Code Walkthroughs DataStream API

上级：https://www.cnblogs.com/hackerxiaoyon/p/12747387.html

DataStream API

　　DataStreamApi 提供了健壮，有状态的流应用，提供了细力度的控制基于状态和时间，事件驱动系统中可以高级实现。通过DataStreamApi 一步一步的向导我们可以学习到一个有状态的流应用。

What Are You Building ？

　　通过信用卡交易监控例子，用一个简单的规则set，让我们可以看到flink是如何实现实时业务操作的。

Prerequisites 前提

　　这段代码的演示需要你具备了java 或者 scala的知识，但是你如果你有其他的编程语言能力也是可以的。

Help,I’m Stuck! 寻求帮助

　　如果你卡住了，可以求助 https://flink.apache.org/gettinghelp.html 。https://flink.apache.org/community.html#mailing-lists 用户邮件列表是一个活跃快速提供帮助的地方。

How to Follow Along 如何跟进

　　有一些电脑配置：

　　　　Java 8 或者 11 这里官网没有说别的

　　　　Maven

　　然后是构建项目：java 和 scala 各一份

$ mvn archetype:generate \

-DarchetypeGroupId=org.apache.flink \

-DarchetypeArtifactId=flink-walkthrough-datastream-java \

-DarchetypeVersion=1.10.0 \

-DgroupId=frauddetection \

-DartifactId=frauddetection \

-Dversion=0.1 \

-Dpackage=spendreport \

-DinteractiveMode=false

$ mvn archetype:generate \

-DarchetypeGroupId=org.apache.flink \

-DarchetypeArtifactId=flink-walkthrough-datastream-scala \

-DarchetypeVersion=1.10.0 \

-DgroupId=frauddetection \

-DartifactId=frauddetection \

-Dversion=0.1 \

-Dpackage=spendreport \

-DinteractiveMode=false

　　之后代码生成了，我们直接看代码。那么如何跟进的演示代码就这样结束了。

FraudDetectionJob.java

package spendreport;

import org.apache.flink.streaming.api.datastream.DataStream;import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;import org.apache.flink.walkthrough.common.sink.AlertSink;import org.apache.flink.walkthrough.common.entity.Alert;import org.apache.flink.walkthrough.common.entity.Transaction;import org.apache.flink.walkthrough.common.source.TransactionSource;

public class FraudDetectionJob {

public static void main(String[] args) throws Exception {

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

DataStream<Transaction> transactions = env

.addSource(new TransactionSource())

.name("transactions");

DataStream<Alert> alerts = transactions

.keyBy(Transaction::getAccountId)

.process(new FraudDetector())

.name("fraud-detector");

alerts

.addSink(new AlertSink())

.name("send-alerts");

env.execute("Fraud Detection");

}}

FraudDetector.java

package spendreport;

import org.apache.flink.streaming.api.functions.KeyedProcessFunction;import org.apache.flink.util.Collector;import org.apache.flink.walkthrough.common.entity.Alert;import org.apache.flink.walkthrough.common.entity.Transaction;

public class FraudDetector extends KeyedProcessFunction<Long, Transaction, Alert> {

private static final long serialVersionUID = 1L;

private static final double SMALL_AMOUNT = 1.00;

private static final double LARGE_AMOUNT = 500.00;

private static final long ONE_MINUTE = 60 * 1000;

@Override

public void processElement(

Transaction transaction,

Context context,

Collector<Alert> collector) throws Exception {

Alert alert = new Alert();

alert.setId(transaction.getAccountId());

collector.collect(alert);

}}

FraudDetectionJob.scala

package spendreport

import org.apache.flink.streaming.api.scala._import org.apache.flink.walkthrough.common.sink.AlertSinkimport org.apache.flink.walkthrough.common.entity.Alertimport org.apache.flink.walkthrough.common.entity.Transaction

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