本小节展示storm流式计算中的滑动窗口，我们将使用本地模式运行storm。

1、操作步骤

• 创建一个maven工程，加入以下依赖：

<dependency>
            <groupId>org.apache.storm</groupId>
            <artifactId>storm-core</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>log4j-over-slf4j</artifactId>
                </exclusion>
            </exclusions>
            <version>1.2.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.storm</groupId>
            <artifactId>storm-kafka-client</artifactId>
            <version>1.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
            <version>0.10.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.storm</groupId>
            <artifactId>storm-kafka</artifactId>
            <version>1.2.1</version>
        </dependency>

• 在项目的src/main/java文件夹下创建InputSpout.java

import java.util.Map;
import java.util.Random;
import java.util.Scanner;

import org.apache.storm.spout.SpoutOutputCollector;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.base.BaseRichSpout;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Values;

public class InputSpout extends BaseRichSpout {
    SpoutOutputCollector _collector;
    Random _rand;

    public void open(Map conf, TopologyContext context, SpoutOutputCollector collector) {
        _collector = collector;
        _rand = new Random();
    }

    public void nextTuple() {

        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入一个单词");
        String sentence = scanner.nextLine();
        _collector.emit(new Values(sentence));
    }

    public void ack(Object id) {
    }

    public void fail(Object id) {
    }

    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("word"));
    }
}

• 在项目的src/main/java文件夹下创建SlidingWindowDemo.java

import org.apache.storm.Config;
import org.apache.storm.LocalCluster;
import org.apache.storm.task.OutputCollector;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.topology.TopologyBuilder;
import org.apache.storm.topology.base.BaseWindowedBolt;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.windowing.TupleWindow;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class SlidingWindowDemo extends BaseWindowedBolt {
    private OutputCollector collector;

    @Override
    public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
        this.collector = collector;
    }

    @Override
    public void execute(TupleWindow inputWindow) {
        Map<String, Integer> counts = new HashMap<String, Integer>();
        List<Tuple> tuples = inputWindow.get();
        String word = "";
        Integer count = 0;
        for (Tuple tuple : tuples) {
            word = tuple.getString(0);
            count = counts.get(tuple.getString(0));
            if (count == null) {
                count = 0;
            }
            count++;
            counts.put(word, count);
        }
        System.out.println(counts);
    }

    public static void main(String[] args) throws Exception {
        TopologyBuilder builder = new TopologyBuilder();
        builder.setSpout("spout", new InputSpout(), 1);
        //按消息个数滑动
//        builder.setBolt("slidingwindowbolt",
//                new SlidingWindowDemo().withWindow(new Count(30), new Count(10)),
//                1).shuffleGrouping("spout");
        //按时间长短滑动
        builder.setBolt("slidingwindowbolt",
                new SlidingWindowDemo().withWindow(new Count(30), Duration.seconds(10)),
                1).shuffleGrouping("spout");
        Config conf = new Config();
        conf.setDebug(true);
        conf.setNumWorkers(2);
        LocalCluster localCluster = new LocalCluster();
        localCluster.submitTopology("slidingwindow", conf, builder.createTopology());
    }
}

• 测试
  启动main方法，在命令行中连续输入字符串，就能看到滑动窗口计算结果。
  以上就是storm的滑动窗口演示。