微服务治理系列- Spring Cloud alibaba 篇第4章使用 RestTemplate 实现服务的注册与发现

旧城等待， 2022-02-04 10:47 246阅读 0赞

# 概述 #

用一个简单的服务提供者和消费者案例，看懂Nacos.(对于使用过Eureka 的朋友，这个案例秒懂)

## 服务提供者 ##

## POM 依赖 ##

创建一个工程名为 `hello-spring-cloud-alibaba-provider` 的服务提供者项目，`pom.xml` 配置如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70][]

<?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.hello.sc.alibaba</groupId>
            <artifactId>hello-spring-cloud-alibaba-parent</artifactId>
            <version>1.0.0-SNAPSHOT</version>
        </parent>
    
        <artifactId>hello-spring-cloud-alibaba-provider</artifactId>
        <packaging>jar</packaging>
    
        <name>hello-spring-cloud-alibaba-provider</name>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</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-alibaba-nacos-discovery</artifactId>
            </dependency>
            
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <mainClass>com.hello.sc.alibaba.nacos.provider.NacosProviderApplication</mainClass>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>

### 创建启动类 ###

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

### 创建资源映射类 ###

通过 `@EnableDiscoveryClient` 注解表明是一个 Nacos 客户端，该注解是 Spring Cloud 提供的原生注解

@RestController
    public class ProviderResource {
    
        @GetMapping(value = "/echo/{message}")
        public String echo(@PathVariable String message) {
            return "Hello Nacos Discovery " + message;
        }
    }

## application.yml ##

spring:
      application:
        name: hello-spring-cloud-alibaba-provider
      cloud:
        nacos:
          discovery:
            server-addr: localhost:8848 #Nacos 所在的机器ip:port
    
    server:
      port: 8081
    
    management:
      endpoints:
        web:
          exposure:
            include: "*"

## 启动工程 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 1][]

![2019050716084535.png][]

通过浏览器访问 `http://localhost:8848/nacos`，即 Nacos Server 网址

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 2][]

## Nacos Starter 更多配置项信息 ##

<table> 
 <thead> 
  <tr> 
   <th>配置项</th> 
   <th>Key</th> 
   <th>默认值</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>服务端地址</td> 
   <td>spring.cloud.nacos.discovery.server-addr</td> 
   <td>无</td> 
   <td>Nacos Server 启动监听的ip地址和端口</td> 
  </tr> 
  <tr> 
   <td>服务名</td> 
   <td>spring.cloud.nacos.discovery.service</td> 
   <td>${spring.application.name}</td> 
   <td>给当前的服务命名</td> 
  </tr> 
  <tr> 
   <td>权重</td> 
   <td>spring.cloud.nacos.discovery.weight</td> 
   <td>1</td> 
   <td>取值范围 1 到 100，数值越大，权重越大</td> 
  </tr> 
  <tr> 
   <td>网卡名</td> 
   <td>spring.cloud.nacos.discovery.network-interface</td> 
   <td>无</td> 
   <td>当IP未配置时，注册的IP为此网卡所对应的IP地址，如果此项也未配置，则默认取第一块网卡的地址</td> 
  </tr> 
  <tr> 
   <td>注册的IP地址</td> 
   <td>spring.cloud.nacos.discovery.ip</td> 
   <td>无</td> 
   <td>优先级最高</td> 
  </tr> 
  <tr> 
   <td>注册的端口</td> 
   <td>spring.cloud.nacos.discovery.port</td> 
   <td>-1</td> 
   <td>默认情况下不用配置，会自动探测</td> 
  </tr> 
  <tr> 
   <td>命名空间</td> 
   <td>spring.cloud.nacos.discovery.namespace</td> 
   <td>无</td> 
   <td>常用场景之一是不同环境的注册的区分隔离，例如开发测试环境和生产环境的资源（如配置、服务）隔离等。</td> 
  </tr> 
  <tr> 
   <td>AccessKey</td> 
   <td>spring.cloud.nacos.discovery.access-key</td> 
   <td>无</td> 
   <td>当要上阿里云时，阿里云上面的一个云账号名</td> 
  </tr> 
  <tr> 
   <td>SecretKey</td> 
   <td>spring.cloud.nacos.discovery.secret-key</td> 
   <td>无</td> 
   <td>当要上阿里云时，阿里云上面的一个云账号密码</td> 
  </tr> 
  <tr> 
   <td>Metadata</td> 
   <td>spring.cloud.nacos.discovery.metadata</td> 
   <td>无</td> 
   <td>使用 Map 格式配置，用户可以根据自己的需要自定义一些和服务相关的元数据信息</td> 
  </tr> 
  <tr> 
   <td>日志文件名</td> 
   <td>spring.cloud.nacos.discovery.log-name</td> 
   <td>无</td> 
   <td>&nbsp;</td> 
  </tr> 
  <tr> 
   <td>接入点</td> 
   <td>spring.cloud.nacos.discovery.enpoint</td> 
   <td>UTF-8</td> 
   <td>地域的某个服务的入口域名，通过此域名可以动态地拿到服务端地址</td> 
  </tr> 
  <tr> 
   <td>是否集成 Ribbon</td> 
   <td>ribbon.nacos.enabled</td> 
   <td>true</td> 
   <td>一般都设置成 true 即可</td> 
  </tr> 
 </tbody> 
</table>

## 服务消费者 ##

### 概述 ###

服务消费者的创建与服务提供者大同小异，这里采用最原始的一种方式，即显示的使用 LoadBalanceClient 和 RestTemplate 结合的方式来访问。

### POM 依赖 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 3][]

<?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.hello.sc.alibaba</groupId>
            <artifactId>hello-spring-cloud-alibaba-parent</artifactId>
            <version>1.0.0-SNAPSHOT</version>
        </parent>
    
        <artifactId>hello-spring-cloud-alibaba-consumer</artifactId>
        <packaging>jar</packaging>
    
        <name>hello-spring-cloud-alibaba-consumer</name>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</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-alibaba-nacos-discovery</artifactId>
            </dependency>
            
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <mainClass>com.hello.sc.alibaba.nacos.consumer.NacosConsumerApplication</mainClass>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>

### 编写启动类 ###

package com.hello.sc.alibaba.nacos.consumer;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.context.annotation.Bean;
    import org.springframework.web.client.RestTemplate;
    
    @SpringBootApplication
    @EnableDiscoveryClient
    public class NacosConsumerApplication {
        public static void main(String[] args) {
            SpringApplication.run(NacosConsumerApplication.class,args);
        }
    
        @Bean
        public RestTemplate restTemplate() {
            return new RestTemplate();
        }
    }

### application.yml ###

spring:
      application:
        name: hello-spring-cloud-alibaba-consumer
      cloud:
        nacos:
          discovery:
            server-addr: 127.0.0.1:8848 # Nacos 所在机器的IP:port
    
    server:
      port: 9091
    
    management:
      endpoints:
        web:
          exposure:
            include: "*"

## 编写资源映射类 ##

package com.hello.sc.alibaba.nacos.consumer.rest;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.cloud.client.ServiceInstance;
    import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.client.RestTemplate;
    
    @RestController
    public class ConsumerResource {
        @Autowired
        private LoadBalancerClient loadBalancerClient;
    
        @Autowired
        private RestTemplate restTemplate;
    
        @Value("${spring.application.name}")
        private String appName;
    
        @GetMapping(value = "/echo/app/name")
        public String echo() {
            //使用 LoadBalanceClient 和 RestTemplate 结合的方式来访问
            ServiceInstance serviceInstance = loadBalancerClient.choose("hello-spring-cloud-alibaba-provider");
            String url = String.format("http://%s:%s/echo/%s", serviceInstance.getHost(), serviceInstance.getPort(), appName);
            return restTemplate.getForObject(url, String.class);
        }
    }

## 启动工程 ##

通过浏览器访问 `http://localhost:8848/nacos`，即 Nacos Server 网址

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 4][]

消费服务提供者提供的消息[http://localhost:9091/echo/app/name][http_localhost_9091_echo_app_name]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 5][]

到此，使用RestTemplate消费提供者提供的信息搭建完毕，下一章节我们将使用Feign 来实现服务之间的通信问题

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[2019050716084535.png]: /images/20220204/a6d0eb4e5ee041c492995dd11458b325.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 2]: /images/20220204/e9b804498766441284c4147fe42eec44.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 3]: /images/20220204/2183af672cb94395835a8af4a024ee0c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 4]: /images/20220204/4d241fa6fb1f468eb8a81e8a5fc7768f.png
[http_localhost_9091_echo_app_name]: http://localhost:9091/echo/app/name
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fd2VsZWFybg_size_16_color_FFFFFF_t_70 5]: /images/20220204/f21c99da71dc412392f1aa68c01a1391.png