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" class="reference-link"> 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;
            }
        };
    }
}