Spring Cloud 是一系列框架的有序集合。它利用 Spring Boot 的开发便利性巧妙地简化了分布式系统基础设施的开发，如服务发现注册、配置中心、消息总线、负载均衡、断路器、数据监控等，都可以用 Spring Boot 的开发风格做到一键启动和部署。
SpringCloud技术概览
案例引入
01. 服务集群注册与发现
采用 Eureka Server 运行3个实例｛node01、node02、node03｝构建服务发现集群。在这种架构中，节点通过彼此互相注册来提高可用性，每个节点需要添加一个或多个有效的 serviceUrl 指向其他节点。每个节点都可被视为其他节点的副本。
EurekaServerApplication.java
三个实例均为服务注册中心，此项配置相同
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| @SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
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application.yml | node01指向另外两台服务，registerWithEureka、fetchRegistry和单实例不同需要配置为true
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| spring:
application:
name: eureka-server
server:
port: 8081
eureka:
instance:
hostname: localhost #指定当前服务实例的主机名
client:
registerWithEureka: true #当前服务实例是否要向Eureka Server注册
fetchRegistry: true #当前服务实例是否要从Eureka Server获取服务注册表
serviceUrl:
defaultZone: http://localhost:8082/eureka/,http://localhost:8083/eureka/ #指定服务注册中心的地址
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application.yml | node02指向另外两台服务
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| spring:
application:
name: eureka-server
server:
port: 8082
eureka:
instance:
hostname: localhost
client:
registerWithEureka: true
fetchRegistry: true
serviceUrl:
defaultZone: http://localhost:8081/eureka/,http://localhost:8083/eureka/
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application.yml | node03指向另外两台服务
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| spring:
application:
name: eureka-server
server:
port: 8083
eureka:
instance:
hostname: localhost
client:
registerWithEureka: true
fetchRegistry: true
serviceUrl:
defaultZone: http://localhost:8082/eureka/,http://localhost:8081/eureka/
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02. 服务提供和负载均衡调用Eureka
提供一个基于Eurka的服务注册中心，两个服务提供者之后分别使用Ribbon、Fegin方式进行调用，测试负载均衡。
服务提供者模块结构
eureka-client/src
└── main
├── java
│ └── bo
│ └── workspace
│ └── demo2
│ ├── EurekaClientApplication.java
│ └── web
│ └── EurekaClientController.java
└── resources
└── application.yml
web/EurekaClientController.java
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| /**
* 服务提供者
*/
@EnableEurekaClient
@RestController
public class EurekaClientController {
@Value("${server.port}")
private int port;
@RequestMapping(value = "api/queryUserInfo",method = RequestMethod.GET)
public String queryUserInfo(@RequestParam String userId){
return "服务提供者被调用,port="+port;
}
}
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EurekaClientApplication.java
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| @SpringBootApplication
public class EurekaClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
}
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application.yml | registerWithEureka与fetchRegistry默认为true
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| server:
port: 8002
spring:
application:
name: eureka-client
eureka:
client:
serviceUrl:
defaultZone: http://localhost:7397/eureka/
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服务注册中心模块结构
eureka-server/src
└── main
├── java
│ └── bo
│ └── workspace
│ └── demo2
│ └── EurekaServerApplication.java
└── resources
└── application.yml
EurekaServerApplication.java
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| @SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
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application.yml
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| server:
port: 7397
eureka:
instance:
hostname: localhost
client:
register-with-eureka: false #注册中心无需注册自己
fetch-registry: false #无需向本身获取服务列表
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Feign模块结构
feign/src
└── main
├── java
│ └── bo
│ └── workspace
│ └── demo2
│ ├── FeignApplication.java
│ ├── service
│ │ └── FeignService.java
│ └── web
│ └── FeignController.java
└── resources
└── application.yml
service/FeignService.java
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| @FeignClient("eureka-client")
public interface FeignService {
@RequestMapping(value = "api/queryUserInfo",method = RequestMethod.GET)
String queryUserInfo(@RequestParam String userId);
}
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web/FeignController.java
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| @RestController
public class FeignController {
@Autowired
private FeignService feignService;
@RequestMapping(value = "api/queryUserInfo",method = RequestMethod.GET)
public String queryUserInfo(@RequestParam String userId){
return feignService.queryUserInfo(userId)+"from Feign";
}
}
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FeignApplication.java
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| @SpringBootApplication
@EnableFeignClients
@EnableDiscoveryClient
@EnableEurekaClient
public class FeignApplication {
public static void main(String[] args) {
SpringApplication.run(FeignApplication.class, args);
}
}
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application.yml
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| server:
port: 9001
spring:
application:
name: feign
eureka:
client:
serviceUrl:
defaultZone: http://localhost:7397/eureka/
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