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