springcloud-搭建服务注册中心

创建服务注册中心

1.创建一个springboot

　　命名为eureka-server

　　1）添加Eureka依赖

　　　　pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.</modelVersion>
  <groupId>springcloud</groupId>
  <artifactId>springcloud-Eureka</artifactId>
  <version>0.0.-SNAPSHOT</version>
  <name>eureka-server</name>
  <description>a part of the springcloud</description>

  <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>1.5..RELEASE</version>
      <relativePath/> <!-- lookup parent from repository -->
  </parent>

  <properties>
      <project.build.sourceEncoding>UTF-</project.build.sourceEncoding>
      <project.reporting.outputEncoding>UTF-</project.reporting.outputEncoding>
      <java.version>1.8</java.version>
  </properties>

  <dependencies>
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter</artifactId>
      </dependency>
      <dependency>
          <groupId>org.springframework.cloud</groupId>
          <artifactId>spring-cloud-starter-eureka-server</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.SR3</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>

</project>

　　2）启动服务中心

　　Spring Boot的入口类上添加一个@EnableEurekaServer注解

2.配置服务注册中心

　　在application.properties：

server.port=1111　　
eureka.instance.hostname=localhost　　#设置该服务注册中心的hostname
eureka.client.register-with-eureka=false　　#默认情况下，这个应用会向注册中心（也是它自己）注册它自己，设置为false表示禁止这种默认行为
eureka.client.fetch-registry=false　　#表示不去检索其他的服务，因为服务注册中心本身的职责就是维护服务实例，它也不需要去检索其他服务
eureka.client.service-url.defaultZone=http://${eureka.instance.hostname}:${server.port}/eureka/

注册服务提供者

1.pom

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.</modelVersion>
    <groupId>org.sang</groupId>
    <artifactId>provider</artifactId>
    <version>0.0.-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>provider</name>
    <description>Demo project for Spring Boot</description>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5..RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <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>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR3</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>
</project>

2.创建应用入口

@RestController
public class HelloController {
    private final Logger logger = Logger.getLogger(getClass());
    @Autowired
    private DiscoveryClient client;

    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String index() {
        List<ServiceInstance> instances = client.getInstances("hello-service");
        for (int i = ; i < instances.size(); i++) {
            logger.info("/hello,host:" + instances.get(i).getHost() + ",service_id:" + instances.get(i).getServiceId());
        }
        return "Hello World";
    }
}

3.application

@EnableDiscoveryClient
@SpringBootApplication
public class ProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(ProviderApplication.class, args);
    }
}

4.配置

spring.application.name=hello-service
eureka.client.service-url.defaultZone=http://localhost:1111/eureka

测试

刷新刚才的http://localhost:1111，就能看到注册成功的服务应用了

如果搭建高可用负载均衡？

　　给eureka-server配置两个application_1.properties，application_2.properties,对应的设置

server.port=
eureka.instance.hostname=peer1
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
eureka.client.service-url.defaultZone=http://peer2:1112/eureka/

server.port=
eureka.instance.hostname=peer2
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
eureka.client.service-url.defaultZone=http://peer1:1111/eureka/

.在peer1的配置文件中，让它的service-url指向peer2，在peer2的配置文件中让它的service-url指向peer1
.为了让peer1和peer2能够被正确的访问到，我们需要在C:\Windows\System32\drivers\etc目录下的hosts文件总添加两行配置，如下:
127.0.0.1 peer1
127.0.0.1 peer2
.由于peer1和peer2互相指向对方，实际上我们构建了一个双节点的服务注册中心集群

　　provider的pom变为

spring.application.name=hello-service
eureka.client.service-url.defaultZone=http://peer1:1111/eureka,http://peer2:1112/eureka

负载均衡：生产者消费者

　　1.服务的发现由Eureka客户端来完成，而服务的消费由Ribbon来完成。Ribbo是一个基于HTTP和TCP的客户端负载均衡器，当我们将Ribbon和Eureka一起使用时，Ribbon会从Eureka注册中心去获取服务端列表，然后进行轮询访问以到达负载均衡的作用，服务端是否在线这些问题则交由Eureka去维护

　　2.服务springcloud-Eureka-provider生成jar，通过类似代码创建jar,运行后生产者工作结束

java -jar provider-0.0.-SNAPSHOT.jar --server.port=
java -jar provider-0.0.-SNAPSHOT.jar --server.port=

　　3.创建消费者，Ribbon

　　1）pom

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.</modelVersion>

    <groupId>org.sang</groupId>
    <artifactId>ribbon-consumer</artifactId>
    <version>0.0.-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>ribbon-consumer</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5..RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Dalston.SR3</spring-cloud.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>${spring-cloud.version}</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>
</project>

　　2）配置启动类

@SpringBootApplication
@EnableDiscoveryClient//表示该应用是一个Eureka客户端应用，这样该应用就自动具备了发现服务的能力
public class RibbonConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(RibbonConsumerApplication.class, args);
    }
    @LoadBalanced//表示开启客户端负载均衡
    @Bean//RestTemplate可以帮助我们发起一个GET或者POST请求
    RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

　　3）创建controller

@RestController
public class ConsumerController {
    @Autowired
    RestTemplate restTemplate;
    @RequestMapping(value = "/ribbon-consumer",method = RequestMethod.GET)
    public String helloController() {
        return restTemplate.getForEntity("http://HELLO-SERVICE/hello", String.class).getBody();
    }
}

　　4）application.properties

spring.application.name=ribbon-consumer
server.port=
eureka.client.service-url.defaultZone=http://localhost:1111/eureka

　　5）测试

　　程序运行后，看到服Eurak已有了三个服务，其中消费者服务点开后，访问的url会在8001,8002两个服务提供者中来回调用

注意：

　　1）服务续约

在注册完服务之后，服务提供者会维护一个心跳来不停的告诉Eureka Server：“我还在运行”，以防止Eureka Server将该服务实例从服务列表中剔除，这个动作称之为服务续约，和服务续约相关的属性有两个，如下：

eureka.instance.lease-expiration-duration-in-seconds=
eureka.instance.lease-renewal-interval-in-seconds=

第一个配置用来定义服务失效时间，默认为90秒，第二个用来定义服务续约的间隔时间，默认为30秒。