spring cloud應用

時間  2019-11-06
標籤 spring cloud 應用 欄目 Spring 简体版
原文   原文鏈接

一、什麼是註冊中心java

（1）就是首先有一個eureka server，服務的註冊與發現的中心
（2）你若是寫好了一個服務，就能夠將其註冊到eureka server上去
（3）而後別人的服務若是要調用你的服務，就能夠從eureka server上查找你的服務所在的地址，而後調用web

二、Eureka基本原理spring

（1）服務都會註冊到eureka的註冊表
（2）eureka有心跳機制，自動檢測服務，故障時自動從註冊表中摘除
（3）每一個服務也會緩存euraka的註冊表，即便eureka server掛掉，每一個服務也能夠基於本地註冊表緩存，與其餘服務進行通訊
（4）只不過是若是eureka server掛掉了，那麼沒法發佈新的服務了緩存

實驗步驟app

（1）啓動和發佈一個eureka server，註冊中心，web界面能夠看到全部註冊的服務
（2）寫一個hello world服務，註冊到eureka server上去負載均衡

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）訪問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

　　

經過ribbon+rest，RestTemplate調用rest服務接口，ribbon多個服務實例的負載均衡

二、建立一個新的工程，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註冊本身做爲一個服務的調用client
// 以前的服務，EnableEurekaClient，表明的是向eureka註冊本身，將本身做爲一個服務
@SpringBootApplication
@EnableDiscoveryClient
public class GreetingServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(GreetingServiceApplication.class, args);
    }
	
	// 在spring容器中注入一個bean，RestTemplate，做爲rest服務接口調用的客戶端
	// @LoadBalanced標註，表明對服務多個實例調用時開啓負載均衡
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

}

（4）調用say-hello-service

// 寫一個服務，注入RestTemplate服務調用客戶端
@Service
public class GreetingService {

    @Autowired
    private RestTemplate restTemplate;

	// 用SAY-HELLO-SERVICE這個服務名替代實際的ip地址
	// ribbon負載在多個服務實例之間負載均衡，每次調用隨機挑選一個實例，而後替換服務名
    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）屢次訪問http://localhost:8764/greeting?name=leo，發現每次訪問的端口都不同，在多個服務實例之間負載均衡了

　　

hystrix去作資源隔離，限流，熔斷，降級

一、讓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啓動，能夠訪問; 關閉SayHelloSerivce，再訪問，調用失敗直接走降級

包括限流，自動熔斷，調用失敗，都會走降級

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

輸入http://localhost:8764/hystrix.stream和title

訪問接口，會在hystrix dashboard看到訪問請求

三、改造say-hello-service支持hystrix

將一個服務多個實例的指標聚合起來看，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

輸入locahost:8762/hystrix.stream，2000，title

訪問這個接口

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）對say-hello-service每一個服務實例都訪問幾回

http://localhost:8762/hystrix	  

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

在dashboard能夠看到兩個服務實例聚合起來的指標
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