Spring Kafka 模板 - 在 Spring Boot 启动时连接到 Kafka 主题

Question

我已经实现了一个使用 Spring Kafka 的基本 Spring Boot 应用程序。我希望我的制作人在第一个主题被调用之前连接到 Kafka 主题.send()，但我找不到方法来做到这一点。那可能吗？

日志显示 KafkaTemplate 仅在我触发以下.send方法后连接到 Kafka 主题16:12:44：

2021-11-24 16:12:12.602  INFO 63930 --- [           main] c.e.k.KafkaProducerExampleApplication    : The following profiles are active: dev
2021-11-24 16:12:13.551  INFO 63930 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2021-11-24 16:12:13.559  INFO 63930 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-11-24 16:12:13.559  INFO 63930 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.53]
2021-11-24 16:12:13.613  INFO 63930 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2021-11-24 16:12:13.613  INFO 63930 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 974 ms
2021-11-24 16:12:13.989  INFO 63930 --- [           main] pertySourcedRequestMappingHandlerMapping : Mapped URL path [/v2/api-docs] onto method [springfox.documentation.swagger2.web.Swagger2Controller#getDocumentation(String, HttpServletRequest)]
2021-11-24 16:12:14.190  INFO 63930 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2021-11-24 16:12:14.190  INFO 63930 --- [           main] d.s.w.p.DocumentationPluginsBootstrapper : Context refreshed
2021-11-24 16:12:14.207  INFO 63930 --- [           main] d.s.w.p.DocumentationPluginsBootstrapper : Found 1 custom documentation plugin(s)
2021-11-24 16:12:14.239  INFO 63930 --- [           main] s.d.s.w.s.ApiListingReferenceScanner     : Scanning for api listing references
2021-11-24 16:12:14.336  INFO 63930 --- [           main] c.e.k.KafkaProducerExampleApplication    : Started KafkaProducerExampleApplication in 7.055 seconds (JVM running for 7.341)
2021-11-24 16:12:44.550  INFO 63930 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-11-24 16:12:44.550  INFO 63930 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2021-11-24 16:12:44.551  INFO 63930 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 1 ms
2021-11-24 16:12:44.649  INFO 63930 --- [nio-8080-exec-1] o.a.k.clients.producer.ProducerConfig    : ProducerConfig values: 

Answer 1

关于 Linh Vu 的答案，最好不要在 bean 定义中创建连接 - 这在应用程序上下文的生命周期中还为时过早。

SmartLifecycle相反，添加一个实现并创建连接的bean start()；这样，上下文将在连接之前完全初始化。

@Bean
SmartLifecycle connector(ProducerFactory<Object ,Object> pf) {
    return new SmartLifecycle() {
        
        @Override
        public void stop() {
        }
        
        @Override
        public void start() {
            pf.createProducer().close();
        }
        
        @Override
        public boolean isRunning() {
            return false;
        }
        
    };
}