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asp.net-core - Kafka - 在 ASP.Net Core 中实例化生产者类时出错

问题描述

我在用Confluent.Kafka

string kafkaEndpoint = "127.0.0.1:9092";

        string kafkaTopic = "testtopic";

        var producerConfig = new Dictionary<string, object> { { "bootstrap.servers", kafkaEndpoint } };

        using (var producer = new Producer<Null, string>(producerConfig, null, new StringSerializer(Encoding.UTF8)))
        {
            // Send 10 messages to the topic
            for (int i = 0; i < 10; i++)
            {
                var message = $"Event {i}";
                var result = producer.ProduceAsync(kafkaTopic, null, message).GetAwaiter().GetResult();
                Console.WriteLine($"Event {i} sent on Partition: {result.Partition} with Offset: {result.Offset}");
            }
        }

我收到以下编译时错误：

Producer.ProduceAsync(TopicPartition, Message)' 由于其保护级别而无法访问

像这样使用ProducerBuilder：

var result = producer.ProduceAsync(kafkaTopic, new Message<Null, MyClass>{ Value = myObject}).GetAwaiter().GetResult();

显示错误：

Cannot convert from 'Confluent.Kafka.Message<Confluent.Kafka.Null, MyClass>' to 'Confluent.Kafka.Message<Confluent.Kafka.Null, string>

标签： asp.net-coreapache-kafkakafka-producer-apiapache-kafka-connect

解决方案

在Confluent.Kafkanuget v1.0.1 中，Producerclass 是一个内部类，即它不可访问。看起来您需要改为使用ProducerBuilder，例如：

var producerConfig = new Dictionary<string, string> { { "bootstrap.servers", kafkaEndpoint } };

using (var producer = new ProducerBuilder<Null, string>(producerConfig)
    .SetKeySerializer(Serializers.Null)
    .SetValueSerializer(Serializers.Utf8)
    .Build())
{
    // Send 10 messages to the topic
    for (int i = 0; i < 10; i++)
    {
        var message = $"Event {i}";
        var result = producer.ProduceAsync(kafkaTopic, new Message<Null, string>{ Value = message}).GetAwaiter().GetResult();
        Console.WriteLine($"Event {i} sent on Partition: {result.Partition} with Offset: {result.Offset}");
    }
}

看起来任意类的实例可以发送为（MyClass用目标类代替）：

        var result = producer.ProduceAsync(kafkaTopic, new Message<Null, MyClass>{ Value = myObject}).GetAwaiter().GetResult();

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