Flink CEP 空气质量监控案例

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本文介绍了一个使用 Apache Flink CEP 进行空气质量监测的应用案例。通过从 Kafka 消费数据，定义复杂的事件模式来识别空气质量的变化趋势，并对不同类型的预警进行分类。

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实际业务场景代码会比这个复制，但是类似............

package wang.datahub.cep;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.cep.CEP;
import org.apache.flink.cep.PatternStream;
import org.apache.flink.cep.pattern.Pattern;
import org.apache.flink.cep.pattern.conditions.IterativeCondition;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer010;
import wang.datahub.cep.event.AirQualityRecoder;
import wang.datahub.cep.event.AirWarningRecoder;
import wang.datahub.cep.event.AirWarningTypeRecoder;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class CepApp {
public static void main(String[] args) throws Exception {
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
Map properties= new HashMap();
properties.put("bootstrap.servers", "localhost:9092");
properties.put("group.id", "test");
properties.put("enable.auto.commit", "true");
properties.put("auto.commit.interval.ms", "1000");
properties.put("auto.offset.reset", "earliest");
properties.put("session.timeout.ms", "30000");
// properties.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
// properties.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
properties.put("topic", "test1");
ParameterTool parameterTool = ParameterTool.fromMap(properties);
FlinkKafkaConsumer010 consumer010 = new FlinkKafkaConsumer010(
parameterTool.getRequired("topic"), new WriteIntoKafka.SimpleAirQualityRecoderSchema(), parameterTool.getProperties());
DataStream<AirQualityRecoder> aqrStream = env
.addSource(consumer010);
Pattern<AirQualityRecoder, ?> warningPattern = Pattern.<AirQualityRecoder>begin("first")
.subtype(AirQualityRecoder.class)
.where(new IterativeCondition<AirQualityRecoder>(){
@Override
public boolean filter(AirQualityRecoder value, Context<AirQualityRecoder> ctx) throws Exception {
return value.getAirQuality() >= 6;
}
}).or(new IterativeCondition<AirQualityRecoder>(){
@Override
public boolean filter(AirQualityRecoder value, Context<AirQualityRecoder> ctx) throws Exception {
return value.getAirQuality() <= 3;
}
})

.next("second")
.where(new IterativeCondition<AirQualityRecoder>(){
@Override
public boolean filter(AirQualityRecoder value, Context<AirQualityRecoder> ctx) throws Exception {
return value.getAirQuality() >= 7;
}
}).or(new IterativeCondition<AirQualityRecoder>(){
@Override
public boolean filter(AirQualityRecoder value, Context<AirQualityRecoder> ctx) throws Exception {
return value.getAirQuality() <= 2;
}
})
.within(Time.seconds(60))
;
PatternStream<AirQualityRecoder> warningPatternStream = CEP.pattern(
aqrStream.keyBy("city"),//"city"
warningPattern);
DataStream<AirWarningRecoder> warnings = warningPatternStream.select(
(Map<String, List<AirQualityRecoder>> pattern) -> {
AirQualityRecoder first = (AirQualityRecoder) pattern.get("first").get(0);
AirQualityRecoder second = (AirQualityRecoder) pattern.get("second").get(0);
return new AirWarningRecoder(first.getCity(),first,second);
}
);
Pattern<AirWarningRecoder, ?> typePattern = Pattern.<AirWarningRecoder>begin("pass")
.subtype(AirWarningRecoder.class);

PatternStream<AirWarningRecoder> typePatternStream = CEP.pattern(
warnings.keyBy(AirWarningRecoder::getCity),
typePattern
);
DataStream<AirWarningTypeRecoder> awt = typePatternStream.select(
(Map<String, List<AirWarningRecoder>> pattern) -> {
AirWarningRecoder awr = (AirWarningRecoder) pattern.get("pass").get(0);
AirWarningTypeRecoder awtr = new AirWarningTypeRecoder();
awtr.setCity(awr.getCity());
awtr.setFirst(awr.getFirst().getAirQuality());
awtr.setSecond(awr.getSecond().getAirQuality());
int res = Math.abs(awtr.getFirst()-awtr.getSecond());
if(res <=2){
awtr.setWtype("质量超标");
}else{
awtr.setWtype("波动较大");
}

return awtr;
}
);
warnings.print();
awt.print();
env.execute("cep run!!!");
}
}