String>() {@Overridepublic void processElement(WaterSensor value,Context ctx,Collector<String> out) throws Exception {System.out.println(ctx.timestamp());ctx.timerService().registerProcessingTimeTimer(ctx.timestamp()+5000);out.collect(value.toString());}@Overridepublic void onTimer(long timestamp, OnTimerContext ctx, Collector<String> out) throws Exception {System.out.println("定时器被触发了");}}).print();env.execute();}
}