九、Sink详解

一、PrintSink

printSink并行度默认和cpu核数相关，传参标识符默认添加到首字符里

        DataStreamSource<String> source = env.socketTextStream("192.168.87.130", 8888);
        
        source.print("res");
        env.execute("PrintSink");

输入：

aaaa
bbb
ccccc

输出：

res:4> aaaa
res:1> bbb
res:2> ccccc

二、自定义sink(addSink)

        DataStream<String> lines = env.socketTextStream("192.168.87.130", 8888);
        
        SingleOutputStreamOperator<Tuple2<String, Integer>> wordAndOne = lines.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
            @Override
            public void flatMap(String line,
                    Collector<Tuple2<String, Integer>> out) throws Exception {
                String[] words = line.split(" ");
                for(String word : words) {
                     Tuple2<String, Integer> tp = Tuple2.of(word, 1);
                     out.collect(tp);
                }
            }
        });
        
        
        SingleOutputStreamOperator<Tuple2<String, Integer>> sumned = wordAndOne.keyBy(0).sum(1);
        
        sumned.addSink(new RichSinkFunction<Tuple2<String,Integer>>() {
            @Override
            public void invoke(
                    Tuple2<String, Integer> value, Context context)
                    throws Exception {
                int index = getRuntimeContext().getIndexOfThisSubtask();
                System.out.println(index + ">" + value);
            }
        });

输入：

aaaa
bbb
ccccc
spark flink spring spark
spring spring flink

输出：

0>(spark,1)
3>(flink,1)
2>(spring,1)
0>(spark,2)
3>(flink,2)
2>(spring,2)
2>(spring,3)

三、writeAsCsv

只能用于tuple类型的data streams，默认4096个字节才会写入csv中