[SpringCloud教程]3. Eureka服務註冊中心集成

時間 2021-04-07

標籤 html java mysql git web spring sql apache json 後端欄目 HTML 简体版

原文原文鏈接

新微服務項目多半採用Nacos做爲服務註冊與發現中心，可是舊項目可能使用Eureka、zookeeper、Consul、Nacos做爲服務註冊中心。
新項目建議使用Nacos做爲服務註冊中心html

SpringCloud教程合集: https://www.cnblogs.com/spzmmd/tag/微服務教程/
案例項目地址: https://gitee.com/spzmmd/spring-cloud-demo

根項目創建

創建一個maven項目，刪除src目錄，而後編輯pom.xml文件
其中核心部分就是SpringCloud、SpringBoot、SpringCloudAlibaba的版本號
- Spring Cloud Version: Spring Cloud Hoxton.SR8
- Spring Cloud Alibaba Version: 2.2.5.RELEASE
- Spring Boot Version: 2.3.2.RELEASE

<?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>4.0.0</modelVersion>

    <groupId>com.spz.demo</groupId>
    <artifactId>spring-cloud-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>pom</packaging>

    <modules>
        <!-- <module>api-common</module>
        <module>ms-provider</module>
        <module>ms-consumer</module>
        <module>eureka-server</module> -->
    </modules>

    <!-- 統一管理jar包版本 -->
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>

        <junit.version>4.12</junit.version>
        <log4j.version>1.2.17</log4j.version>
        <lombok.version>1.16.18</lombok.version>
        <mysql.version>8.0.16</mysql.version>
        <druid.version>1.1.16</druid.version>
        <mybatis.plus.version>3.3.2</mybatis.plus.version>
        <jackson-version>2.9.9</jackson-version>
    </properties>

    <dependencyManagement>
        <dependencies>

            <!-- Spring Boot-->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.3.2.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <!-- Spring Cloud -->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR8</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <!-- Spring Cloud Alibaba -->
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.5.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>${mysql.version}</version>
            </dependency>

            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>${druid.version}</version>
            </dependency>

            <dependency>
                <groupId>com.baomidou</groupId>
                <artifactId>mybatis-plus-boot-starter</artifactId>
                <version>${mybatis.plus.version}</version>
            </dependency>


            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>${log4j.version}</version>
            </dependency>

            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>${lombok.version}</version>
                <optional>true</optional>
            </dependency>

        </dependencies>
    </dependencyManagement>
</project>

項目結構

eureka-server: Eureka服務端
ms-consumer: 服務消費者
ms-provider: 服務提供者
api-common: 公共模塊

Eureka 服務註冊中心服務端(eureka-server)

首先須要在根pom.xml的modules標籤下加入該模塊:java

<modules>
    <module>api-common</module>
    <!-- 
    <module>ms-provider</module>
    <module>ms-consumer</module> -->
    <module>eureka-server</module>
</modules>

單節點 Eureka Server 節點搭建

在根項目下創建eureka-server目錄，而後在eureka-server目錄下創建pom.xml，粘貼以下代碼:

<?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>4.0.0</modelVersion>
    <parent>
        <groupId>com.spz.demo</groupId>
        <artifactId>spring-cloud-demo</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>eureka-server</artifactId>
    <packaging>jar</packaging>

    <description>Eureka註冊中心</description>

    <dependencies>

        <!-- Eureka Server-->
        <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-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>com.spz.demo</groupId>
            <artifactId>api-common</artifactId>
            <version>${project.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>

創建src/main/java和src/main/resources目錄
在src/main/java目錄下創建包com.spz.demo.scloud.register.eureka

在eureka包下創建啓動類 RegisterServerEureka.java

package com.spz.demo.scloud.register.eureka;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

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

在src/main/resources目錄下創建application.properties文件
- eureka.client.service-url.defaultZone: 這裏只須要配置除本身之外的其餘服務端節點，由於是將本節點註冊給其餘註冊中心，來實現互相註冊的高可用集羣

server.port=6001
spring.application.name=@project.artifactId@

# Eureka 配置
# Eureka Server 實例 hostname
eureka.instance.hostname=eureka6001
# 服務端不須要註冊本身
eureka.client.register-with-eureka=false
# 服務端不須要檢索服務
eureka.client.fetch-registry=false
# Eureka Server 向其餘服務端註冊本身，實現Eureka的高可用集羣
eureka.client.service-url.defaultZone=http://eureka6002:6002/eureka,http://eureka6003:6003/eureka
# 關閉自我保護機制，保證不可用服務被及時踢除，建議生產環境保持默認
#eureka.server.enable-self-preservation=false
#eureka.server.eviction-interval-timer-in-ms=2000

高可用 Eureka Server 集羣實現

eureka 服務端實例實現高可用集羣的方法是多個Eureka Server節點互相註冊。好比A、B、C三個節點，A把本身做爲Eureka客戶端註冊到B、C節點；B把本身註冊到A、C節點；C把本身註冊到A、B節點。這樣三個節點互相具有其餘服務端節點的信息，客戶端列表數據也至關於保存了三分，這時候某個服務端節點失效，並不會形成客戶端信息缺失，由此實現了高可用集羣。下面介紹高可用集羣實現方法：mysql

配置Eureka 服務端節點所屬服務器的hosts，這裏採用本地部署多個Eureka服務端的方案代替
假設三個Eureka服務端節點的hostname分別爲eureka600一、eureka600二、eureka6003。(注意：不配置hosts會致使Eureka集羣沒法進行備份，由於必須保證每一個節點的hostname不一樣)

127.0.0.1  eureka6001
127.0.0.1  eureka6002
127.0.0.1  eureka6003

IDEA方式啓動 - eureka6001節點配置

vm options:

-Dserver.port=6001
-Deureka.instance.hostname=eureka6001
-Deureka.client.service-url.defaultZone=http://eureka6002:6002/eureka,http://eureka6003:6003/eureka

IDEA方式啓動 - eureka6002節點配置

vm options:git

-Dserver.port=6002
-Deureka.instance.hostname=eureka6002
-Deureka.client.service-url.defaultZone=http://eureka6001:6001/eureka,http://eureka6003:6003/eureka

IDEA方式啓動 - eureka6003節點配置

vm options:web

-Dserver.port=6003
-Deureka.instance.hostname=eureka6003
-Deureka.client.service-url.defaultZone=http://eureka6002:6002/eureka,http://eureka6001:6001/eureka

IDEA方式啓動
啓動RegisterServerEureka600一、RegisterServerEureka600二、RegisterServerEureka6003便可，啓動後分別訪問三個節點的管理端：spring
例如訪問 http://eureka6001:6001/sql

如圖eureka6001節點的DS Replicas出現了另外兩個相鄰節點，說明這三個節點組成了一個集羣，這時候訪問另外兩個節點的管理頁，也能一樣看到DS Replicas裏出現其餘兩個節點。另外，當有客戶端註冊進服務端時，三個服務端節點裏應該有同一份的客戶端列表信息。至此Eureka集羣搭建成功。apache

服務提供者集羣(ms-provider)

首先須要在根pom.xml的modules標籤下加入該模塊:json

<modules>
    <module>api-common</module>
    <module>ms-provider</module>
    <!-- <module>ms-consumer</module> -->
    <module>eureka-server</module>
</modules>

單節點ms-provider搭建

在根項目下創建ms-provider目錄，而後在ms-provider目錄下創建pom.xml，粘貼以下代碼：

<?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>4.0.0</modelVersion>
    <parent>
        <groupId>com.spz.demo</groupId>
        <artifactId>spring-cloud-demo</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>ms-provider</artifactId>
    <packaging>jar</packaging>

    <description>服務提供者模塊</description>

    <dependencies>

        <!-- sleuth zipkin 服務追蹤 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zipkin</artifactId>
        </dependency>

        <!-- eureka client -->
        <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-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>com.spz.demo</groupId>
            <artifactId>api-common</artifactId>
            <version>${project.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>

創建src/main/java和src/main/resources目錄
在src/main/resources下創建application.properties文件
- eureka.client.service-url.defaultZone: 這裏配置的是Eureka服務端集羣，啓動後該服務將把本身註冊進Eureka註冊中心集羣
- spring.application.name: 將做爲服務名註冊進Eureka註冊中心(使用RestTemplate+負載均衡來調用Eureka服務時，服務名不能有下劃線)

server.port=8001
spring.application.name=MS-PROVIDER

# 服務追蹤
#spring.zipkin.base-url=http://localhost:9411
#採樣率值介於 0 到 1 之間，1 則表示所有采集
#spring.sleuth.sampler.probability=1

# eureka 配置
# 是否將本身註冊進 EurekaServer 默認爲true
eureka.client.register-with-eureka=true
# 是否從 EurekaServer 抓取已有的註冊信息，默認爲true。單節點無所謂，集羣必須設置爲true才能配合ribbon使用負載均衡
eureka.client.fetchRegistry=true
eureka.client.service-url.defaultZone=http://eureka6001:6001/eureka,http://eureka6002:6002/eureka,http://eureka6003:6003/eureka
# 實例ID
eureka.instance.instance-id=${spring.application.name}-${server.port}
# 訪問路徑能夠顯示IP地址
eureka.instance.prefer-ip-address=true
# Eureka客戶端向服務端發送心跳的時間間隔，單位爲秒(默認是30秒)
eureka.instance.lease-renewal-interval-in-seconds=1
# Eureka服務端在收到最後一次心跳後等待時間上限，單位爲秒(默認是90秒)，超時將剔除服務
eureka.instance.lease-expiration-duration-in-seconds=10

在src/main/java目錄下創建包com.spz.demo.scloud.provider
在provider包下創建其餘包、類和啓動類

IndexController.java

package com.spz.demo.scloud.provider.controller;

import com.spz.demo.scloud.common.core.bean.RestBean;
import com.spz.demo.scloud.common.service.AppService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("")
public class IndexController {

    @Autowired
    private AppService appService;

    /**
    * 獲取項目信息
    * @return
    */
    @RequestMapping("/projectInfo")
    public RestBean projectInfo(){
        String msg = appService.instanceNameAndPort();
        return RestBean.ok(msg);
    }

}

AppServiceImpl.java
注意該該類實現的AppService.java接口存放於api-common包，該包代碼請在此處查看(https://gitee.com/spzmmd/spring-cloud-demo)

package com.spz.demo.scloud.provider.service;

import com.spz.demo.scloud.common.service.AppService;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

/**
* App Service 接口實現類
*/
@Service
public class AppServiceImpl implements AppService {

    /**
    * 項目端口
    */
    @Value("${server.port}")
    private Integer projectServerPort;

    /**
    * 項目名稱
    */
    @Value("${spring.application.name}")
    private String projectApplicationName;

    @Override
    public String instanceNameAndPort(){
        return projectApplicationName + ":" + projectServerPort;
    }

}

ProviderApp.java 啓動類

package com.spz.demo.scloud.provider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

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

集羣實現

客戶端服務(這裏是本機，因此只須要配置一次，若是是不一樣服務器則須要配置)也須要配置hosts，否則沒法訪問Eureka註冊中心集羣後端

127.0.0.1  eureka6001
127.0.0.1  eureka6002
127.0.0.1  eureka6003

IDEA方式啓動 - 8001節點

vm options:

-Dserver.port=8001
-Deureka.client.service-url.defaultZone=http://eureka6001:6001/eureka,http://eureka6002:6002/eureka,http://eureka6003:6003/eureka

IDEA方式啓動 - 8002節點

vm options:

-Dserver.port=8002
-Deureka.client.service-url.defaultZone=http://eureka6001:6001/eureka,http://eureka6002:6002/eureka,http://eureka6003:6003/eureka

IDEA方式啓動
啓動ProviderApp800一、ProviderApp8002便可，啓動後分別訪問三個註冊中心的管理端：
訪問三個註冊中心管理端，應該都可以看到這裏有相同的客戶端信息
- MS-PROVIDER-8001: 這裏是在application.properties裏的"eureka.instance.instance-id"配置的，也便是實例ID
- MS-PROVIDER: 這裏是在application.properties裏的"spring.application.name"配置的,也便是服務名(使用RestTemplate+負載均衡來調用Eureka服務時，服務名不能有下劃線)

服務提供者集羣搭建完成

服務消費者實例(ms-consumer)

首先須要在根pom.xml的modules標籤下加入該模塊:

<modules>
    <module>api-common</module>
    <module>ms-provider</module>
    <module>ms-consumer</module>
    <module>eureka-server</module>
</modules>

單節點ms-consumer搭建

在根項目下創建ms-consumer目錄，而後在ms-consumer目錄下創建pom.xml，粘貼以下代碼：

<?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>4.0.0</modelVersion>
    <parent>
        <groupId>com.spz.demo</groupId>
        <artifactId>spring-cloud-demo</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>ms-consumer</artifactId>
    <packaging>jar</packaging>

    <description>消費者模塊</description>

    <dependencies>

        <!-- sleuth zipkin 服務追蹤 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zipkin</artifactId>
        </dependency>

        <!-- eureka client -->
        <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-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>com.spz.demo</groupId>
            <artifactId>api-common</artifactId>
            <version>${project.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>

創建src/main/java和src/main/resources目錄
在src/main/resources下創建application.properties文件
- eureka.client.service-url.defaultZone: 這裏配置的是Eureka服務端集羣，啓動後該服務將把本身註冊進Eureka註冊中心集羣
- spring.application.name: 將做爲服務名註冊進Eureka註冊中心

server.port=7001
spring.application.name=MS-CONSUMER

# 服務追蹤
#spring.zipkin.base-url=http://localhost:9411
#採樣率值介於 0 到 1 之間，1 則表示所有采集
#spring.sleuth.sampler.probability=1

# Eureka 註冊中心配置
# 是否將本身註冊進 Eureka Server 默認爲true
eureka.client.register-with-eureka=true
# 實例ID
eureka.instance.instance-id=${spring.application.name}-${server.port}
# 訪問路徑能夠顯示IP地址
eureka.instance.prefer-ip-address=true
# 是否從 Eureka Server 抓取已有的註冊信息，默認爲true 單節點無所謂，集羣必須設置爲true才能配合ribbon使用負載均衡
eureka.client.fetchRegistry=true
# Eureka Server 集羣
eureka.client.service-url.defaultZone=http://eureka6001:6001/eureka,http://eureka6002:6002/eureka,http://eureka6003:6003/eureka

在src/main/java目錄下創建包com.spz.demo.scloud.consumer
在consumer包下創建其餘包、類和啓動類

RestTemplateConfig.java

RestTemplate用於消費者遠程訪問服務提供者提供的接口
注意須要@LoadBalanced註解，不然RestTemplate沒法從服務提供者集羣裏獲取實例

package com.spz.demo.scloud.consumer.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
/**
* RestTemplate 配置
*/
@Configuration
public class RestTemplateConfig {
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

DiscoveryEurekaController.java
用於測試Eureka註冊中心

package com.spz.demo.scloud.consumer.controller;

import com.spz.demo.scloud.common.core.bean.RestBean;
import com.spz.demo.scloud.common.service.AppService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.net.URI;
import java.util.List;

/**
* 註冊中心 - Eureka - 測試接口
*/
@Slf4j
@RestController
@RequestMapping("/discovery/eureka")
public class DiscoveryEurekaController {

    @Autowired
    private DiscoveryClient discoveryClient;

    @Autowired
    private RestTemplate restTemplate;

    /**
    * 服務遠程調用測試 - 使用 RestTemplate
    * @see AppService#instanceNameAndPort()
    * @return
    */
    @RequestMapping("/appService/projectInfo")
    public RestBean appServiceProjectInfo(){
        RestBean restBean = restTemplate.postForObject("http://MS-PROVIDER/projectInfo",null, RestBean.class);
        return restBean;
    }

    /**
    * 獲取已在 Eureka Server 註冊的服務名稱列表
    * 注意不是服務名下的實例名稱列表，是 Eureka的Application名稱列表
    * @return
    */
    @RequestMapping("/services")
    public RestBean services(){
        List<String> services = discoveryClient.getServices();
        return RestBean.ok(services);
    }

    /**
    * 根據名稱獲取實例列表
    * 1. 如多個服務註冊到Eureka服務端，他們的名稱均爲MS-PROVIDER，則使用MS-PROVIDER可查詢出全部已註冊實例
    * 2. 獲取到ServiceInstance對象裏包含實例的ServiceId、host、port、uri等
    * @param name eg. MS-PROVIDER
    * @return
    */
    @GetMapping("/instances/{name}")
    public RestBean instancesByName(@PathVariable(name = "name", required = true) String name){
        List<ServiceInstance> instances = discoveryClient.getInstances(name);
        return RestBean.ok(instances);
    }
}

ConsumerApp.java 啓動類

package com.spz.demo.scloud.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

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

IDEA方式啓動 - 7001節點

vm options:

-Dserver.port=7001
-Deureka.client.service-url.defaultZone=http://eureka6001:6001/eureka,http://eureka6002:6002/eureka,http://eureka6003:6003/eureka

啓動後，不斷訪問以下地址

http://localhost:7001/discovery/eureka/appService/projectInfo

能夠發現返回的端口號會在8001和8002之間交替變化，說明服務提供者註冊的兩個實例都可以訪問

{
"code": 2000,
"message": "MS-PROVIDER:8001",
"data": null
}

{
"code": 2000,
"message": "MS-PROVIDER:8002",
"data": null
}

集羣實現

於服務提供者集羣實現方式類似，這裏再也不贅述

參考

使用RestTemplate+負載均衡來調用Eureka服務時，服務名稱不能有下劃線！！
Eureka自我保護機制
 https://www.cnblogs.com/xishuai/p/spring-cloud-eureka-safe.html

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