我在servlet上设置了一个kafka消费者。我阅读了kafka主题，并希望使用servlet的doget方法打印最新的值。
但是如果我把狗送回去我只会得到一个空的。。。
我不确定，但我发现另一个帖子，有人提到，这可能是因为没有连接到zookeeper服务器。所以我试着解决这个问题 zookeeper.connection 消费者的财产；即使已经过时了。
希望有人能给我一些建议。
我的servlet代码：
public class KafkaServlet extends HttpServlet implements Runnable {
public String kafkaMessage;
private Properties props;
private KafkaConsumer<String, String> consumer;
Thread Trans;
/**
* setting up the properties and other consumer using the constructor of KafkaServlet
* /
public KafkaServlet() {
props = new Properties();
props.put("bootstrap.servers", "localhost:9092"); //replace 'localhost' with the actual IP to get it working.
props.put("zookeeper.connect", "localhost:2181");
props.put("auto.offset.reset", "earliest");
props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
consumer = new KafkaConsumer<>(props);
consumer.subscribe(Arrays.asList("kafkaTopic"));
}
/**
* setup the thread and run it using the init-method
* /
@Override
public void init (ServletConfig config) throws ServletException {
super.init(config);
Trans = new Thread(this);
Trans.setPriority(Thread.MIN_PRIORITY);
Trans.start();
}
/**
* implement the doPost-Method if we want to use it
* /
public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
//empty -- nothing to post here
}
/**
* doGet will get print out our returned message from kafka
* /
@Override
public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
res.setContentType("text/html");
PrintWriter out = res.getWriter();
String title = "Reading Parameters from kafkaTopic";
out.println("<HTML>" +
"<BODY>\n" +
"<H1 ALIGN=CENTER>" + title + "</H1>\n" +
"<UL>\n" +
" <LI>MESSAGE: "
+ kafkaMessage + "\n" +
"</UL>\n" +
"</BODY></HTML>");
}
/**
* thread, which grabs the messages from kafka and stores the latest one in "kafkaMessage"
* /
@Override
public void run() {
try {
while (true) {
ConsumerRecords<String, String> records = consumer.poll(100);
for (ConsumerRecord<String, String> record : records) {
//KafkaMessage.setMessage(record.value());
kafkaMessage = record.value();
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
consumer.close();
}
}}编辑：“localhost.log”中的最新日志文件： 19-Dec-2016 13:42:42.773 INFO [localhost-startStop-2] org.apache.catalina.core.ApplicationContext.log SessionListener: contextDestroyed() 19-Dec-2016 13:42:42.774 INFO [localhost-startStop-2] org.apache.catalina.core.ApplicationContext.log ContextListener: contextDestroyed() 19-Dec-2016 13:42:54.742 INFO [localhost-startStop-1] org.apache.catalina.core.ApplicationContext.log ContextListener: contextInitialized() 19-Dec-2016 13:42:54.745 INFO [localhost-startStop-1] org.apache.catalina.core.ApplicationContext.log SessionListener: contextInitialized()
1条答案
按热度按时间igetnqfo1#
我想出来了：问题是，为什么我没有收到任何消息是线路
props.put("bootstrap.servers", "localhost:9092");.我不得不把“localhost”改成我虚拟机的实际ip地址。这有点奇怪，因为我配置的所有其他属性（在ApacheStorm上；Kafka；另一个servlet（包含一个kafka生产者）与“localhost”配合得很好。