Storm的WordCount案例（spout bolt详细总结）

男娘i 2022-12-23 07:24 86阅读 0赞

### spout介绍 ###

一个spout是由流组成的数据源在storm的拓扑里，通常情况下会读取外部的数据源   
然后emit（发射）到拓扑里面，比如是kafka，MySQL或者redis等等，Spout有两种实现一种是可靠的消息实现，如果发送失败则会重试，另外一种是不可靠的消息实现可能会出现消息丢失，spout可以一次声明多个数据流通过OutputFieldsDeclarer类的declareStream方法，当然前提是你的SpoutOutputCollector里的emit也是多个流

Spout里面主要的方法是nextTuple，它里面可以发射新的tuple到拓扑，或者当没有消息的时候就return，需要注意，这个方法里面不能阻塞，因为storm调用spout方法是单线程的，其他的主要方法是ack和fail，如果使用了可靠的spout，可以使用ack和fail来确定消息发送状态

相关扩展：   
IRichSpout：spout类必须实现的接口   
BaseRichSpout ：可靠的spout有ack确保   
BaseBasicSpout ：不可靠的spout

## 1.Spout组件：**创建Spout****（WordCountSpout****）组件采集数据，作为整个Topology****的数据源** ##

WordCountSpout：

package storm;
    
    import lombok.SneakyThrows;
    import org.apache.storm.spout.SpoutOutputCollector;
    import org.apache.storm.task.TopologyContext;
    import org.apache.storm.topology.IRichSpout;
    import org.apache.storm.topology.OutputFieldsDeclarer;
    import org.apache.storm.tuple.Fields;
    import org.apache.storm.tuple.Values;
    
    import java.util.Map;
    import java.util.Random;
    import java.util.concurrent.TimeUnit;
    
    /**
     * @author: wtl
     * @License: (C) Copyright 2020, wtl Corporation Limited.
     * @Contact: 1050100468@qq.com
     * @Date: 2020/11/27 5:14
     * @Version: 1.0
     * @Description:
     */
    public class WordCountSpout implements IRichSpout {
    
        private SpoutOutputCollector spoutOutputCollector;
        private String [] lines = {"I love you","hello world","hello kitty","nihao beijing"};
        private Random random = new Random();
    
        @Override
        public void open(Map<String, Object> map, TopologyContext topologyContext, SpoutOutputCollector spoutOutputCollector) {
            this.spoutOutputCollector = spoutOutputCollector;
        }
    
        @Override
        public void close() {
    
        }
    
        @Override
        public void activate() {
    
        }
    
        @Override
        public void deactivate() {
    
        }
    
        @SneakyThrows
        @Override
        public void nextTuple() {
            int nextInt = random.nextInt(lines.length);
            spoutOutputCollector.emit(new Values(lines[nextInt]));
            TimeUnit.SECONDS.sleep(1);
        }
    
        @Override
        public void ack(Object o) {
    
        }
    
        @Override
        public void fail(Object o) {
    
        }
    
        @Override
        public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) {
            outputFieldsDeclarer.declare(new Fields("line"));
        }
    
        @Override
        public Map<String, Object> getComponentConfiguration() {
            return null;
        }
    }

### bolt介绍 ###

Bolts 业务处理单元   
所有的拓扑处理都会在bolt中进行，bolt里面可以做任何etl，比如过滤，函数，聚合，连接，写入数据库系统或缓存等，一个bolt可以做简单的事件流转换，如果是复杂的流转化，往往需要多个bolt参与，这就是流计算，每个bolt都进行一个业务逻辑处理，bolt也可以emit多个流到下游，通过declareStream方法声明输出的schema。

Bolt里面主要的方法是execute方法，每次处理一个输入的tuple，bolt里面也可以发射新的tuple使用OutputCollector类，bolt里面每处理一个tuple必须调用ack方法以便于storm知道某个tuple何时处理完成。Strom里面的IBasicBolt接口可以自动   
调用ack。

相关拓展：   
IRichBolt：bolts的通用接口   
IBasicBolt：扩展的bolt接口，可以自动处理ack   
OutputCollector：bolt发射tuple到下游bolt里面

## 2.Bolt组件1：**创建Bolt****（WordCountSplitBolt****）组件进行分词操作** ##

SplitBolt：

package storm;
    
    import org.apache.storm.task.OutputCollector;
    import org.apache.storm.task.TopologyContext;
    import org.apache.storm.topology.IRichBolt;
    import org.apache.storm.topology.OutputFieldsDeclarer;
    import org.apache.storm.tuple.Fields;
    import org.apache.storm.tuple.Tuple;
    import org.apache.storm.tuple.Values;
    
    import java.util.Map;
    import java.util.stream.Stream;
    
    /**
     * @author: wtl
     * @License: (C) Copyright 2020, wtl Corporation Limited.
     * @Contact: 1050100468@qq.com
     * @Date: 2020/11/27 5:41
     * @Version: 1.0
     * @Description:
     */
    public class SplitBolt implements IRichBolt {
    
        private TopologyContext topologyContext;
        private OutputCollector outputCollector;
    
        @Override
        public void prepare(Map<String, Object> map, TopologyContext topologyContext, OutputCollector outputCollector) {
            this.topologyContext = topologyContext;
            this.outputCollector = outputCollector;
        }
    
        @Override
        public void execute(Tuple tuple) {
            String line = tuple.getStringByField("line");
            String[] splits = line.split(" ");
    
            Stream.of(splits).forEach(word -> {
                outputCollector.emit(new Values(word,1));
            });
        }
    
        @Override
        public void cleanup() {
    
        }
    
        @Override
        public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) {
            outputFieldsDeclarer.declare(new Fields("word","count"));
        }
    
        @Override
        public Map<String, Object> getComponentConfiguration() {
            return null;
        }
    }

## 3.Bolt组件2：**创建Bolt（WordCountTotalBolt）组件进行单词统计操作** ##

TotalBolt：

package storm;
    
    import org.apache.storm.task.OutputCollector;
    import org.apache.storm.task.TopologyContext;
    import org.apache.storm.topology.IRichBolt;
    import org.apache.storm.topology.OutputFieldsDeclarer;
    import org.apache.storm.tuple.Fields;
    import org.apache.storm.tuple.Tuple;
    import org.apache.storm.tuple.Values;
    
    import java.util.HashMap;
    import java.util.Map;
    
    /**
     * @author: wtl
     * @License: (C) Copyright 2020, wtl Corporation Limited.
     * @Contact: 1050100468@qq.com
     * @Date: 2020/11/27 5:57
     * @Version: 1.0
     * @Description:
     */
    public class TotalBolt implements IRichBolt {
        private TopologyContext topologyContext;
        private OutputCollector outputCollector;
        private Map<String,Integer> map;
    
        @Override
        public void prepare(Map<String, Object> map, TopologyContext topologyContext, OutputCollector outputCollector) {
            this.topologyContext = topologyContext;
            this.outputCollector = outputCollector;
            this.map = new HashMap<>();
        }
    
        @Override
        public void execute(Tuple tuple) {
            String word = tuple.getStringByField("word");
            Integer count = tuple.getIntegerByField("count");
            if (!map.containsKey(word)){
                map.put(word,count);
            }
            else{
                map.put(word,map.get(word) + count);
            }
    
            map.forEach((key, value) -> {
                System.out.println(key + ": " + value);
            });
        }
    
        @Override
        public void cleanup() {
        }
    
        @Override
        public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) {
            outputFieldsDeclarer.declare(new Fields("word","total"));
        }
    
        @Override
        public Map<String, Object> getComponentConfiguration() {
            return null;
        }
    }

## **4.Topology主程序:** ##

WordCountTopology:

package storm;
    
    import org.apache.storm.Config;
    import org.apache.storm.LocalCluster;
    import org.apache.storm.generated.StormTopology;
    import org.apache.storm.topology.TopologyBuilder;
    import org.apache.storm.tuple.Fields;
    
    /**
     * @author: wtl
     * @License: (C) Copyright 2020, wtl Corporation Limited.
     * @Contact: 1050100468@qq.com
     * @Date: 2020/11/27 6:06
     * @Version: 1.0
     * @Description:
     */
    public class WordCountTopology {
        public static void main(String[] args) throws Exception {
            TopologyBuilder topologyBuilder = new TopologyBuilder();
    
            topologyBuilder.setSpout("wcSpout",new WordCountSpout(),1);
            topologyBuilder.setBolt("wcSplitBolt",new SplitBolt(),1).shuffleGrouping("wcSpout");
    
            topologyBuilder.setBolt("wcTotalBolt",new TotalBolt(),1).fieldsGrouping("wcSplitBolt",new Fields("word"));
    
            //创建任务
            StormTopology job = topologyBuilder.createTopology();
    
            Config config = new Config();
    
            //运行任务有两种模式
            //1 本地模式   2 集群模式
    
            //1、本地模式
            LocalCluster localCluster = new LocalCluster();
            localCluster.submitTopology("MyWordCount",config,job);
        }
    }