【Flink】转换算子 flatMap

一、实体类

@Data
public class Event {
    public String user;
    public String url;
    public Long timestamp;
    
    public Event(String user, String url, Long timestamp) {
        this.user = user;
        this.url = url;
        this.timestamp = timestamp;
    }
}

二、自定义数据源模拟流式数据

public class ClickSource implements SourceFunction {
 
    //声明一个标志类
    private Boolean running = true;
 
    @Override
    public void run(SourceContext ctx) throws Exception {
        //随机生成数据
        Random random = new Random();
 
        //定义字段选取的数据集
        String[] users = {"Mary","Alice","Bob","Cary"};
        String[] urls = {"./home","./cart","./fav","./prod?id=100","./prod:id=10"};
 
        //循环生成数据
        while (running){
            String user = users[random.nextInt(users.length)];
            String url = urls[random.nextInt(user.length())];
            Long time = System.currentTimeMillis();
            ctx.collect(new Event(user,url,time));
            Thread.sleep(2000);
        }
    }
 
    @Override
    public void cancel() {
        running = false;
    }
}

三、任务代码

public class TransFormFlatMapTest {
    public static void main(String[] args) throws Exception {
        //创建执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        //设置并行度
        env.setParallelism(1);

        //读取数据源
        DataStreamSource dataStream = env.addSource(new ClickSource());

        //进行转换操作 扁平映射
        SingleOutputStreamOperator flatMap = dataStream.flatMap(new FlatMapFunction() {
            @Override
            public void flatMap(Event event, Collector collector) throws Exception {
                if (event.user.equals("Bob")) {
                    collector.collect(event.url);
                }
            }
        });

        //打印
        flatMap.print();

        //开始
        env.execute();
    }
}