文章目錄

• #Feign簡介
• • 1、Feign是什么？
  • 2、Feign有什么用？
  • 3、OpenFeign和Feign有什么區別？
• 1、框架搭建
• 2、導入依賴
• 3、代碼編寫
• 4、分析OpenFeign使用步驟
• • 1、導入依賴已經完成
  • 2、接口創建
  • 3、激活
• 5、測試
• 6、總結

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#Feign簡介

1、Feign是什么？

Feign是一種聲明式、模板化的HTTP客戶端。在Spring Cloud中使用Feign，可以做到使用HTTP請求訪問遠程服務，就像調用本地方法一樣的，開發者完全感知不到這是在調用遠程方法，更感知不到在訪問HTTP請求。

2、Feign有什么用？

Feign是一個聲明式的Web Service客戶端。它的出現使開發Web Service客戶端變得很簡單。使用Feign只需要創建一個接口加上對應的注解，比如：FeignClient注解。Feign有可插拔的注解，包括Feign注解和JAX-RS注解。Feign也支持編碼器和解碼器。

3、OpenFeign和Feign有什么區別？

OpenFeign對Feign進行增強支持Spring MVC注解，可以像Spring Web一樣使用HttpMessageConverters等

集成了Ribbon，可以實現客戶端的負載均衡

1、框架搭建

使用Eureka作為注冊中心 (當然nacos、consul、zookeeper也可以）；至于為什么要使用Eureka，你懂的

不是Eureka的代碼量少，只是因為我有現成的代碼

首先創建一個父工程，然后創建四個子模塊，兩個server作為注冊中心，provider模塊作為服務提供模塊，consumer只作為模擬消費模塊，不注冊進Eureka的注冊中心

2、導入依賴

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、兩個server服務模塊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模塊

<?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模塊

<?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、代碼編寫

1、兩個server模塊除了配置文件稍微不一樣外，其他都一樣

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模塊代碼編寫,框架如下

product實體類

@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使用步驟

1、導入OpenFeign依賴
2、創建接口，添加@FeignClient注解聲明調用的服務
3、激活Feign組件，在啟動類上添加@EnableFeignClients即可

1、導入依賴已經完成

2、接口創建

@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、其他代碼

application.yml

server:port: 9091spring:application:name: service-consumer-feigneureka:client:register-with-eureka: false #是否是將自己注冊到注冊中心registry-fetch-interval-seconds: 20 #Client多久去服務器拉去注冊信息 默認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、測試

成功！

6、總結

使用OpenFeign進行遠程調用還是非常符合我們程序員的習慣的，完全感知不到像在遠程調用，幫我們省掉了很多重復的代碼。

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總結

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