使用IDEA搭建springcloud微服务（四）----微服务消费方cloud-client

一、工具及说明
开发工具：IntelliJ IDEA 2018.2.2 (Ultimate Edition)
框架：spring boot 2.0.8、spring cloud Finchley.SR2

以通用户ID获取用户信息为例，搭建一套spring cloud微服务系统。
需要搭建一个父工程spring-cloud，一个服务注册中心eureka-server，两个微服务cloud-client,cloud-provider。
两个微服务均注册到服务注册中心。

二、微服务消费方的搭建
消费方cloud-client的搭建，基本和服务方cloud-provider一样，还是写全吧。

1. File—>New—>Module
   

2. 选择Spring Initializr,选择对应的JDK，
   Choose Initializr Server URL 选择 default。
   Next。
   

3. 输入项目组Group:com.cloud。
   组件名称Artifact:cloud-client。
   Type:选择Maven Project。
   修改自动生成的Package。
   Next。
   

4. dependencies选择Cloud Discovery—>Eureka Discovery，Cloud Routing—>Feign。
   Spring Boot选择你需要的版本，我这选择2.0.8。
   Next。
   

5. Project Name一般不做修改，和组件名称Artifact一样。
   Content root、Module file location 均按自动生成，不做修改。
   Finish。
   

6. 配置。
   将自动生成的application.properties更改为application.yml文件，个人习惯使用yml文件。
   rename的快捷键是Shift+F6。
   在application.yml中加入以下配置：

   server:
     port: 8082
   spring:
     application:
       name: cloud-client
   eureka:
     client:
       serviceUrl:
         defaultZone: http://user:123456@localhost:8080/eureka/      #服务注册中信地址，含有BASIC认证的用户名和密码
     instance:
       prefer-ip-address: true         #将IP注册到服务注册中心
   
   #放开所有节点
   management:
     endpoints:
       web:
         exposure:
           include: '*'
   

7. 修改pom文件。
   可以发现，pom文件中已自动引入了Eureka客户端、Feign模块依赖。
   将按以下修改，使用父工程spring-cloud的spring boot依赖。
   如果需要使用/health进行健康检查，则加入健康检查模块。
   如果需使用Tomcat运行，需要加入tomcat支持模块和web模块。

   <?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>
       <!-- 引入父工程的spring boot依赖 -->
       <parent>
           <groupId>com.cloud</groupId>
           <artifactId>spring-cloud</artifactId>
           <version>1.0</version>
       </parent>
       <groupId>com.cloud</groupId>
       <artifactId>cloud-client</artifactId>
       <version>0.0.1-SNAPSHOT</version>
       <name>cloud-client</name>
       <description>Demo project for Spring Boot</description>
   
       <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.SR2</spring-cloud.version>
       </properties>
   
       <dependencies>
           <!--web依赖-->
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-web</artifactId>
           </dependency>
   
           <!-- 注册中心客户端模块 -->
           <dependency>
               <groupId>org.springframework.cloud</groupId>
               <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
           </dependency>
   
           <!-- 健康检查模块 -->
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-actuator</artifactId>
           </dependency>
   
           <!--Feign模块-->
           <dependency>
               <groupId>org.springframework.cloud</groupId>
               <artifactId>spring-cloud-starter-openfeign</artifactId>
           </dependency>
   
           <!-- tomcat支持 -->
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-tomcat</artifactId>
               <scope>provided</scope>
           </dependency>
           
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-test</artifactId>
               <scope>test</scope>
           </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>
   
       <build>
           <plugins>
               <plugin>
                   <groupId>org.springframework.boot</groupId>
                   <artifactId>spring-boot-maven-plugin</artifactId>
               </plugin>
           </plugins>
       </build>
   
   </project>
   

8. 启动类CloudClientApplication 。
   在启动类上加入@EnableDiscoveryClient注解，声明该微服务注册到服务注册中心。
   加入@EnableFeignClients，声明使用Feign调用接口。

   import org.springframework.boot.SpringApplication;
   import org.springframework.boot.autoconfigure.SpringBootApplication;
   import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
   
   @EnableFeignClients
   @EnableDiscoveryClient
   @SpringBootApplication
   public class CloudClientApplication {
       public static void main(String[] args) {
           SpringApplication.run(CloudClientApplication.class, args);
       }
   }
   

9. 使用Tomcat启动，需创建类ServletInitializer。

   import org.springframework.boot.builder.SpringApplicationBuilder;
   import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
   
   public class ServletInitializer extends SpringBootServletInitializer {
   	@Override
   	protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
   		return application.sources(CloudClientApplication .class);
   	}
   }
   

10. 创建获取用户信息的接口,并请求服务提供方cloud-provider
    10.1 项目结构
    
    10.2 UserController

    import com.cloud.client.user.entity.User;
    import com.cloud.client.user.feign.UserFeignClient;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class UserController {
        @Autowired
        private UserFeignClient userFeignClient;
        @GetMapping("/user/{id}")
        public User findById(@PathVariable Long id) {
            User user = this.userFeignClient.findById(id);
            return user;
        }
    }
    

    10.3 User

    public class User {
        private Long id;
        private String username;
        private String name;
        private Integer age;
        private Double balance;
        private String requestId;
        public Long getId() {
            return this.id;
        }
        public void setId(Long id) {
            this.id = id;
        }
        public String getUsername() {
            return this.username;
        }
        public void setUsername(String username) {
            this.username = username;
        }
        public String getName() {
            return this.name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public Integer getAge() {
            return this.age;
        }
        public void setAge(Integer age) {
            this.age = age;
        }
        public Double getBalance() {
            return this.balance;
        }
        public void setBalance(Double balance) {
            this.balance = balance;
        }
        public String getRequestId() {
            return requestId;
        }
        public void setRequestId(String requestId) {
            this.requestId = requestId;
        }
    }
    

    10.4 UserFeignClient

    import com.cloud.client.user.entity.User;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.stereotype.Component;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import feign.hystrix.FallbackFactory;
    
    @FeignClient(name = "cloud-provider", fallbackFactory = FeignClientFallbackFactory.class)
    public interface UserFeignClient {
        @RequestMapping(value = "/{id}", method = RequestMethod.GET)
        public User findById(@PathVariable("id") Long id);
    }
    
    /**
     * UserFeignClient的fallbackFactory类，该类需实现FallbackFactory接口，并覆写create方法
     */
    @Component
    class FeignClientFallbackFactory implements FallbackFactory<UserFeignClient> {
        private static final Logger LOGGER = LoggerFactory.getLogger(FeignClientFallbackFactory.class);
    
        @Override
        public UserFeignClient create(Throwable cause) {
            return new UserFeignClient() {
                @Override
                public User findById(Long id) {
                    FeignClientFallbackFactory.LOGGER.info("fallback; reason was:", cause);
                    User user = new User();
                    user.setId(-1L);
                    user.setUsername("默认用户");
                    user.setAge(0);
                    user.setBalance((double) 0);
                    return user;
                }
            };
        }
    }