spring cloud应用

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