项目中flink cep的4个流程及代码

Flink CEP（Complex Event Processing）是一种处理事件流的框架，它可以对事件流进行基于时间窗口、模式匹配和复杂事件处理等操作。下面是Flink CEP的4个流程及相应的代码示例。

定义输入流

首先，需要定义输入流，这可以通过Flink的DataStream API来实现。以下是一个示例代码，它定义了一个名为“inputStream”的输入流，该流包含了一组事件数据，每个事件包含了一个名称和一个时间戳。

DataStream<Event> inputStream = env.fromElements(
    new Event("event1", 1000),
    new Event("event2", 2000),
    new Event("event3", 3000),
    new Event("event4", 4000),
    new Event("event5", 5000),
    new Event("event6", 6000),
    new Event("event7", 7000)
);

定义模式

接下来，需要定义待匹配的模式。模式是由一组事件组成的序列，这些事件按特定的规则进行匹配。例如，以下代码定义了一个模式，该模式匹配了一个名为“event1”的事件，后跟一个名为“event2”的事件，并且这两个事件之间的时间间隔不超过2秒。

Pattern<Event, ?> pattern = Pattern.<Event>begin("start")
    .where(new SimpleCondition<Event>() {
        @Override
        public boolean filter(Event event) {
            return event.getName().equals("event1");
        }
    })
    .followedBy("middle")
    .where(new SimpleCondition<Event>() {
        @Override
        public boolean filter(Event event) {
            return event.getName().equals("event2");
        }
    })
    .within(Time.seconds(2));

应用模式

一旦定义了模式，就可以将其应用到输入流上，以查找与模式匹配的事件序列。以下是一个示例代码，它使用Flink CEP的“pattern”函数来应用模式，并将匹配结果保存到一个名为“resultStream”的输出流中。

PatternStream<Event> patternStream = CEP.pattern(inputStream.keyBy(Event::getName), pattern);
DataStream<String> resultStream = patternStream.select((Map<String, List<Event>> patternMatch) -> {
    Event startEvent = patternMatch.get("start").get(0);
    Event middleEvent = patternMatch.get("middle").get(0);
    return startEvent.getName() + "-" + middleEvent.getName();
});

输出结果

最后，可以将结果输出到控制台或保存到文件中。以下是一个示例代码，它将结果输出到控制台。

resultStream.print();

完整代码示例：

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.functions.SimpleFunction;
import org.apache.flink.api.common.state.ValueState;
import org.apache.flink.api.common.state.ValueStateDescriptor;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.api.java.tuple.Tuple2;
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.SimpleCondition;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.AssignerWithPeriodicWatermarks;
import org.apache.flink.streaming.api.watermark.Watermark;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.util.Collector;

import javax.annotation.Nullable;
import java.text.SimpleDateFormat;
import java.util.*;

public class FlinkCEPExample {
    public static void main(String[] args) throws Exception {
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        DataStream<Event> inputStream = env.fromElements(
                new Event("event1", 1000),
                new Event("event2", 2000),
                new Event("event3", 3000),
                new Event("event4", 4000),
                new Event("event5", 5000),
                new Event("event6", 6000),
                new Event("event7", 7000)
        );

        Pattern<Event, ?> pattern = Pattern.<Event>begin("start")
                .where(new SimpleCondition<Event>() {
                    @Override
                    public boolean filter(Event event) {
                        return event.getName().equals("event1");
                    }
                })
                .followedBy("middle")
                .where(new SimpleCondition<Event>() {
                    @Override
                    public boolean filter(Event event) {
                        return event.getName().equals("event2");
                    }
                })
                .within(Time.seconds(2));

        PatternStream<Event> patternStream = CEP.pattern(inputStream.keyBy(Event::getName), pattern);
        DataStream<String> resultStream = patternStream.select((Map<String, List<Event>> patternMatch) -> {
            Event startEvent = patternMatch.get("start").get(0);
            Event middleEvent = patternMatch.get("middle").get(0);
            return startEvent.getName() + "-" + middleEvent.getName();
        });

        resultStream.print();

        env.execute("Flink CEP Example");
    }

    public static class Event {
        private String name;
        private long timestamp;

        public Event() {}

        public Event(String name, long timestamp) {
            this.name = name;
            this.timestamp = timestamp;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public long getTimestamp() {
            return timestamp;
        }

        public void setTimestamp(long timestamp) {
            this.timestamp = timestamp;
        }

        @Override
        public String toString() {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
            return "Event{" +
                    "name='" + name + '\'' +
                    ", timestamp=" + sdf.format(new Date(timestamp)) +
                    '}';
        }
    }
}
``