标签：其它 group 工具 des ping 客户端 解析 click cat
在Spring Cloud集群中，各个角色的通信基于REST服务，在调用服务时，需要使用REST客户端，常用，除了使用Spring自带的RestTemplate，也可使用另一个REST客户端：Feign。
使用Feign时，可以使用自带注解或第三方注解来修饰接口，使得接口具有访问Web Service的能力。
Feign还支持插件式的编码器和解码器，对请求和响应进行不同的封装和解析。
Spring Cloud将Feign集成到Netflix项目中，与Eureka、Ribbon集成时，Feign就具有负载均衡的功能。
Feign在Spring Boot Web项目的使用例子可参考：《Spring Boot 2 发布与调用REST服务》
下面例子为在Spring Cloud的使用。
开发工具：IntelliJ IDEA 2019.2.3
一、服务器端
1、创建项目
IDEA中创建一个新的SpringBoot项目，名称为“spring-feign-server”，SpringBoot版本选择2.1.10，在选择Dependencies(依赖)的界面勾选Spring Cloud Discovert ->
Eureka Server，创建完成后的pom.xml配置文件自动添加SpringCloud最新稳定版本依赖，当前为Greenwich.SR3。
pom.xml完整内容如下：
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.10.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>spring-feign-server</artifactId> <version>0.0.1-SNAPSHOT</version> <name>spring-feign-server</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> <spring-cloud.version>Greenwich.SR3</spring-cloud.version> </properties> <dependencies> <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-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>
2、修改配置application.yml
修改端口号为8761；取消将自己信息注册到Eureka服务器，不从Eureka服务器抓取注册信息。
server:
port: 8761
eureka:
client:
register-with-eureka: false
fetch-registry: false
3、修改启动类代码SpringFeignServerApplication.java
增加注解@EnableEurekaServer
package com.example.springfeignserver; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; @SpringBootApplication @EnableEurekaServer public class SpringFeignServerApplication { public static void main(String[] args) { SpringApplication.run(SpringFeignServerApplication.class, args); } }
二、服务提供者
1、创建项目
IDEA中创建一个新的SpringBoot项目，除了名称为“spring-feign-provider”，其它步骤和上面创建服务器端一样。
2、修改配置application.yml
spring:
application:
name: spring-feign-provider
eureka:
instance:
hostname: localhost
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
3、添加一个实体类User.java
package com.example.springfeignprovider; public class User { String name; Integer age; public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } }
4、修改启动类代码SpringFeignProviderApplication.java
增加注解@EnableEurekaClient和@RestController；
让类在启动时读取控制台输入，决定使用哪个端口启动服务器；
增加2个测试用的控制器方法。
package com.example.springfeignprovider; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.boot.builder.SpringApplicationBuilder; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; import org.springframework.http.MediaType; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import javax.servlet.http.HttpServletRequest; import java.util.Scanner; @SpringBootApplication @EnableEurekaClient @RestController public class SpringFeignProviderApplication { public static void main(String[] args) { //SpringApplication.run(SpringFeignProviderApplication.class, args); Scanner scan = new Scanner(System.in); String port = scan.nextLine(); new SpringApplicationBuilder(SpringFeignProviderApplication.class).properties("server.port=" + port).run(args); } @RequestMapping("/hello") public String hello(HttpServletRequest request) { return "hello world." + request.getServerPort(); } @RequestMapping(value="/user/{name}", produces = MediaType.APPLICATION_JSON_VALUE) public User user(@PathVariable String name) { User u = new User(); u.setName(name); u.setAge(30); return u; } }
三、服务调用者
1、创建项目
IDEA中创建一个新的SpringBoot项目，名称为“spring-feign-invoker”，SpringBoot版本选择2.1.10，在选择Dependencies(依赖)的界面勾选Spring Cloud Discovert -> Eureka Server，Spring Cloud Routing -> OpenFeign。
pom.xml完整内容如下：
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.10.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>spring-feign-invoker</artifactId> <version>0.0.1-SNAPSHOT</version> <name>spring-feign-invoker</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> <spring-cloud.version>Greenwich.SR3</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-server</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-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>
2、修改配置application.yml
server:
port: 9000
spring:
application:
name: spring-feign-invoker
eureka:
instance:
hostname: localhost
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
3、添加一个实体类User.java
package com.example.springfeigninvoker; public class User { String name; Integer age; public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } }
4、添加一个客户端接口UserClient.java
package com.example.springfeigninvoker; import org.springframework.cloud.openfeign.FeignClient; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; //声明调用的服务名称 @FeignClient("spring-feign-provider") public interface UserClient { @RequestMapping(method = RequestMethod.GET, value = "/hello") String hello(); @RequestMapping(method = RequestMethod.GET, value = "/user/{name}") User getUser(@PathVariable("name") String name); }
5、修改启动类代码CloudInvokerApplication.java
增加注解@EnableEurekaClient和@EnableFeignClients。
package com.example.springfeigninvoker; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; import org.springframework.cloud.openfeign.EnableFeignClients; @SpringBootApplication @EnableEurekaClient @EnableFeignClients public class SpringFeignInvokerApplication { public static void main(String[] args) { SpringApplication.run(SpringFeignInvokerApplication.class, args); } }
6、添加控制器 InvokerController.java
package com.example.springfeigninvoker; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Configuration; import org.springframework.http.MediaType; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RestController; @RestController @Configuration public class InvokerController { @Autowired private UserClient userClient; @RequestMapping(value = "/invokeHello", method = RequestMethod.GET) public String invokeHello(){ return userClient.hello(); } @RequestMapping(value = "/invokeUser", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE) public String invokeUser(){ return userClient.getUser("小明").getAge().toString(); } }
四、测试
1、启动服务器端。
浏览器访问http://localhost:8761/，正常
2、启动两个服务提供者，在控制台中分别输入8080和8081启动。
（1）浏览器访问 http://localhost:8080/user/小明
输出：{"name":"小明","age":30}
（2）浏览器访问 http://localhost:8081/user/小强
输出：{"name":"小强","age":30}
3、启动服务调用者。
（1）浏览器访问http://localhost:9000/invokeHello，页面显示在下面8080和8081端口之间切换：
hello world.8080
hello world.8081
（2）浏览器访问http://localhost:9000/invokeUser，输出：
30
标签：其它 group 工具 des ping 客户端 解析 click cat
原文地址：https://www.cnblogs.com/gdjlc/p/11871438.html
