Spring集成Ribbon负载均衡遇到的问题

编程语言 2023-07-01 23:41:39 阅读次数: 0

1、注册中心Eureka

创建注册中心时，使用idea的多module创建即可，pom文件需要引入如下依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>2.7.0</version>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
    <version>3.1.3</version>
</dependency>

yml文件的配置内容如下

server:
  port: 8761 #端口号
spring:
  application:
    name: EUREKA-SERVER #服务名称
eureka:
  instance:
    hostname: localhost #服务实例地址
  client:
    register-with-eureka: false #是否像eureka注册中心进行注册
    fetch-registry: false  #是否拉取服务
    service-url:
      defaultZone: http://localhost:8761/eureka/ #注册中心的地址

启动类上需要加@EnableEurekaServer注解，表示是一个注册中心

@SpringBootApplication
@EnableEurekaServer
public class EurekaApplication {

    public static void main(String[] args) {
        SpringApplication.run(EurekaApplication.class, args);
    }

}

2、服务提供者Provider

同样使用多module工程进行创建，pom文件需要引入的依赖如下，

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    <version>3.1.3</version>
</dependency>

yml文件内容如下

spring:
  application:
    name: PROVIDER-HI
server:
  port: 8091
eureka:
  instance:
    hostname: localhost
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://localhost:8761/eureka/

启动类上需要加上@EnableEurekaClient，表示该服务不是一个注册中心

@SpringBootApplication
@EnableEurekaClient
public class ProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(ProviderApplication.class, args);
    }

}

服务提供者的接口及实现类定义如下

@RestController
public class HelloContoller {

    @GetMapping("hello")
    public String hello(){
        return "hello";
    }
}

3、服务消费者Ribbon

1、同样使用多module工程进行创建，pom文件需要加入的依赖如下

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    <version>3.1.3</version>
</dependency>

2、需要加一个配置文件，将RestTemplate交给spring容器进行管理，并使用@LoadBalance注解表示开启RIbbon的负载均衡功能。

public class RestConfiguration {
    @LoadBalanced
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

3、启动类需要加上如下注解

@SpringBootApplication
@EnableEurekaClient
public class ConsumerRibbonApplication {

    public static void main(String[] args) {
        SpringApplication.run(ConsumerRibbonApplication.class, args);
    }

}

4、然后服务层就可以使用restTemplate实现负载均衡的功能

@Resource
    private RestTemplate restTemplate;

    @GetMapping("hello")
    public String hello() {

        return restTemplate.getForObject("http://PROVIDER-HI/hello", String.class) + " world!";
    }

5、服务层就可以以服务名称的方式进行访问调用服务提供者，

@RestController
@RequestMapping("foo/")
public class Hello {

    @Resource
    private RestTemplate restTemplate;

    @GetMapping("hello")
    public String hello() {

        return restTemplate.getForObject("http://PROVIDER-HI/hello", String.class) + " world!";
    }
}

其中PROVIDER-HI便是eureka注册中心注册的服务名称

 Remark

如果ribbon调用出现无法找实例，即如下错误，就是pom文件中既引用了eureka-client又引用了ribbon的依赖；

因为eureka-client会包含ribbon相关的内容，因此只需要引入spring-cloud-starter-netflix-eureka-client，这也是为什么在spring官网中没有单独介绍spring-cloud-starter-netflix-ribbon这个坐标里面的内容。

错误引入pom文件的方式

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    <version>3.1.3</version>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
    <version>2.2.10.RELEASE</version>
</dependency>

正确引入pom文件方式

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    <version>3.1.3</version>
</dependency>

java.lang.IllegalStateException: No instances available for PROVIDER-HI

java.lang.IllegalStateException: No instances available for PROVIDER-HI
	at org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient.execute(BlockingLoadBalancerClient.java:89) ~[spring-cloud-loadbalancer-3.1.3.jar:3.1.3]
	at org.springframework.cloud.client.loadbalancer.LoadBalancerInterceptor.intercept(LoadBalancerInterceptor.java:56) ~[spring-cloud-commons-3.1.3.jar:3.1.3]
	at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:93) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.http.client.InterceptingClientHttpRequest.executeInternal(InterceptingClientHttpRequest.java:77) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:66) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:776) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:711) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:334) ~[spring-web-5.3.22.jar:5.3.22]
	at com.yangfan.consumerribbon.controller.Hello.hello(Hello.java:21) ~[classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_301]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_301]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1070) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.65.jar:4.0.FR]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.22.jar:5.3.22]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.65.jar:4.0.FR]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.22.jar:5.3.22]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1789) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.65.jar:9.0.65]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_301]

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