flink-demo 基于 DataStream API 实现欺诈检测

flink

诈骗发现

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");
	}
}

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;

	private transient ValueState<Boolean> flagState;
	private transient ValueState<Long> timerState;

	@Override
	public void open(Configuration parameters) throws Exception {
		ValueStateDescriptor<Boolean> flagDescriptor = new ValueStateDescriptor<>("flag", Types.BOOLEAN);
		flagState = getRuntimeContext().getState(flagDescriptor);

		ValueStateDescriptor<Long> timerDescriptor = new ValueStateDescriptor<>("timer", Types.LONG);
		timerState = getRuntimeContext().getState(timerDescriptor);
	}

	@Override
	public void processElement(
			Transaction transaction,
			Context context,
			Collector<Alert> collector) throws Exception {

		Boolean flag = flagState.value();
		if (flag != null) {
			if (transaction.getAmount() > LARGE_AMOUNT) {
				Alert alert = new Alert();
				alert.setId(transaction.getAccountId());

				collector.collect(alert);
			}

			// 不管超过LARGE_AMOUNT还是没有，都要clear
			flagState.clear();

			long timer = timerState.value();
			context.timerService().deleteProcessingTimeTimer(timer);
			timerState.clear();
		}

		if (transaction.getAmount() < SMALL_AMOUNT) {
			flagState.update(true);

			long timer = context.timerService().currentProcessingTime() + ONE_MINUTE;
			context.timerService().registerProcessingTimeTimer(timer);
			timerState.update(timer);
		}
	}


	/**
	 * 如果1分钟内没有交易，直接清空。
	 * 也就是，仅对1分钟内的小额、大额交易判定为诈骗
	 */
	@Override
	public void onTimer(long timestamp, KeyedProcessFunction<Long, Transaction, Alert>.OnTimerContext ctx, Collector<Alert> out) throws Exception {
		System.out.println("onTimer");
		flagState.clear();
		timerState.clear();
	}
}

参考

• 基于 DataStream API 实现欺诈检测