Spring Cloud Feign 声明式服务调用
基于Netfix Feign 实现的，其整合了 Spring Cloud Ribbon 与 Spring Cloud Hystrix 组件，并且提供了一种声明式的Web服务客户端定义方式。
简单使用
- 创建新项目feign-consumer
pom.xml
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency><dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-feign</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</artifactId> </dependency> </dependencies>主类注释：
@EnableFeignClients @EnableDiscoveryClient @SpringBootApplication public class FeignConsumerApplication { public static void main(String[] args) { SpringApplication.run(FeignConsumerApplication.class, args); } }Hello-service:
@FeignClient("hello-service") public interface HelloService { @RequestMapping("/hello") String hello(); }ConsumerController :
@RestController public class ConsumerController { @Autowired HelloService helloService; @RequestMapping(value = "/feign-consumer",method = RequestMethod.GET) public String helloConsumer(){ return helloService.hello(); } }配置文件：
spring.application.name=feign-consumer server.port=9001 eureka.client.service-url.defaultZone=http://localhost:1111/eureka/
到这里已经完成了，接下来就是想ribbon那样使用了，http://localhost:9001/feign-consumer 就可以访问到helloWorld了
参数绑定
feign可以调用服务接口，可传递的参数有好几种：
例子：
String hello（@RequestParam（“name”） String name）;
String hello（@RequestParam（“name”） String name,@RequestParam（“age”） Integer age）;
String hello (@RequestBody User user);
这个就简单说明下就可以了
继承特性
这个是将接口定义从Controller中剥离出来使用的，有需要做接口定义共享才有用，这里略过╮(╯_╰)╭
Ribbon配置
对于Ribbon的属性在feign里都是可以使用的
全局配置：
ribbon.<key>=<value>
指定服务配置[与ribbon一样的]：
<client>.ribbon.key=value
Hystrix配置
配置：
hystrix.command.default.<key> = <value>
e.g.：hystrix.command.default.isolation.thread.timeoutInMilliseconds = 5000
feign.hystrix.enabled = false #关闭Hystrix功能
hystrix.command.default.execution.timeout.enabled=false #关闭熔断功能
非全局关闭Hystrix功能:
方法级别使用：
@Configuration
Public class DisableHtstrixConfiguration{
@Bean
@Scop("prototype")
public Feign.Builder feignBuilder(){
return Feign.builder();
}
}
在HelloService 的 @FeignClient注解工作configuration参数引入↑面配置
@FeignClient（name="HELLO-SERVICE",configuration = DisableHtstrixConfiguration.class）
public interface HelloService(...)
指令配置
hystrix.command.<commandKey>....=<value>
服务降级配置
e.g.：
@Component
public class HelloServiceFallback implements HelloService{
@Override
public String hello() {
return "error";
}
}
@FeignClient(name="hello-service",fallback = HelloServiceFallback.class)
public interface HelloService {
@RequestMapping("/hello")
String hello();
}
多了一个降级的接口实现类。作为降级是的调用。
其他配置
请求压缩【不考虑，碰到再说，这边的版本很低】
日志配置：
开启DEBUG日志：
logging.level.com.didispace.web.HelloService=DEBUG
#由于Feign客户端默认等级问MOME，不会有Feign调用过程中的信息。SO：主类加点东东↓
包：import feign.Logger;
依赖：
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-logging</artifactId>
</dependency>
主类：
@Bean
Logger.Level feignLoggerLevel(){
return Logger.Level.FULL;
}
亲测没什么效果╮(╯_╰)╭
就打印了下面的东东 而且就打印了一次
2018-02-26 18:10:23.187 INFO 17504 --- [hello-service-1] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@1cdd34b3: startup date [Mon Feb 26 18:10:23 CST 2018]; parent: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@77409d64
2018-02-26 18:10:23.222 INFO 17504 --- [hello-service-1] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-02-26 18:10:23.330 INFO 17504 --- [hello-service-1] c.netflix.config.ChainedDynamicProperty : Flipping property: hello-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2018-02-26 18:10:23.352 INFO 17504 --- [hello-service-1] c.n.u.concurrent.ShutdownEnabledTimer : Shutdown hook installed for: NFLoadBalancer-PingTimer-hello-service
2018-02-26 18:10:23.367 INFO 17504 --- [hello-service-1] c.netflix.loadbalancer.BaseLoadBalancer : Client:hello-service instantiated a LoadBalancer:DynamicServerListLoadBalancer:{NFLoadBalancer:name=hello-service,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2018-02-26 18:10:23.370 INFO 17504 --- [hello-service-1] c.n.l.DynamicServerListLoadBalancer : Using serverListUpdater PollingServerListUpdater
2018-02-26 18:10:23.423 INFO 17504 --- [hello-service-1] c.netflix.config.ChainedDynamicProperty : Flipping property: hello-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2018-02-26 18:10:23.425 INFO 17504 --- [hello-service-1] c.n.l.DynamicServerListLoadBalancer : DynamicServerListLoadBalancer for client hello-service initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=hello-service,current list of Servers=[windows10.microdone.cn:1234],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone; Instance count:1; Active connections count: 0; Circuit breaker tripped count: 0; Active connections per server: 0.0;]
},Server stats: [[Server:windows10.microdone.cn:1234; Zone:defaultZone; Total Requests:0; Successive connection failure:0; Total blackout seconds:0; Last connection made:Thu Jan 01 08:00:00 CST 1970; First connection made: Thu Jan 01 08:00:00 CST 1970; Active Connections:0; total failure count in last (1000) msecs:0; average resp time:0.0; 90 percentile resp time:0.0; 95 percentile resp time:0.0; min resp time:0.0; max resp time:0.0; stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@6b678d4b
2018-02-26 18:10:24.372 INFO 17504 --- [erListUpdater-0] c.netflix.config.ChainedDynamicProperty : Flipping property: hello-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2018-02-27
小杭
