[英]How to fix the error java.net.UnknownHostException while using Spring Boot and Eureka Server?
I have a Spring Boot microservice called "documents-microservice", which is registered in Eureka Server.我有一个名为“documents-microservice”的 Spring Boot 微服务,它在 Eureka Server 中注册。 I am trying to access this microservice using its name in the URL and with RestTemplate
, as the following:我正在尝试使用 URL 中的名称和RestTemplate
访问此微服务,如下所示:
ResponseEntity<String> response = restTemplate.exchange("http://documents-microservice/document-name", HttpMethod.POST, entity, String.class);
Although I am sure that the service name is available on Eureka Server which is running on port 8761 (See picture below), I still get the following errors:尽管我确定在端口 8761 上运行的 Eureka Server 上可以使用该服务名称(见下图),但我仍然收到以下错误:
Errors:错误:
org.springframework.web.client.ResourceAccessException: I/O error on POST request for "http://documents-microservice/document-name": documents-microservice; nested exception is java.net.UnknownHostException: documents-microservice
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:674)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:621)
at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:539)
at ae.gov.adm.saeed.web.controller.util.CircularsControllerUtil.circularListView(CircularsControllerUtil.java:196)
at ae.gov.adm.saeed.web.controller.CircularsController.viewCircularList(CircularsController.java:58)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at ae.gov.adm.saeed.web.security.AuthFilter.doFilter(AuthFilter.java:335)
at ae.gov.adm.saeed.web.security.AuthFilter.doFilter(AuthFilter.java:610)
at ae.gov.adm.common.web.filter.AbstractFilter.doFilter(AbstractFilter.java:47)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:417)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1376)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.UnknownHostException: documents-microservice
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at java.net.Socket.connect(Socket.java:538)
at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:463)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:558)
at sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
at sun.net.www.http.HttpClient.New(HttpClient.java:339)
at sun.net.www.http.HttpClient.New(HttpClient.java:357)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1220)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1156)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1050)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:984)
at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:78)
at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:660)
... 52 more
I/O error on POST request for "http://documents-microservice/document-name": documents-microservice; nested exception is java.net.UnknownHostException: documents-microservice
Update: Please note that I have the following method in the client for setting RestTemplate:更新:请注意,我在客户端有以下设置 RestTemplate 的方法:
@Bean //this methods will be executed only once to avoid getting multiple instances.
@LoadBalanced //I will not give you service URL, but rather a hint for what you need to discover.
public RestTemplate getRestTemplate()
{
final RestTemplate restTemplate = new RestTemplate();
System.out.println("rest template defined");
return restTemplate;
}
Update: Please note that currently, my client code is not a Spring Boot Application.更新:请注意,目前,我的客户端代码不是 Spring Boot 应用程序。
There are several things that you need to do:您需要做几件事:
@Configuration
public class WebClientConfiguration {
@Bean @LoadBalanced
public RestTemplate getRestTemplate() {
return new RestTemplate();
}
}
second: you need the corresponding dependencies in the pom.xml of the same service(1)第二:需要同服务的pom.xml中对应的依赖(1)
third: add @EnableDiscoveryClient
in your main application第三:在你的主应用程序中添加@EnableDiscoveryClient
And other configurations , but you must provide a full example to help you more.和其他配置一样,但是你必须提供一个完整的例子来帮助你更多。
This example can help you这个例子可以帮助你
You can access it by name "documents-microservice" via a @Feign client, otherwise you should try the gateway EG, hqtpm001....:8081您可以通过@Feign 客户端按名称“documents-microservice”访问它,否则您应该尝试网关 EG,hqtpm001....:8081
Furthermore, Eureka server is not the host of the application, it is more or less the traffic cop and lets you as the client know where to go to get the application.此外,Eureka 服务器不是应用程序的主机,它或多或少是交通警察,让您作为客户端知道去哪里获取应用程序。 aka the Service Registry又名服务注册中心
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