storm自带例子详解 （四）——ManualDRPC

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package storm.starter;

import backtype.storm.Config;
import backtype.storm.LocalCluster;
import backtype.storm.LocalDRPC;
import backtype.storm.drpc.DRPCSpout;
import backtype.storm.drpc.ReturnResults;
import backtype.storm.topology.BasicOutputCollector;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.TopologyBuilder;
import backtype.storm.topology.base.BaseBasicBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;

/*
** 手工（手动的）的分布式RPC
*/
public class ManualDRPC {
// 定义一个Bolt，继承自BaseBasicBolt
public static class ExclamationBolt extends BaseBasicBolt {

// 定义输出字段
@Override
public void declareOutputFields(OutputFieldsDeclarer declarer) {
// 定义了两个输出字段，分别是：result、return-info
declarer.declare(new Fields("result", "return-info"));
}

// 执行函数
@Override
public void execute(Tuple tuple, BasicOutputCollector collector) {
// 接收第一个字段的数据
String arg = tuple.getString(0);
// 接收第二个字段的数据
Object retInfo = tuple.getValue(1);
// 发射数据
collector.emit(new Values(arg + "!!!", retInfo));
}

}

public static void main(String[] args) {
// 拓扑构建器
TopologyBuilder builder = new TopologyBuilder();
// 本地分布式RPC
LocalDRPC drpc = new LocalDRPC();

// 定义一个分布式RPC的Spout，名叫exclamation
DRPCSpout spout = new DRPCSpout("exclamation", drpc);

// 设置拓扑的Spout，名为drpc
builder.setSpout("drpc", spout);
// 设置拓扑的Bolt，名为exclaim，接收drpc的数据，并行度是3
builder.setBolt("exclaim", new ExclamationBolt(), 3).shuffleGrouping("drpc");
// 设置拓扑的Bolt，名为return，接收exclaim的数据，并行度是3
builder.setBolt("return", new ReturnResults(), 3).shuffleGrouping("exclaim");

// 创建本地集群
LocalCluster cluster = new LocalCluster();
Config conf = new Config();
// 提交拓扑，该拓扑被命名为exclaim
cluster.submitTopology("exclaim", conf, builder.createTopology());

// 分布式RPC操作相应的数据，或者说，分布式RPC发送数据给Spout（exclamation）
System.out.println(drpc.execute("exclamation", "aaa"));
System.out.println(drpc.execute("exclamation", "bbb"));

}
}