spring cloud应用

时间  2019-11-06
标签 spring cloud 应用 栏目 Spring 繁體版
原文   原文链接

一、什么是注册中心java

（1）就是首先有一个eureka server，服务的注册与发现的中心
（2）你若是写好了一个服务，就能够将其注册到eureka server上去
（3）而后别人的服务若是要调用你的服务，就能够从eureka server上查找你的服务所在的地址，而后调用web

二、Eureka基本原理spring

（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）每一个服务也会缓存euraka的注册表，即便eureka server挂掉，每一个服务也能够基于本地注册表缓存，与其余服务进行通讯
（4）只不过是若是eureka server挂掉了，那么没法发布新的服务了缓存

实验步骤app

（1）启动和发布一个eureka server，注册中心，web界面能够看到全部注册的服务
（2）写一个hello world服务，注册到eureka server上去负载均衡

三、eureka servermaven

（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

四、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

　　

经过ribbon+rest，RestTemplate调用rest服务接口，ribbon多个服务实例的负载均衡

二、建立一个新的工程，叫作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注册本身做为一个服务的调用client
// 以前的服务，EnableEurekaClient，表明的是向eureka注册本身，将本身做为一个服务
@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，做为rest服务接口调用的客户端
	// @LoadBalanced标注，表明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，而后替换服务名
    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）屡次访问http://localhost:8764/greeting?name=leo，发现每次访问的端口都不同，在多个服务实例之间负载均衡了

　　

hystrix去作资源隔离，限流，熔断，降级

一、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，能够访问; 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

二、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

三、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

四、建立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每一个服务实例都访问几回

http://localhost:8762/hystrix	  

stream输入：http://localhost:8765/turbine.stream

在dashboard能够看到两个服务实例聚合起来的指标
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