kafka环境搭建及demo

概述
文件下载
系统环境搭建和配置
kafka demo
参考
1. 概述
  - kafka是一个分布式的消息缓存系统
  - kafka集群中的服务器都叫做broker
  - kafka有两类客户端，一类叫producer（消息生产者），一类叫做consumer（消息消费者），客户端和broker服务器之间采用tcp协议连接
  - kafka中不同业务系统的消息可以通过topic进行区分，而且每一个消息topic都会被分区，以分担消息读写的负载
  - 每一个分区都可以有多个副本，以防止数据的丢失
  - 某一个分区中的数据如果需要更新，都必须通过该分区所有副本中的leader来更新
  - 消费者可以分组，比如有两个消费者组A和B，共同消费一个topic：order_info,A和B所消费的消息不会重复，比如 order_info 中有100个消息，每个消息有一个id,编号从0-99，那么，如果A组消费0-49号，B组就消费50-99号
  - 消费者在具体消费某个topic中的消息时，可以指定起始偏移量
2. 文件下载
  - zookeeper下载
    下载地址：http://apache.fayea.com/zookeeper/zookeeper-3.3.6/zookeeper-3.3.6.tar.gz
  - kafka下载
    地址：https://mirrors.tuna.tsinghua.edu.cn/apache/kafka/0.11.0.0/kafka_2.11-0.11.0.0.tgz
3. 系统环境搭建和配置
  - java7配置省略
  - zookeeper配置（此处略，参考：http://blog.csdn.net/lxf20054658/article/details/74452755）
  - kafka配置
  - 上传kafka_2.11-0.11.0.0.tgz到centos服务器
  - 解压，tar -zxvf kafka_2.11-0.11.0.0.tgz，mv kafka_2.11-0.11.0.0 /usr/lib/apache-kafka
  - 配置，cd /usr/lib/apache-kafka/config，vi server.properties，配置示例（参考颜色标注的地方即可）：

# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# see kafka.server.KafkaConfig for additional details and defaults

############################# Server Basics #############################

# The id of the broker. This must be set to a unique integer for each broker.
broker.id=1

# Switch to enable topic deletion or not, default value is false
#delete.topic.enable=true

############################# Socket Server Settings #############################

# The address the socket server listens on. It will get the value returned from
# java.net.InetAddress.getCanonicalHostName() if not configured.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092
#listeners=PLAINTEXT://:9092

# Hostname and port the broker will advertise to producers and consumers. If not set,
# it uses the value for "listeners" if configured.  Otherwise, it will use the value
# returned from java.net.InetAddress.getCanonicalHostName().
#advertised.listeners=PLAINTEXT://your.host.name:9092

# Maps listener names to security protocols, the default is for them to be the same. See the config documentation for more details
#listener.security.protocol.map=PLAINTEXT:PLAINTEXT,SSL:SSL,SASL_PLAINTEXT:SASL_PLAINTEXT,SASL_SSL:SASL_SSL

# The number of threads that the server uses for receiving requests from the network and sending responses to the network
num.network.threads=3

# The number of threads that the server uses for processing requests, which may include disk I/O
num.io.threads=8
# The send buffer (SO_SNDBUF) used by the socket server
socket.send.buffer.bytes=102400

# The receive buffer (SO_RCVBUF) used by the socket server
socket.receive.buffer.bytes=102400

# The maximum size of a request that the socket server will accept (protection against OOM)
socket.request.max.bytes=104857600


############################# Log Basics #############################

# A comma seperated list of directories under which to store log files
log.dirs=/tmp/kafka-logs

# The default number of log partitions per topic. More partitions allow greater
# parallelism for consumption, but this will also result in more files across
# the brokers.
num.partitions=1

# The number of threads per data directory to be used for log recovery at startup and flushing at shutdown.
# This value is recommended to be increased for installations with data dirs located in RAID array.
num.recovery.threads.per.data.dir=1

############################# Internal Topic Settings  #############################
# The replication factor for the group metadata internal topics "__consumer_offsets" and "__transaction_state"
# For anything other than development testing, a value greater than 1 is recommended for to ensure availability such as 3.
offsets.topic.replication.factor=1
transaction.state.log.replication.factor=1
transaction.state.log.min.isr=1

############################# Log Flush Policy #############################

# Messages are immediately written to the filesystem but by default we only fsync() to sync
# the OS cache lazily. The following configurations control the flush of data to disk.
# There are a few important trade-offs here:
#    1. Durability: Unflushed data may be lost if you are not using replication.
#    2. Latency: Very large flush intervals may lead to latency spikes when the flush does occur as there will be a lot of data to flush.
#    3. Throughput: The flush is generally the most expensive operation, and a small flush interval may lead to exceessive seeks.
# The settings below allow one to configure the flush policy to flush data after a period of time or
# every N messages (or both). This can be done globally and overridden on a per-topic basis.

# The number of messages to accept before forcing a flush of data to disk
#log.flush.interval.messages=10000

# The maximum amount of time a message can sit in a log before we force a flush
#log.flush.interval.ms=1000

############################# Log Retention Policy #############################

# The following configurations control the disposal of log segments. The policy can
# be set to delete segments after a period of time, or after a given size has accumulated.
# A segment will be deleted whenever *either* of these criteria are met. Deletion always happens
# from the end of the log.

# The minimum age of a log file to be eligible for deletion due to age
log.retention.hours=168

# A size-based retention policy for logs. Segments are pruned from the log as long as the remaining
# segments don't drop below log.retention.bytes. Functions independently of log.retention.hours.
#log.retention.bytes=1073741824

# The maximum size of a log segment file. When this size is reached a new log segment will be created.
log.segment.bytes=1073741824
# The interval at which log segments are checked to see if they can be deleted according
# to the retention policies
log.retention.check.interval.ms=300000

############################# Zookeeper #############################

# Zookeeper connection string (see zookeeper docs for details).
# This is a comma separated host:port pairs, each corresponding to a zk
# server. e.g. "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002".
# You can also append an optional chroot string to the urls to specify the
# root directory for all kafka znodes.
zookeeper.connect=hadooplearn:2181

# Timeout in ms for connecting to zookeeper
zookeeper.connection.timeout.ms=6000


############################# Group Coordinator Settings #############################

# The following configuration specifies the time, in milliseconds, that the GroupCoordinator will delay the initial consumer rebalance.
# The rebalance will be further delayed by the value of group.initial.rebalance.delay.ms as new members join the group, up to a maximum of max.poll.interval.ms.
# The default value for this is 3 seconds.
# We override this to 0 here as it makes for a better out-of-the-box experience for development and testing.
# However, in production environments the default value of 3 seconds is more suitable as this will help to avoid unnecessary, and potentially expensive, rebalances during application startup.
group.initial.rebalance.delay.ms=0

    * 启动broker

bin/kafka-server-start.sh config/server.properties

    * 在kafka集群中创建一个topic

bin/kafka-topics.sh –create –zookeeper hadooplearn:2181 –replication-factor 1 –partitions 1 –topic order

    * 查看topic

bin/kafka-topics.sh –list –zookeeper hadooplearn:2181

    * 用一个producer向某一个topic中写入消息（往话题order写消息）

bin/kafka-console-producer.sh –broker-list hadooplearn:9092 –topic order

    * 用一个comsumer从某一个topic中读取信息

bin/kafka-console-consumer.sh –zookeeper hadooplearn:2181 –from-beginning –topic order

    * 查看一个topic的分区及副本状态信息

bin/kafka-topics.sh –describe –zookeeper hadooplearn:2181 –topic order

1. kafka demo

注：基于kafka_2.11-0.11.0.0.tgz包
生产者：

package cn.itcast.kafka;
import java.util.Properties;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.Producer;
import org.apache.kafka.clients.producer.ProducerRecord;

/**
 * see http://kafka.apache.org/090/javadoc/index.html?org/apache/kafka/clients/producer/KafkaProducer.html 
 * @author xfli
 *
 */
public class ProducerDemo {
      /**
       * @param args
       */
      public static void main(String[] args) {
            Properties props = new Properties();
            props.put("bootstrap.servers", "hadooplearn:9092");
            props.put("metadata.broker.list","hadooplearn:9092");
            props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
            props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
            Producer<String, String> producer = new KafkaProducer<>(props);
            // 发送业务消息
            // 读取文件 读取内存数据库 读socket端口
            for (int i = 1; i <= 100; i++) {
                  try {
                        Thread.sleep(500);
                  } catch (InterruptedException e) {
                        e.printStackTrace();
                  }
                  producer.send(new ProducerRecord<String, String>("wordcount",
                              i+" said "+ i + " love you baby for " + i + " times,will you have a nice day with me tomorrow"));
            }
      }
}

消费者：

package cn.itcast.kafka;

import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.errors.WakeupException;

/**
 * see http://kafka.apache.org/090/javadoc/index.html?org/apache/kafka/clients/consumer/KafkaConsumer.html
 * consumer/KafkaConsumer.html
 *
 * @author xfli
 *
 */
public class ConsumerDemo implements Runnable {
      private final AtomicBoolean closed = new AtomicBoolean(false);
      KafkaConsumer<String, String> consumer;// = new KafkaConsumer<>(props);

      public void run() {
            try {
                  Properties props = new Properties();
                  props.put("bootstrap.servers", "hadooplearn:9092");
                  props.put("group.id", "test");
                  props.put("enable.auto.commit", "true");
                  props.put("auto.commit.interval.ms", "1000");
                  props.put("session.timeout.ms", "30000");
                  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("wordcount"));
                  while (!closed.get()) {
                        ConsumerRecords<String, String> records = consumer.poll(10000);
                        // Handle new records
                        for (final ConsumerRecord<String, String> rc : records) {
                              System.out.println("msg=" + rc.value());
                        }
                        try {
                              Thread.sleep(500);
                        } catch (InterruptedException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
                        }
                  }
            } catch (WakeupException e) {
                  // Ignore exception if closing
                  if (!closed.get())
                        throw e;
            } finally {
                  consumer.close();
            }
      }

      // Shutdown hook which can be called from a separate thread
      public void shutdown() {
            closed.set(true);
            consumer.wakeup();
      }

      /**
       * @param args
       */
      public static void main(String[] args) {
            // TODO Auto-generated method stub
            ConsumerDemo sub1 = new ConsumerDemo();
            Thread tsub1 = new Thread(sub1);
            tsub1.start();
      }

}

运行结果示例：

msg=56 said 56 love you baby for 56 times,will you have a nice day with me tomorrow
msg=57 said 57 love you baby for 57 times,will you have a nice day with me tomorrow
msg=58 said 58 love you baby for 58 times,will you have a nice day with me tomorrow
msg=59 said 59 love you baby for 59 times,will you have a nice day with me tomorrow
msg=60 said 60 love you baby for 60 times,will you have a nice day with me tomorrow
msg=61 said 61 love you baby for 61 times,will you have a nice day with me tomorrow
msg=62 said 62 love you baby for 62 times,will you have a nice day with me tomorrow
msg=63 said 63 love you baby for 63 times,will you have a nice day with me tomorrow
msg=64 said 64 love you baby for 64 times,will you have a nice day with me tomorrow
msg=65 said 65 love you baby for 65 times,will you have a nice day with me tomorrow

参考：
http://kafka.apache.org/090/javadoc/index.html?org/apache/kafka/clients/producer/KafkaProducer.html

http://kafka.apache.org/090/javadoc/index.html?org/apache/kafka/clients/consumer/KafkaConsumer.html

kafka环境搭建及demo

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