SpringCloud學習-Spring Cloud Eureka

一、搭建服務注冊中心

1.使用idea創建springboot項目

添加依賴

2.修改pom.xml文件

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>eureka</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eureka</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR5</spring-cloud.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-netflix-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </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>

3.主類添加@EnableEurekaServer注解

通過@EnableEurekaServer注解啟動一個服務注冊中心提供給其他的應用進行對話

@EnableEurekaServer
@SpringBootApplication
public class EurekaApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaApplication.class, args);
    }

}

4.配置application.properties文件，添加一下內容

server.port=8761

eureka.client.hostname=localhost
# eureka.client.register-with-eureka=false不向注冊中心注冊自己
eureka.client.register-with-eureka=false
# eureka.client.fetch-registry=false注冊中心的職責是維護服務實例，不需要檢索服務，所以設置為false
eureka.client.fetch-registry=false
eureka.client.serviceUrl.defaultZone=http://${eureka.client.hostname}:${server.port}/eureka/

5.驗證

http://localhost:8761/

二、服務提供搭建

1.創建springboot項目，添加依賴

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>eureka-client</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eureka-client</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR5</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!-- 引入log4j2依賴 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-log4j2</artifactId>
        </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.修改application.properties文文件

server.port=8081
spring.application.name=hello-server
eureka.client.service-url.defaultZone=http://localhost:8761/eureka

3.主類添加@EnableDiscoveryClient注解

@EnableDiscoveryClient
@SpringBootApplication
public class EurekaClientApplication {

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

}

4.通過注入DiscoveryClient對象打印相關內容

@RestController
public class HelloControl {

    private final Logger logger = Logger.getLogger(String.valueOf(getClass()));

    @Autowired
    private DiscoveryClient client; // 服務發現客戶端

    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String test() {
        System.out.println(client.getServices().get(0));
        return "hello";
    }
}

5.查看注冊情況

6.訪問接口查看服務信息

http://localhost:8081/hello

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三、服務發現與消費

1.創建springboot項目

2. 添加@EnableDiscoveryClient注解讓該應用注冊為Eureka的客戶端應用，以獲得服務發現的能力。同時，在主類中創建RestTemplate的SpringBean實例，通過@LoadBalanced注解開啟客戶端負載均衡。

@EnableDiscoveryClient
@SpringBootApplication
public class RibbonConsumerApplication {
    @Bean
    // @LoadBalanced 開啟客戶端負載均衡
    @LoadBalanced
    RestTemplate restTemplate(){
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(RibbonConsumerApplication.class, args);
    }

}

3.創建ConsumerController類實現/ribbon-consumer接口、通過創建RestTemplate來實現對HELLO-SERVER服務提供的test接口進行調用。訪問地址是服務名，符合服務治理的要求。

@RestController
public class CustomerController {

    @Autowired
    RestTemplate restTemplate;

    @RequestMapping(value="/ribbon-consumer",method = RequestMethod.GET)
    public String helloConsumer(){
        return restTemplate.getForEntity("http://HELLO-SERVER/hello",String.class).getBody();

    }
}

4.在application.properties配置Eureka服務注冊中心的位置，同時設置消費者的端口為9000,

spring.application.name=ribbon-consumer
server.port=9000

eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

5.啟動服務后查看eureka，可以看到服務提供方的服務和消費方的服務

6.訪問消費者接口測試

http://localhost:9000/ribbon-consumer