关于spring cloud eureka整合ribbon实现客户端的负载均衡

1. 实现eureka整合ribbon非常简单,

1.1.首先引入所需maven依赖

1 <dependency>
2     <groupId>org.springframework.boot</groupId>
3     <artifactId>spring-cloud-starter-ribbon</artifactId>
4 </dependency>

1.2.在创建RestTemplate的Bean时加上@LoadBalanced注解

1 @Bean
2 @LoadBalanced　　// 为restTemplate
3 public RestTemplate restTemplate() {
4     return new RestTemplate();
5 }

1.3.在注入RestTemplate时加上@LoadBalanced注解

1 @Autowired
2 @LoadBalanced
3 private RestTemplate restTemplate;

　　这里要注意几点:

　　　　1.3.1.在注入RestTemplate时, 一定要加上@LoadBalanced注解,

　　　　1.3.2.在eureka整合了ribbon之后, 使用RestTemplate时, 第一个参数URL必须是服务生产者的spring.application.name:的值, 也就是服务生产者的serviceId

　　否则会报java.lang.IllegalStateException: No instances available for ********异常,如下:

 1 java.lang.IllegalStateException: No instances available for 127.0.0.1
 2     at org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient.execute(RibbonLoadBalancerClient.java:75) ~[spring-cloud-netflix-core-1.3.1.RELEASE.jar:1.3.1.RELEASE]
 3     at org.springframework.cloud.client.loadbalancer.LoadBalancerInterceptor.intercept(LoadBalancerInterceptor.java:55) ~[spring-cloud-commons-1.2.2.RELEASE.jar:1.2.2.RELEASE]
 4     at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:86) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
 5     at org.springframework.cloud.netflix.metrics.MetricsClientHttpRequestInterceptor.intercept(MetricsClientHttpRequestInterceptor.java:64) ~[spring-cloud-netflix-core-1.3.1.RELEASE.jar:1.3.1.RELEASE]
 6     at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:86) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
 7     at org.springframework.http.client.InterceptingClientHttpRequest.executeInternal(InterceptingClientHttpRequest.java:70) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
 8     at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
 9     at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
10     at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:659) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
11     at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:620) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
12     at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:294) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
13     at org.springframework.web.client.RestTemplate$$FastClassBySpringCGLIB$$aa4e9ed0.invoke(<generated>) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
14     at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
15     at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
16     at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
17     at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:85) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
18     at org.springframework.cloud.netflix.metrics.RestTemplateUrlTemplateCapturingAspect.captureUrlTemplate(RestTemplateUrlTemplateCapturingAspect.java:33) ~[spring-cloud-netflix-core-1.3.1.RELEASE.jar:1.3.1.RELEASE]
19     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
20     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
21     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
22     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
23     at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:629) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
24     at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:618) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
25     at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
26     at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
27     at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
28     at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
29     at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673) ~[spring-aop-4.3.13.RELEASE.jar:4.3.13.RELEASE]
30     at org.springframework.web.client.RestTemplate$$EnhancerBySpringCGLIB$$b2d47b63.getForObject(<generated>) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
31     at com.iot.dywl.demo.spring.cloud.eureka.movie.controller.MovieController.findUserByIdRestTemplate(MovieController.java:46) ~[classes/:na]
32     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
33     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
34     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
35     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
36     at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
37     at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
38     at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
39     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
40     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
41     at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
42     at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
43     at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
44     at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
45     at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
46     at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
47     at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
48     at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
49     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
50     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
51     at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.23.jar:8.5.23]
52     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
53     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
54     at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55) ~[spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
55     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
56     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
57     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
58     at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:110) ~[spring-boot-actuator-1.5.9.RELEASE.jar:1.5.9.RELEASE]
59     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
60     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
61     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
62     at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
63     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
64     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
65     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
66     at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:108) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
67     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
68     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
69     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
70     at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
71     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
72     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
73     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
74     at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
75     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
76     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
77     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
78     at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:106) ~[spring-boot-actuator-1.5.9.RELEASE.jar:1.5.9.RELEASE]
79     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
80     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
81     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
82     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
83     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.23.jar:8.5.23]
84     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) [tomcat-embed-core-8.5.23.jar:8.5.23]
85     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.23.jar:8.5.23]
86     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.23.jar:8.5.23]
87     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.23.jar:8.5.23]
88     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.23.jar:8.5.23]
89     at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.23.jar:8.5.23]
90     at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.23.jar:8.5.23]
91     at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-8.5.23.jar:8.5.23]
92     at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-embed-core-8.5.23.jar:8.5.23]
93     at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.23.jar:8.5.23]
94     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_151]
95     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_151]
96     at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.23.jar:8.5.23]
97     at java.lang.Thread.run(Thread.java:748) [na:1.8.0_151]
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原文地址：https://www.cnblogs.com/yanwu0527/p/8566610.html