Flink自定义非并行的Source，即Source的并行度只为1

自定义非并行的Source，即Source的并行度只为1

如果实现了SourceFunction接口或继承了RichSourceFunction抽象类，得到的DataStream为只有一个并行；

import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.source.SourceFunction;


public class CustomerNonParallelSource {
    public static void main(String[] args) throws Exception {
        Configuration configuration = new Configuration();
        configuration.setInteger("rest.port", 8081);
        StreamExecutionEnvironment env = StreamExecutionEnvironment.createLocalEnvironmentWithWebUI(configuration);
        DataStreamSource nums = env.addSource(new NonParallelSourceFunc());


        System.out.println("自定义NonParallelSourceFunc得到的DataStream的并行度为：" + nums.getParallelism());
        nums.print();
        env.execute();

    }
    private static class NonParallelSourceFunc implements SourceFunction {


        
        @Override
        public void run(SourceContext ctx) throws Exception {
            System.out.println("Run方法被调用了~~~~~");
            for (int i = 0; i < 100; i++) {
                //Source产生的数据使用SourceContext将数据输出
                ctx.collect(i);
            }
        }

        
        @Override
        public void cancel() {
            System.out.println("Cancel方法被调用了~~~~~");
        }
    }
}