JavaEE：Spring Cloud Alibaba-Nacos与Feign使用

Nacos服务器安装(单)：

JavaEE：CentOS 7中安装Nacos_無_爲的博客-CSDN博客

一、添加Spring Cloud与Spring Cloud Alibaba依赖：

1.在工程根目录pom.xml中：

<project ...>
    ...
    <properties>
        <spring-cloud-alibaba.version>2021.0.1.0spring-cloud-alibaba.version> 
        <spring-cloud.version>2021.0.3spring-cloud.version>  
    properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-loadbalancerartifactId>
        dependency>
    dependencies>
    <dependencyManagement>
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>${spring-cloud.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
            
            <dependency>
                <groupId>com.alibaba.cloudgroupId>
                <artifactId>spring-cloud-alibaba-dependenciesartifactId>
                <version>${spring-cloud-alibaba.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>
project>

二、微服务Module发布服务：

1.添加Nacos依赖，在模块工程pom.xml中：

<dependencies>
    ...
    
    <dependency>
        <groupId>com.alibaba.cloudgroupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discoveryartifactId>
    dependency>
dependencies>

2.注册服务，在application.yml中：

...
spring:
  ...
  application:
    name: nacos  #配置微服务的名称
  cloud:
    nacos:
      discovery:
        server-addr: http://192.168.83.129:8848  #Nacos服务器地址
management:
  endpoints:
    web:
      exposure:
        include: '*'

3.启动类中加@EnableDiscoveryClient：

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

4.提供服务接口：

@Controller
@RequestMapping
public class UserController {
    @RequestMapping(value = "/userList")
    @ResponseBody
    public String userList() {
        ...
    }
}

三、Web应用Module调用服务：

1.添加Feign与Nacos依赖，在模块工程pom.xml中：

<dependencies>
    ...
    
    <dependency>
        <groupId>org.springframework.cloudgroupId>
        <artifactId>spring-cloud-starter-openfeignartifactId>
    dependency>
    
    <dependency>
        <groupId>com.alibaba.cloudgroupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discoveryartifactId>
    dependency>
dependencies>

2.发现服务，在application.yml中：

...
spring:
  ...
  cloud:
    nacos:
      discovery:
        server-addr: http://192.168.83.129:8848  #Nacos服务器地址

3.启动类中加@EnableFeignClients与@EnableDiscoveryClient：

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

4.调用服务接口：

(1)定义Feign调用接口：

@FeignClient(name = "nacos"/*, fallback = */) //被调用的微服务名，fallback可配置降级处理类
public interface UserServiceClient {
    @RequestMapping(value = "/userList")
    String userList();
}

(2)测试例子：

@Controller
@RequestMapping
public class UserApi {
    @Autowired
    private UserServiceClient userServiceClient;
    @RequestMapping(value = "/getUserList")
    @ResponseBody
    public String getUserList() {
        System.out.println("Web应用被调用");
        return userServiceClient.userList();
    }
}

5.查看服务列表：