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在flink中#xff0c;如果你想要访问记录的处理时间或者事件时间#xff0c;注册定时器#xff0c;或者是将记录输出到多个输出流中#xff0c;你都需要处理函数的帮助#xff0c;本文就来通过一个例子来讲解下副输出
副输出
本文还是基于streaming-with-flink这本…背景
在flink中如果你想要访问记录的处理时间或者事件时间注册定时器或者是将记录输出到多个输出流中你都需要处理函数的帮助本文就来通过一个例子来讲解下副输出
副输出
本文还是基于streaming-with-flink这本书的例子作为演示它实现一个把温度低于32度的记录输出到副输出的功能正常的记录还是从主输出中输出.代码如下
package wikiedits.processfunc.job;import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.OutputTag;import wikiedits.processfunc.pojo.SensorReading;
import wikiedits.processfunc.process.FreezingMonitor;
import wikiedits.processfunc.source.SensorSource;public class SideOutPutJob {public static void main(String[] args) throws Exception {StreamExecutionEnvironment see StreamExecutionEnvironment.getExecutionEnvironment();DataStreamSensorReading readings see.addSource(new SensorSource());SingleOutputStreamOperatorSensorReading monitoredReadings readings.process(new FreezingMonitor());// 打印附输出monitoredReadings.getSideOutput(new OutputTagString(freezing-alarms){}).print();// 打印主输出monitoredReadings.print();see.execute();}
}package wikiedits.processfunc.process;import org.apache.flink.streaming.api.functions.ProcessFunction;
import org.apache.flink.util.Collector;
import org.apache.flink.util.OutputTag;import wikiedits.processfunc.pojo.SensorReading;public class FreezingMonitor extends ProcessFunctionSensorReading, SensorReading {private OutputTagString freezingAlarmOutput new OutputTagString(freezing-alarms) {};Overridepublic void processElement(SensorReading value, Context ctx, CollectorSensorReading out) throws Exception {if (value.temperature 32.0) {ctx.output(freezingAlarmOutput, freezing alarm for value.id : value.temperature);}out.collect(value);}}
package wikiedits.processfunc.source;/** Copyright 2015 Fabian Hueske / Vasia Kalavri** Licensed under the Apache License, Version 2.0 (the License);* you may not use this file except in compliance with the License.* You may obtain a copy of the License at** http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an AS IS BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/
import org.apache.flink.streaming.api.functions.source.RichParallelSourceFunction;
import wikiedits.processfunc.pojo.SensorReading;import java.util.Calendar;
import java.util.Random;/*** Flink SourceFunction to generate SensorReadings with random temperature values.** Each parallel instance of the source simulates 10 sensors which emit one sensor reading every 100 ms.** Note: This is a simple data-generating source function that does not checkpoint its state.* In case of a failure, the source does not replay any data.*/
public class SensorSource extends RichParallelSourceFunctionSensorReading {// flag indicating whether source is still runningprivate boolean running true;/** run() continuously emits SensorReadings by emitting them through the SourceContext. */Overridepublic void run(SourceContextSensorReading srcCtx) throws Exception {// initialize random number generatorRandom rand new Random();// look up index of this parallel taskint taskIdx this.getRuntimeContext().getIndexOfThisSubtask();// initialize sensor ids and temperaturesString[] sensorIds new String[10];double[] curFTemp new double[10];for (int i 0; i 10; i) {sensorIds[i] sensor_ (taskIdx * 10 i);curFTemp[i] 65 (rand.nextGaussian() * 20);}while (running) {// get current timelong curTime Calendar.getInstance().getTimeInMillis();// emit SensorReadingsfor (int i 0; i 10; i) {// update current temperaturecurFTemp[i] rand.nextGaussian() * 0.5;// emit readingsrcCtx.collect(new SensorReading(sensorIds[i], curTime, curFTemp[i]));}// wait for 100 msThread.sleep(3000);}}/** Cancels this SourceFunction. */Overridepublic void cancel() {this.running false;}
}
程序运行结果
