Flink状态应用测试程序示例

Flink状态应用测试程序示例

1. 创建执行环境

        // 1. 创建执行环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(1);   

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2. 创建数据流

        // 2. 创建数据流
        DataStream<Tuple2<String, Integer>> inputStream = env.fromElements(
                Tuple2.of("a", 1),
                Tuple2.of("b", 2),
                Tuple2.of("c", 3),
                Tuple2.of("a", 4),
                Tuple2.of("b", 5),
                Tuple2.of("c", 6)
        ).uid("source").name("source");

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3. 对数据流进行keyBy()操作

        // 3. 对数据流进行keyBy()操作
        DataStream<Tuple2<String, Integer>> keyedStream = inputStream.keyBy(new KeySelector<Tuple2<String, Integer>, String>() {
            @Override
            public String getKey(Tuple2<String, Integer> stringIntegerTuple2) throws Exception {
                return stringIntegerTuple2.f0;
            }
        });

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4. 使用RichFlatMapFunction来实现状态的维护

        // 4. 使用RichFlatMapFunction来实现状态的维护
        keyedStream.flatMap(new RichFlatMapFunction<Tuple2<String, Integer>, Tuple2<String, Integer>>() {
            // 定义状态变量
            private ValueState<Integer> countState;
            @Override
            public void open(Configuration parameters) throws Exception {
                // 初始化状态变量
                ValueStateDescriptor<Integer> descriptor = new ValueStateDescriptor<>("count", Integer.class);
                countState = getRuntimeContext().getState(descriptor);
            }

            @Override
            public void flatMap(Tuple2<String, Integer> input, Collector<Tuple2<String, Integer>> out) throws Exception {
                // 获取状态变量的值
                Integer currentCount = countState.value();

                // 更新状态变量的值
                if (currentCount == null) {
                    currentCount = 0;
                }
                currentCount++;
                countState.update(currentCount);

                // 输出结果
                out.collect(Tuple2.of(input.f0, currentCount));
            }
        }).print(); 

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5.执行任务

        // 5.执行任务
        env.execute("Flink State Test"); 

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6.执行结果

(a,1)
(b,1)
(c,1)
(a,2)
(b,2)
(c,2)

Process finished with exit code 0

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