springCloud（二）服务提供和服务发现_springcloud如何自动发现服务uri, 不需要声明路径-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_28332595/article/details/88657895

服务提供者把自己注册到eureka（注册中心）上，服务消费者通过name从eureka上获取到真实的url，然后根据这个url 远程调用服务。

一、服务提供

（一）包结构

（二）代码

MemberServiceApp

package com.aeolusway;

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

@SpringBootApplication
@EnableEurekaClient
public class MemberServiceApp{

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

}

MemberController

package com.aeolusway.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class MemberController {

    @RequestMapping("/getUsername")
    public String getUsername(){

        return "control of ideology is so terrible";
    }
}

application.yml：注意：yml文件格式：参数名+冒号+空格+参数，必须要有空格。

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8888/eureka/
server:
  port: 8762
spring:
  application:
    name: service-member

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.aeolusway</groupId>
    <artifactId>SpringCloud-MemberService</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR1</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</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-web</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>
</project>

（三）注意

1、将服务提供者注册到eureka中，必须要先启动eureka，然后再启动服务提供者，不然会报错。

eureka注册中心搭建：https://blog.youkuaiyun.com/qq_28332595/article/details/88634340

2、先启动注册中心的main方法，访问：http://127.0.0.1:8888/，若成功，则显示如下页面:

此时application下面是No instances avaiable,然后启动服务提供者MemberServiceApp中的main方法，

访问url：http://localhost:8762/getUsername。

之后我们再访问http://127.0.0.1:8888/，就会发现这样的页面

此时application 下面是有实例了，说明我们的服务提供者注册成功。

3、注意端口一定不能重复（eureka和服务提供者的端口号）。

二、服务发现

（一）包结构

（二）代码

OrderService

package com.aeolusway;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;


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

}

OrderController

package com.aeolusway.controller;

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


@RestController
public class OrderController {
    @Autowired
    private RestTemplate restTemplate;
    @RequestMapping("/getMember")
    public String getMember(){
//        RestTemplate restTemplate = new RestTemplate();
        return restTemplate.getForObject("http://service-member/getUsername",String.class);
    }
}

application.yml

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8888/eureka/
server:
  port: 8764
spring:
  application:
    name: service-order

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.aeolusway</groupId>
    <artifactId>SpringCloud-OrderService</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR1</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</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-web</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>
</project>

访问http://localhost:8890/getMember，就可以访问到服务提供者的资源。

查看http://127.0.0.1:8888/，可以看到已经注册了两个服务：会员服务，订单服务

（三）注意

1、因为是在一台机器上模拟的情况，所以每一个服务的端口号不能一样。

2、springcloud要求每一个服务都需要经过注册中心eureka，所以订单服务（服务消费者）也需要把自身注册到eureka上。

3、各个服务之间的使用的参数名是在application.yml文件中配置的，如订单服务调用会员服务的这行代码

return restTemplate.getForObject("http://service-member/getUsername",String.class);

service-member 这个参数名称就是在会员服务（SpringCloud-MemberService这个项目之下）的application.yml中配置的。