基于Confluent.Kafka实现的KafkaConsumer消费者类和KafkaProducer消息生产者类型

一、引言

　　研究Kafka有一段时间了，略有心得，基于此自己就写了一个Kafka的消费者的类和Kafka消息生产者的类，进行了单元测试和生产环境的测试，还是挺可靠的。

二、源码

　　话不多说，直接上代码，代码不是很难，注释很全，希望大家多多发表意见，继续提升。

     /// <summary>
     /// Kafka消息消费者接口
     /// </summary>
     public interface IKafkaConsumer
     {
         /// <summary>
         /// 指定的组别的消费者开始消费指定主题的消息
         /// </summary>
         /// <param name="broker">Kafka消息服务器的地址</param>
         /// <param name="topic">Kafka消息所属的主题</param>
         /// <param name="groupID">Kafka消费者所属的组别</param>
         /// <param name="action">可以对已经消费的消息进行相关处理</param>
         void Consume(string broker, string topic, string groupID, Action<ConsumerResult> action = null);
     }

　　以上类型是接口定义，这个类定义的抽象类，可以重复使用相关的代码定义其中，但是目前这两个方法没有使用。

     /// <summary>
     /// Kafka抽象基类，提供公共接口实现
     /// </summary>
     public abstract class KafkaBase
     {
         /// <summary>
         /// 获取Kafka服务器地址
         /// </summary>
         /// <param name="brokerNameKey">配置文件中Broker服务器地址的key的名称</param>
         /// <returns>返回获取到的Kafka服务器的地址明细</returns>
         public string GetKafkaBroker(string brokerNameKey = "Broker")
         {
             string kafkaBroker = string.Empty;            

             if (!ConfigurationManager.AppSettings.AllKeys.Contains(brokerNameKey))
             {
                 kafkaBroker = "http://localhost:9092";
             }
             else
             {
                 kafkaBroker = ConfigurationManager.AppSettings[brokerNameKey];
             }
             return kafkaBroker;
         }

         /// <summary>
         /// 在配置文件中获取系统中已经生成的主题名称
         /// </summary>
         /// <param name="topicNameKey">配置文件中主题的key名称</param>
         /// <returns>返回获取到的主题的具体值</returns>
         public string GetTopicName(string topicNameKey = "Topic")
         {
             string topicName = string.Empty;

             if (!ConfigurationManager.AppSettings.AllKeys.Contains(topicNameKey))
             {
                 throw new Exception("Key \"" + topicNameKey + "\" not found in Config file -> configuration/AppSettings");
             }
             else
             {
                 topicName = ConfigurationManager.AppSettings[topicNameKey];
             }
             return topicName;
         }
     }

　　还有一个用于数据传递的工具类，代码如下：

     /// <summary>
     /// Kafka消息消费者设置对象，提供Kafka消费消息的参数对象（Consumer.Consum）
     /// </summary>
     public sealed class ConsumerSetting
     {
         /// <summary>
         /// Kafka消息服务器的地址
         /// </summary>
         public string Broker { get; set; }

         /// <summary>
         /// Kafka消息所属的主题
         /// </summary>
         public string Topic { get; set; }

         /// <summary>
         /// Kafka消息消费者分组主键
         /// </summary>
         public string GroupID { get; set; }

         /// <summary>
         /// 消费消息后可以执行的方法
         /// </summary>
         public Action<ConsumerResult> Action { get; set; }
     }

　　我们可以对消息进行消费，该类型用于对消息进行整理，代码如下：

     /// <summary>
     /// 已经消费的消息的详情信息
     /// </summary>
     public sealed class ConsumerResult
     {
         /// <summary>
         /// Kafka消息服务器的地址
         /// </summary>
         public string Broker { get; set; }

         /// <summary>
         /// Kafka消息所属的主题
         /// </summary>
         public string Topic { get; set; }

         /// <summary>
         /// Kafka消息消费者分组主键
         /// </summary>
         public string GroupID { get; set; }

         /// <summary>
         /// 我们需要处理的消息具体的内容
         /// </summary>
         public string Message { get; set; }

         /// <summary>
         /// Kafka数据读取的当前位置
         /// </summary>
         public long Offset { get; set; }

         /// <summary>
         /// 消息所在的物理分区
         /// </summary>
         public int Partition { get; set; }
     }

　　最后阶段了，该是消费者的代码了，代码如下：

     /// <summary>
     /// Kafka消息消费者
     /// </summary>
     public sealed class KafkaConsumer : KafkaBase, IKafkaConsumer
     {
         #region 私有字段

         private bool isCancelled;

         #endregion

         #region 构造函数

         /// <summary>
         /// 构造函数，初始化IsCancelled属性
         /// </summary>
         public KafkaConsumer()
         {
             isCancelled = false;
         }

         #endregion

         #region 属性

         /// <summary>
         /// 是否应该取消继续消费Kafka的消息，默认值是false，继续消费消息
         /// </summary>
         public bool IsCancelled
         {
             get { return isCancelled; }
             set { isCancelled = value; }
         }

         #endregion

         #region 同步版本

         /// <summary>
         /// 指定的组别的消费者开始消费指定主题的消息
         /// </summary>
         /// <param name="broker">Kafka消息服务器的地址</param>
         /// <param name="topic">Kafka消息所属的主题</param>
         /// <param name="groupID">Kafka消费者所属的组别</param>
         /// <param name="action">可以对已经消费的消息进行相关处理</param>
         public void Consume(string broker, string topic, string groupID, Action<ConsumerResult> action = null)
         {
             if (string.IsNullOrEmpty(broker) || string.IsNullOrWhiteSpace(broker) || broker.Length <= )
             {
                 throw new ArgumentNullException("Kafka消息服务器的地址不能为空！");
             }

             if (string.IsNullOrEmpty(topic) || string.IsNullOrWhiteSpace(topic) || topic.Length <= )
             {
                 throw new ArgumentNullException("消息所属的主题不能为空！");
             }

             if (string.IsNullOrEmpty(groupID) || string.IsNullOrWhiteSpace(groupID) || groupID.Length <= )
             {
                 throw new ArgumentNullException("用户分组ID不能为空！");
             }

             var config = new Dictionary<string, object>
                 {
                     { "bootstrap.servers", broker },
                     { "group.id", groupID },
                     { "enable.auto.commit", true },  // this is the default
                     { "auto.commit.interval.ms",  },
                     { "statistics.interval.ms",  },
                     { "session.timeout.ms",  },
                     { "auto.offset.reset", "smallest" }
                 };

             using (var consumer = new Consumer<Ignore, string>(config, null, new StringDeserializer(Encoding.UTF8)))
             {
                 // Note: All event handlers are called on the main thread.
                 //consumer.OnMessage += (_, message) => Console.WriteLine("Topic：" + message.Topic + " Partition：" + message.Partition + " Offset：" + message.Offset + " " + message.Value);
                 //consumer.OnMessage += (_, message) => Console.WriteLine("Offset：【" + message.Offset + "】Message：【" + message.Value + "】");
                 if (action != null)
                 {
                     consumer.OnMessage += (_, message) => {
                         ConsumerResult messageResult = new ConsumerResult();
                         messageResult.Broker = broker;
                         messageResult.Topic = message.Topic;
                         messageResult.Partition = message.Partition;
                         messageResult.Offset = message.Offset.Value;
                         messageResult.Message = message.Value;

                         //执行外界自定义的方法
                         action(messageResult);
                     };
                 }

                 consumer.OnPartitionEOF += (_, end) => Console.WriteLine("Reached end of topic " + end.Topic + " partition " + end.Partition + ", next message will be at offset " + end.Offset);

                 consumer.OnError += (_, error) => Console.WriteLine("Error：" + error);

                 //引发反序列化错误或消费消息出现错误！= NoError。
                 consumer.OnConsumeError += (_, message) => Console.WriteLine("Error consuming from topic/partition/offset " + message.Topic + "/" + message.Partition + "/" + message.Offset + ": " + message.Error);

                 consumer.OnOffsetsCommitted += (_, commit) => Console.WriteLine(commit.Error ? "Failed to commit offsets：" + commit.Error : "Successfully committed offsets：" + commit.Offsets);

                 // 当消费者被分配一组新的分区时引发。
                 consumer.OnPartitionsAssigned += (_, partitions) =>
                 {
                     Console.WriteLine("Assigned Partitions：" + partitions + ", Member ID：" + consumer.MemberId);
                     //如果您未向OnPartitionsAssigned事件添加处理程序，则会自动执行以下.Assign调用。 如果你为它添加了事件处理程序，你必须明确地调用.Assign以便消费者开始消费消息。
                     consumer.Assign(partitions);
                 };

                 // Raised when the consumer's current assignment set has been revoked.
                 //当消费者的当前任务集已被撤销时引发。
                 consumer.OnPartitionsRevoked += (_, partitions) =>
                 {
                     Console.WriteLine("Revoked Partitions：" + partitions);
                     // If you don't add a handler to the OnPartitionsRevoked event,the below .Unassign call happens automatically. If you do, you must call .Unassign explicitly in order for the consumer to stop consuming messages from it's previously assigned partitions.
                     //如果您未向OnPartitionsRevoked事件添加处理程序，则下面的.Unassign调用会自动发生。 如果你为它增加了事件处理程序，你必须明确地调用.Usessign以便消费者停止从它先前分配的分区中消费消息。
                     consumer.Unassign();
                 };

                 //consumer.OnStatistics += (_, json) => Console.WriteLine("Statistics: " + json);

                 consumer.Subscribe(topic);

                 //Console.WriteLine("Subscribed to:" + consumer.Subscription);

                 while (!IsCancelled)
                 {
                     consumer.Poll(TimeSpan.FromMilliseconds());
                 }
             }
         }

         #endregion

         #region 异步版本

         /// <summary>
         /// 指定的组别的消费者开始消费指定主题的消息
         /// </summary>
         /// <param name="broker">Kafka消息服务器的地址</param>
         /// <param name="topic">Kafka消息所属的主题</param>
         /// <param name="groupID">Kafka消费者所属的组别</param>
         /// <param name="action">可以对已经消费的消息进行相关处理</param>
         public void ConsumeAsync(string broker, string topic, string groupID, Action<ConsumerResult> action = null)
         {
             if (string.IsNullOrEmpty(broker) || string.IsNullOrWhiteSpace(broker) || broker.Length <= )
             {
                 throw new ArgumentNullException("Kafka消息服务器的地址不能为空！");
             }

             if (string.IsNullOrEmpty(topic) || string.IsNullOrWhiteSpace(topic) || topic.Length <= )
             {
                 throw new ArgumentNullException("消息所属的主题不能为空！");
             }

             if (string.IsNullOrEmpty(groupID) || string.IsNullOrWhiteSpace(groupID) || groupID.Length <= )
             {
                 throw new ArgumentNullException("用户分组ID不能为空！");
             }

             ThreadPool.QueueUserWorkItem(KafkaAutoCommittedOffsets, new ConsumerSetting() { Broker = broker, Topic = topic, GroupID = groupID, Action=action });
         }

         #endregion

         #region 两种提交Offsets的版本

         /// <summary>
         /// Kafka消息队列服务器自动提交offset
         /// </summary>
         /// <param name="state">消息消费者信息</param>
         private void KafkaAutoCommittedOffsets(object state)
         {
             ConsumerSetting setting = state as ConsumerSetting;

             var config = new Dictionary<string, object>
                 {
                     { "bootstrap.servers", setting.Broker },
                     { "group.id", setting.GroupID },
                     { "enable.auto.commit", true },  // this is the default
                     { "auto.commit.interval.ms",  },
                     { "statistics.interval.ms",  },
                     { "session.timeout.ms",  },
                     { "auto.offset.reset", "smallest" }
                 };

             using (var consumer = new Consumer<Ignore, string>(config, null, new StringDeserializer(Encoding.UTF8)))
             {
                 if (setting.Action != null)
                 {
                     consumer.OnMessage += (_, message) =>
                     {
                         ConsumerResult messageResult = new ConsumerResult();
                         messageResult.Broker = setting.Broker;
                         messageResult.Topic = message.Topic;
                         messageResult.Partition = message.Partition;
                         messageResult.Offset = message.Offset.Value;
                         messageResult.Message = message.Value;

                         //执行外界自定义的方法
                         setting.Action(messageResult);
                     };
                 }

                 //consumer.OnStatistics += (_, json)=> Console.WriteLine("Statistics: {json}");

                 //可以写日志
                 //consumer.OnError += (_, error)=> Console.WriteLine("Error："+error);

                 //可以写日志
                 //consumer.OnConsumeError += (_, msg) => Console.WriteLine("Error consuming from topic/partition/offset {msg.Topic}/{msg.Partition}/{msg.Offset}: {msg.Error}");

                 consumer.Subscribe(setting.Topic);

                 while (!IsCancelled)
                 {
                     consumer.Poll(TimeSpan.FromMilliseconds());
                 }
             }
         }

         /// <summary>
         /// Kafka消息队列服务器手动提交offset
         /// </summary>
         /// <param name="state">消息消费者信息</param>
         private void  KafkaManuallyCommittedOffsets(object state)
         {
             ConsumerSetting setting = state as ConsumerSetting;

             var config = new Dictionary<string, object>
                 {
                     { "bootstrap.servers", setting.Broker },
                     { "group.id", setting.GroupID },
                     { "enable.auto.commit", false },//不是自动提交的
                     { "auto.commit.interval.ms",  },
                     { "statistics.interval.ms",  },
                     { "session.timeout.ms",  },
                     { "auto.offset.reset", "smallest" }
                 };

             using (var consumer = new Consumer<Ignore, string>(config, null, new StringDeserializer(Encoding.UTF8)))
             {
                 //可以写日志
                 //consumer.OnError += (_, error) => Console.WriteLine("Error："+error);

                 //可以写日志
                 // Raised on deserialization errors or when a consumed message has an error != NoError.
                 //consumer.OnConsumeError += (_, error)=> Console.WriteLine("Consume error："+error);

                 consumer.Subscribe(setting.Topic);

                 Message<Ignore, string> message = null;

                 while (!isCancelled)
                 {
                     if (!consumer.Consume(out message, TimeSpan.FromMilliseconds()))
                     {
                         continue;
                     }

                     if (setting.Action != null)
                     {
                         ConsumerResult messageResult = new ConsumerResult();
                         messageResult.Broker = setting.Broker;
                         messageResult.Topic = message.Topic;
                         messageResult.Partition = message.Partition;
                         messageResult.Offset = message.Offset.Value;
                         messageResult.Message = message.Value;

                         //执行外界自定义的方法
                         setting.Action(messageResult);
                     }

                     if (message.Offset %  == )
                     {
                         var committedOffsets = consumer.CommitAsync(message).Result;
                         //Console.WriteLine("Committed offset："+committedOffsets);
                     }
                 }
             }
         }

         #endregion
     }

　　有了消息的消费者代码，那消息的生产者代码肯定是少不了的。代码如下：

     /// <summary>
     /// Kafka消息生产者
     /// </summary>
     public sealed class KafkaProducer : KafkaBase, IKafkaProducer
     {
         /// <summary>
         /// 生产消息并发送消息
         /// </summary>
         /// <param name="broker">kafka的服务器地址</param>
         /// <param name="topic">kafka的消息主题名称</param>
         /// <param name="message">需要传送的消息</param>
         public bool Produce(string broker, string topic, string message)
         {
             bool result = false;
             if (string.IsNullOrEmpty(broker) || string.IsNullOrWhiteSpace(broker) || broker.Length <= )
             {
                 throw new ArgumentNullException("Kafka消息服务器地址不能为空！");
             }

             if (string.IsNullOrEmpty(topic) || string.IsNullOrWhiteSpace(topic) || topic.Length <= )
             {
                 throw new ArgumentNullException("消息所属的主题不能为空！");
             }

             if (string.IsNullOrEmpty(message) || string.IsNullOrWhiteSpace(message) || message.Length <= )
             {
                 throw new ArgumentNullException("消息内容不能为空！");
             }

             var config = new Dictionary<string, object> { { "bootstrap.servers", broker } };
             using (var producer = new Producer<Null, string>(config, null, new StringSerializer(Encoding.UTF8)))
             {
                 var deliveryReport = producer.ProduceAsync(topic, null, message);
                 deliveryReport.ContinueWith(task =>
                 {
                     if (task.Result.Error.Code == ErrorCode.NoError)
                     {
                         result = true;
                     }
                     //可以在控制台使用以下语句
                     //Console.WriteLine("Producer：" + producer.Name + "\r\nTopic：" + topic + "\r\nPartition：" + task.Result.Partition + "\r\nOffset：" + task.Result.Offset + "\r\nMessage：" + task.Result.Value);
                 });

                 producer.Flush(TimeSpan.FromSeconds());
             }
             return result;
         }
     }

　　好了，以上就是全部代码，大家可以整理使用。

三、总结

　　继续学习，先使用，慢慢了解内部的细节，我已经迈出了第一步，不忘初心，继续努力。