文章目录

• #Feign简介
• • 1、Feign是什么？
  • 2、Feign有什么用？
  • 3、OpenFeign和Feign有什么区别？
• 1、框架搭建
• 2、导入依赖
• 3、代码编写
• 4、分析OpenFeign使用步骤
• • 1、导入依赖已经完成
  • 2、接口创建
  • 3、激活
• 5、测试
• 6、总结

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#Feign简介

1、Feign是什么？

Feign是一种声明式、模板化的HTTP客户端。在Spring Cloud中使用Feign，可以做到使用HTTP请求访问远程服务，就像调用本地方法一样的，开发者完全感知不到这是在调用远程方法，更感知不到在访问HTTP请求。

2、Feign有什么用？

Feign是一个声明式的Web Service客户端。它的出现使开发Web Service客户端变得很简单。使用Feign只需要创建一个接口加上对应的注解，比如：FeignClient注解。Feign有可插拔的注解，包括Feign注解和JAX-RS注解。Feign也支持编码器和解码器。

3、OpenFeign和Feign有什么区别？

OpenFeign对Feign进行增强支持Spring MVC注解，可以像Spring Web一样使用HttpMessageConverters等

集成了Ribbon，可以实现客户端的负载均衡

1、框架搭建

使用Eureka作为注册中心 (当然nacos、consul、zookeeper也可以）；至于为什么要使用Eureka，你懂的

不是Eureka的代码量少，只是因为我有现成的代码

首先创建一个父工程，然后创建四个子模块，两个server作为注册中心，provider模块作为服务提供模块，consumer只作为模拟消费模块，不注册进Eureka的注册中心

2、导入依赖

1、父pom

<?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.hao</groupId><artifactId>cloud-eureka-demo</artifactId><packaging>pom</packaging><version>1.0-SNAPSHOT</version><modules><module>cloud-eureka-server</module><module>cloud-eureka-server02</module><module>service-provider</module><module>service-consumer-feign</module></modules><parent><artifactId>spring-boot-starter-parent</artifactId><groupId>org.springframework.boot</groupId><version>2.4.3</version></parent><properties><spring-cloud.version>2020.0.2</spring-cloud.version></properties><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>

2、两个server服务模块pom(相同）

<?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"><parent><artifactId>cloud-eureka-demo</artifactId><groupId>com.hao</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>cloud-eureka-server02</artifactId><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</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-security</artifactId></dependency></dependencies></project>

3、provider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"><parent><artifactId>cloud-eureka-demo</artifactId><groupId>com.hao</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>service-provider</artifactId><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-client</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency></dependencies> </project>

4、consumer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"><parent><artifactId>cloud-eureka-demo</artifactId><groupId>com.hao</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><groupId>com.feign</groupId><artifactId>service-consumer-feign</artifactId><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-openfeign</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency></dependencies> </project>

3、代码编写

1、两个server模块除了配置文件稍微不一样外，其他都一样

server:port: 8080spring:application:name: cloud-eureka-serversecurity:user:name: rootpassword: root eureka:instance:hostname: eureka01prefer-ip-address: trueinstance-id: ${spring.cloud.client.ip-address}:${server.port}client:service-url:defaultZone: http://root:root@127.0.0.1:8081/eureka/ server:port: 8081spring:application:name: cloud-eureka-server02security:user:name: rootpassword: root eureka:instance:hostname: eureka02prefer-ip-address: trueinstance-id: ${spring.cloud.client.ip-address}:${server.port}client:service-url:defaultZone: http://root:root@127.0.0.1:8080/eureka/

2、product模块代码编写,框架如下

product实体类

@Data @AllArgsConstructor @NoArgsConstructor public class Product {private Integer id;private String productName;private Integer productNum;private Double productPrice; }

service

@Service public class ProductServiceImpl implements ProductService {@Overridepublic List<Product> selectProductList() {return Arrays.asList(new Product(1, "HuaWei nova3", 100, 2999.0),new Product(2, "xiaomi", 99, 1999.0),new Product(3, "vivo", 102, 2999.0));} }

application.yml

server:port: 7070 spring:application:name: service-providereureka:instance:hostname: providerprefer-ip-address: trueinstance-id: http://${spring.cloud.client.ip-address}:${server.port}client:service-url:defaultZone: http://root:root@127.0.0.1:8080/eureka/,http://root:root@127.0.0.1:8081/eureka/

4、分析OpenFeign使用步骤

1、导入OpenFeign依赖
2、创建接口，添加@FeignClient注解声明调用的服务
3、激活Feign组件，在启动类上添加@EnableFeignClients即可

1、导入依赖已经完成

2、接口创建

@FeignClient(value = "service-provider") public interface ProductService {@GetMapping(value = "/product/list")List<Product> selectProductList(); } @Service public class OrderServiceImpl implements OrderService {@Autowiredprivate ProductService productService;@Overridepublic Order selectOrderById(Integer id) {return new Order(id, "one", "china", 199D, productService.selectProductList());} } @RestController public class OrderController {@Resourceprivate OrderService orderService;@GetMapping(value ="/order/{id}")public Order getOrderById(@PathVariable("id") Integer id) {return orderService.selectOrderById(id);} }

3、激活

4、其他代码

application.yml

server:port: 9091spring:application:name: service-consumer-feigneureka:client:register-with-eureka: false #是否是将自己注册到注册中心registry-fetch-interval-seconds: 20 #Client多久去服务器拉去注册信息 默认30sservice-url:defaultZone: http://root:root@127.0.0.1:8080/eureka/,http://root:root@127.0.0.1:8081/eureka/ @Data @AllArgsConstructor @NoArgsConstructor public class Order {private Integer id;private String orderNo;private String orderAddress;private Double totalPrice;private List<Product> productList; } @Data @AllArgsConstructor @NoArgsConstructor public class Product {private Integer id;private String productName;private Integer productNum;private Double productPrice; }

5、测试

成功！

6、总结

使用OpenFeign进行远程调用还是非常符合我们程序员的习惯的，完全感知不到像在远程调用，帮我们省掉了很多重复的代码。

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