storm Trident编程之Function

Trident编程实质与普通的storm源码API编程没有什么本质，其只是对topology出的逻辑执行代码进行了封装，使得编码处理更一体化，功能类要继承BaseFunction类，重写execute一个方法，不在想原始API编程那样重写很多方法，造成代码冗余。
直接上代码

/**
 * 
 * @author mis
 *
 * Trident的作用就是简化了bolt
 */
public class TridentFunction {
    
    public static class SumFunction extends BaseFunction {

        public void execute(TridentTuple tuple, TridentCollector collector) {
            System.out.println("传入进来的内容为：" + tuple);
            //获取a、b两个域值
            int a = tuple.getInteger(0);//第0个元素
            int b = tuple.getInteger(1);//第1个元素
            int sum = a + b ; //sum计算前两个元素之和
            //发射数据
            collector.emit(new Values(sum));
        }   
    }
    
    public static class Result extends BaseFunction {

        @Override
        public void execute(TridentTuple tuple, TridentCollector collector) {
            //获取tuple输入内容
            Integer a = tuple.getIntegerByField("a");
            Integer b = tuple.getIntegerByField("b");
            Integer c = tuple.getIntegerByField("c");
            Integer d = tuple.getIntegerByField("d");
            Integer sum = tuple.getIntegerByField("sum");
            System.out.println("a: " + a +", b: " + b + ", c: " + c + ", d: " +d + ", sum: " + sum);
        }   
    }

    public static StormTopology buildTopology() {
        TridentTopology topology = new TridentTopology();
        //设定数据源
        @SuppressWarnings("unchecked")
        FixedBatchSpout spout = new FixedBatchSpout(
                new Fields("a","b","c","d"),//声明输入的域字段为"a","b","c","d"
                4,//设置批处理大小
                
                //设置数据源内容（此处测试数据）
                new Values(1,4,7,10),
                new Values(1,1,3,11),
                new Values(2,2,7,1),
                new Values(2,5,7,2));
        
        //指定是否循环
        spout.setCycle(false);
        //指定输入员
        Stream inputStream = topology.newStream("spout", spout);
        /**
         * 要实现流spout - bolt的模式 在trident里是使用each来做到的
         * each方法参数：
         *      1,输入数据源参数名称："a","b","c","d"
         *      2,需要流转执行的function对象（也就是bolt对象）：new SumFunction()
         *      3,指定function对象里的输出参数名称：sum
         * */
        inputStream.each(new Fields("a","b","c","d"), new SumFunction(),new Fields("sum"))
                /**
                 * 继续使用each调用下一个function（bolt）
                 *      1,参数一为："a","b","c","d","sum"
                 *      2,参数二为：new Result() 也就是执行函数，第三个参数为没有输出（即这是最后一个bolt）
                 * */
                .each(new Fields("a","b","c","d","sum"),new Result(),new Fields());
        
        return topology.build();//利用这种方式，我们返回一个StormTopology对象，进行提交
    }
    
    
    
    public static void main(String[] args) throws Exception {
        Config conf = new Config();
        conf.setNumWorkers(2);
        conf.setMaxSpoutPending(20);
        if(args.length == 0){//本地模式运行
            LocalCluster cluster = new LocalCluster();
            cluster.submitTopology("trident-function", conf, buildTopology());
            Thread.sleep(10000);
            cluster.shutdown();
        }else{//集群模式运行
            StormSubmitter.submitTopology(args[0], conf, buildTopology());
        }
    }
}

使用each()方法进行链式编程，数据所流向的bolt类直接以对象的形式传入

结果：

2017-04-26_113201.png