flink官方示例分析-基于 DataStream API 实现欺诈检测

看到这篇文章，应该都是看过flink官网的官方示例，这里就不作详细解释，只对其中的代码细节补充个人理解。如果还没看过，可以先看官方示例。

官方示例
api

pom文件

    <properties>
        <java.version>1.8</java.version>
        <flink.version>1.12.0</flink.version>
        <scala.binary.version>2.11</scala.binary.version>
        <scala.version>2.11.12</scala.version>
    </properties>

   <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-walkthrough-common_${
   scala.binary.version}</artifactId>
            <version>${
   flink.version}</version>
        </dependency>

        <!-- Apache Flink dependencies -->
        <!-- These dependencies are provided, because they should not be packaged into the JAR file. -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-scala_${
   scala.binary.version}</artifactId>
            <version>${
   flink.version}</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients_${
   scala.binary