要解决“Apache Storm - 动态扩展的能力”包含代码示例的问题,可以按照以下步骤进行:
步骤1:安装 Apache Storm 首先,您需要安装 Apache Storm。您可以从 Apache Storm 的官方网站(https://storm.apache.org/downloads.html)下载最新的稳定版本并按照说明进行安装。
步骤2:创建一个拓扑 在 Apache Storm 中,一个拓扑(Topology)是由多个组件组成的数据处理流程。下面是一个简单的示例拓扑,其中包含一个 Spout(数据源)和一个 Bolt(数据处理器):
import org.apache.storm.Config;
import org.apache.storm.LocalCluster;
import org.apache.storm.topology.TopologyBuilder;
import org.apache.storm.tuple.Fields;
public class DynamicTopologyExample {
public static void main(String[] args) throws Exception {
// 创建一个TopologyBuilder
TopologyBuilder builder = new TopologyBuilder();
// 设置Spout
builder.setSpout("spout", new MySpout());
// 设置Bolt,并指定输入字段为"word",输出字段为"count"
builder.setBolt("bolt", new MyBolt())
.fieldsGrouping("spout", new Fields("word"));
// 创建一个配置对象
Config config = new Config();
config.setDebug(true);
// 在本地模式下运行拓扑
LocalCluster cluster = new LocalCluster();
cluster.submitTopology("dynamic-topology-example", config, builder.createTopology());
// 等待30秒
Thread.sleep(30000);
// 停止拓扑
cluster.killTopology("dynamic-topology-example");
// 关闭本地集群
cluster.shutdown();
}
}
步骤3:实现自定义的 Spout 和 Bolt 在上述代码中,我们创建了一个名为 MySpout 的自定义 Spout 和一个名为 MyBolt 的自定义 Bolt。您需要根据实际需求实现这些组件。
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;
import java.util.Map;
public class MySpout extends BaseRichSpout {
private SpoutOutputCollector collector;
private String[] words = {"Hello", "World", "Apache", "Storm"};
@Override
public void open(Map conf, TopologyContext context, SpoutOutputCollector collector) {
this.collector = collector;
}
@Override
public void nextTuple() {
for (String word : words) {
collector.emit(new Values(word));
}
}
@Override
public void declareOutputFields(OutputFieldsDeclarer declarer) {
declarer.declare(new Fields("word"));
}
}
import org.apache.storm.task.OutputCollector;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.base.BaseRichBolt;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;
import java.util.Map;
public class MyBolt extends BaseRichBolt {
private OutputCollector collector;
@Override
public void prepare(Map conf, TopologyContext context, OutputCollector collector) {
this.collector = collector;
}
@Override
public void execute(Tuple tuple) {
String word = tuple.getStringByField("word");
int count = word.length();
collector.emit(new Values(word, count));
collector.ack(tuple);
}
@Override
public void declareOutputFields(OutputFieldsDeclarer declarer) {
declarer.declare(new Fields("word", "count"));
}
}
步骤4:运行拓扑 完成上述步骤后,您可以使用 Maven 构建并运行拓扑:
$ mvn clean package
$ storm jar target/my-topology.jar com.example.DynamicTopologyExample
这将在本地模式下运行拓扑,它将不断地从 MySpout 中获取数据,并通过 My