spring boot+spring cloud+Eureka微服务demo

2019年3月19日 332次阅读 来源: Spring Cloud

首先讲一个一定要注意的细节，spring boot和spring cloud的版本并不是完全兼容的。具体的兼容性可以参照官网
兼容性查询
如果不兼容就会出现以下错误
《spring boot+spring cloud+Eureka微服务demo》

1.编写Eureka服务microservices-discovery-eureka-demo

1.1新建spring boot项目

我这里用的idea新建spring boot项目，选择Spring Initializr，大家也可以在https://start.spring.io上创建再导入本地即可。
《spring boot+spring cloud+Eureka微服务demo》
大家根据实际情况修改group等相关信息。
《spring boot+spring cloud+Eureka微服务demo》
这里注意右上角的spring boot的版本选择。
《spring boot+spring cloud+Eureka微服务demo》
最后直接点击完成即可。
《spring boot+spring cloud+Eureka微服务demo》
创建完后首先打开pom.xml看看，然后对照加入相关依赖，其中dependencyManagement可以从官网拷贝过来。http://projects.spring.io/spring-cloud/
注意选择的spring cloud和spring boot的兼容性。

<?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.dewey</groupId>
    <artifactId>microservices-discovery-eureka-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>microservices-discovery-eureka-demo</name>
    <description>eureka service</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.13.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>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <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>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

然后打开启动类并为其加上@EnableEurekaServer

package com.dewey.microservicesdiscoveryeurekademo;

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

@SpringBootApplication
@EnableEurekaServer
public class MicroservicesDiscoveryEurekaDemoApplication {

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

然后配置eureka server，在application.yml文件中加入如下配置，其中registerWithEureka：false表示它不会自己像自己注册，fetchRegistry 为客户端是否获取eureka服务器注册表上的注册信息，默认为true，由于我们是本来就是编写eureka server，所以这里设置为flase不然启动会报错。registerWithEureka: false 和 fetchRegistry: false就代表这是一个eureka server。 当然这里也可以用系统生成的application.properties文件配置，但yaml文件的可读性要优于他，所以这里用了yaml文件配置。

server:  
  port: 8000
eureka:  
  instance:  
    hostname: localhost 
  client:  
    registerWithEureka: false 
    fetchRegistry: false 
    serviceUrl:  
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

然后我们就可以启动该eureka server了，运行启动类后在浏览器访问https://localhsot:8000/就可以看到微服务查看面板了。
《spring boot+spring cloud+Eureka微服务demo》

2.编写服务提供者microservices-provider-demo

按照上面的创建方式创建项目microservices-provider-demo，然后打开pom.xml对比添加相应依赖。

<?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.dewey</groupId>
    <artifactId>microservice-provider-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>microservice-provider-demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.13.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>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

然后打开启动类添加@EnableDiscoveryClient注解。

package com.dewey.microserviceproviderdemo;

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

@SpringBootApplication
@EnableDiscoveryClient
public class MicroserviceProviderDemoApplication {

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

然后配置该服务的端口，注册的eureka server地址等。

spring:
  application:
    name: service-provider

server:
  port: 8001

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8000/eureka/ #eureka服务注册地址

然后编写一个简单的controller。注意编写的controller一定要在启动类目录级别或下层。不然不会加载。

package com.dewey.microserviceproviderdemo.controller;

import org.springframework.web.bind.annotation.*;

@RestController
public class HelloWorld {
    @GetMapping("/test/{id}")
    public String test(@PathVariable String id){
        return "hello"+id.toString();
    }
}c

这时候启动该项目就可以在eureka server查看面板上看到该服务了。

3.编写服务提供者microservices-consumer-demo，使用ribbon。

按照上面的创建方式创建项目microservices-consumer-demo，然后打开pom.xml对比添加相应依赖。

<?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.dewey</groupId>
    <artifactId>microservice-consumer-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>microservice-consumer-demo</name>
    <description>consumer</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.13.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <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.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <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-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

然后找到启动类加上@EnableDiscoveryClient，并加入RestTemplate的bean,RestTemplate是spring用来操作rest资源的类，使用了模板模式。同时注意注解@LoadBalanced，只需要这个注解就可以为RestTemplate整合ribbon，从而实现负载均衡。而且eureka和ribbon配合使用时会将服务名自动映射成微服务的网络地址。使得大妈可伸缩性增强。具体见下面controller。

package com.dewey.microserviceconsumerdemo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class MicroserviceConsumerDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceConsumerDemoApplication.class, args);
    }
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

最后编写controller，这里restTemplate.getForObject中的url换成http://localhost:8001/test也是可以的，但是这样的话耦合度是比较高的，如果服务提供者的地址发生了变化那这个消费者就不能正常运行了。由于集成了ribbon，所以这里可以换成服务名。

package com.dewey.microserviceconsumerdemo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

@RestController
public class Test {
    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/test/{id}")
    public String test(@PathVariable String id){
        return this.restTemplate.getForObject("http://service-hello/test/"+id,String.class);
    }
}

3.编写服务提供者microservices-consumer-feign-demo，使用feign。

使用restTemplate实现rest API调用时，在代码中拼接url使得代码不够优美，而且比较长的url会使拼接变得复杂，使用feign来定义接口只需要相应的注解，非常简单易读。便于维护。
首先修改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>4.0.0</modelVersion>

    <groupId>com.dewey</groupId>
    <artifactId>microservice-consumer-feign-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>microservice-consumer-feign-demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.13.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>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <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>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

创建feign接口。@FeignClient中的name表示服务提供者的名称。注意这里不能用@GetMapping和@PostMapping等，不然会报错。大家可以试试。

package com.dewey.microserviceconsumerfeigndemo.feign;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@FeignClient(name="service-provider")
public interface testFeignClient {
    @RequestMapping(value = "/test/{id}",method = RequestMethod.GET)
    public String test(@PathVariable("id") String id);
}

配置文件application.yml

spring:
  application:
      name: client-feign

server:
  port: 8003

eureka:
  client:
    serviceUrl:
          defaultZone: http://localhost:8000/eureka/

最后编写controller

package com.dewey.microserviceconsumerfeigndemo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;


@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class MicroserviceConsumerFeignDemoApplication {

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

启动完成后我们可以通过http://localhost:8003/test/10来验证。
四个项目打包下载地址，下载即可体验微服务。

    原文作者：Spring Cloud
    原文地址: https://blog.csdn.net/godwei_ding/article/details/80561748
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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