1、什么是注册中心
(1)就是首先有一个eureka server,服务的注册与发现的中心
(2)你如果写好了一个服务,就可以将其注册到eureka server上去
(3)然后别人的服务如果要调用你的服务,就可以从eureka server上查找你的服务所在的地址,然后调用
2、Eureka基本原理
(1)服务都会注册到eureka的注册表
(2)eureka有心跳机制,自动检测服务,故障时自动从注册表中摘除
(3)每个服务也会缓存euraka的注册表,即使eureka server挂掉,每个服务也可以基于本地注册表缓存,与其他服务进行通信
(4)只不过是如果eureka server挂掉了,那么无法发布新的服务了
实验步骤
(1)启动和发布一个eureka server,注册中心,web界面可以看到所有注册的服务
(2)写一个hello world服务,注册到eureka server上去
3、eureka server
(1)pom.xml
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!--eureka server -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka-server</artifactId>
</dependency>
<!-- spring boot test-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.RC1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
(2)Application
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
(3)application.yml
server:
port: 8761
eureka:
instance:
hostname: localhost
client:
registerWithEureka: false
fetchRegistry: false
serviceUrl:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
(4)访问8761端口
4、eureka client
(1)pom.xml
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.RC1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
(2)Application
@SpringBootApplication
@EnableEurekaClient
@RestController
public class SayHelloServiceApplication {
public static void main(String[] args) {
SpringApplication.run(SayHelloServiceApplication.class, args);
}
@Value("${server.port}")
String port;
@RequestMapping("/sayHello")
public String home(@RequestParam String name) {
return "hello, " + name + " from port:" +port;
}
}
(3)application.yml
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
server:
port: 8762
spring:
application:
name: service-say-hello
(4)查看eureka server界面
(5)http://localhost:8762/sayHello?name=leo
通过ribbon+rest,RestTemplate调用rest服务接口,ribbon多个服务实例的负载均衡
2、创建一个新的工程,叫做greeting-service
(1)pom.xml
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-ribbon</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.RC1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
(2)application.yml
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
server:
port: 8764
spring:
application:
name: greeting-service
(3)Application
// @EnableDiscoveryClient,向eureka注册自己作为一个服务的调用client
// 之前的服务,EnableEurekaClient,代表的是向eureka注册自己,将自己作为一个服务
@SpringBootApplication
@EnableDiscoveryClient
public class GreetingServiceApplication {
public static void main(String[] args) {
SpringApplication.run(GreetingServiceApplication.class, args);
}
// 在spring容器中注入一个bean,RestTemplate,作为rest服务接口调用的客户端
// @LoadBalanced标注,代表对服务多个实例调用时开启负载均衡
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
(4)调用say-hello-service
// 写一个服务,注入RestTemplate服务调用客户端
@Service
public class GreetingService {
@Autowired
private RestTemplate restTemplate;
// 用SAY-HELLO-SERVICE这个服务名替代实际的ip地址
// ribbon负载在多个服务实例之间负载均衡,每次调用随机挑选一个实例,然后替换服务名
public String greeting(String name) {
return restTemplate.getForObject("http://SAY-HELLO-SERVICE/sayHello?name="+name, String.class);
}
}
(5)controller
@RestController
public class GreetingControler {
@Autowired
private GreetingService greetingService;
@RequestMapping(value = "/greeting")
public String greeting(@RequestParam String name){
return greetingService.greeting(name);
}
}
(6)多次访问http://localhost:8764/greeting?name=leo,发现每次访问的端口都不一样,在多个服务实例之间负载均衡了
hystrix去做资源隔离,限流,熔断,降级
1、让greeting-service支持hystrix
(1)pom.xml
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
(2)application.xml
feign.hystrix.enabled=true
(3)SayHelloService
@FeignClient(value = "say-hello-service", fallback = SayHelloServiceFallback.class)
public interface SayHelloService {
@RequestMapping(value = "/sayHello", method = RequestMethod.GET)
public String sayHello(@RequestParam(value = "name") String name);
}
(4)SayHelloServiceFallback
@Component
public class SayHelloServiceFallback implements SayHelloService {
@Override
public String sayHello(String name) {
return "error, " + name;
}
}
(5)先保持SayHelloService启动,可以访问; 关闭SayHelloSerivce,再访问,调用失败直接走降级
包括限流,自动熔断,调用失败,都会走降级
2、hystrix dashboard
(1)pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
</dependency>
(2)Application
@EnableHystrixDashboard
@EnableCircuitBreaker
(3)http://localhost:8764/hystrix
输入http://localhost:8764/hystrix.stream和title
访问接口,会在hystrix dashboard看到访问请求
3、改造say-hello-service支持hystrix
将一个服务多个实例的指标聚合起来看,改造say-hello-service
(1)pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
(2)Application
@SpringBootApplication
@EnableEurekaClient
@RestController
@EnableHystrix
@EnableHystrixDashboard
@EnableCircuitBreaker
public class SayHelloServiceApplication {
public static void main(String[] args) {
SpringApplication.run(SayHelloServiceApplication.class, args);
}
@Value("${server.port}")
private String port;
@RequestMapping("/sayHello")
@HystrixCommand(fallbackMethod = "sayHelloFallback")
public String sayHello(String name) {
return "hello, " + name + " from port: " + port;
}
public String sayHelloFallback(String name) {
return "error, " + name
}
}
(3)locahost:8762/hystrix
输入locahost:8762/hystrix.stream,2000,title
访问这个接口
4、创建turbin工程,hystrix-turbine-server
(1)pom.xml
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-turbine</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-netflix-turbine</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
(2)Application
@SpringBootApplication
@EnableTurbine
public class HystrixTurbineServer {
public static void main(String[] args) {
new SpringApplicationBuilder(HystrixTurbineServer.class).web(true).run(args);
}
}
(3)application.yml
spring:
application.name: hystrix-terbine-server
server:
port: 8765
security.basic.enabled: false
turbine:
aggregator:
clusterConfig: default
appConfig: say-hello-service
clusterNameExpression: new String("default")
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
(4)对say-hello-service每个服务实例都访问几次
http://localhost:8762/hystrix
stream输入:http://localhost:8765/turbine.stream
在dashboard可以看到两个服务实例聚合起来的指标