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SpringBoot2 整合 SpringCloud Feign 实例

梦想家们 2023-12-31 阅读 57



文章目录

  • 1. 简介
  • 2. 工程实例
  • 2.1 注册中心 springcloud-study-eureka-server
  • 2.1.1 依赖 pom.xml
  • 2.1.2 配置文件 application.properties
  • 2.1.3 启动类 EurekaServerApplication.java
  • 2.2 服务提供者 springcloud-study-hello-service
  • 2.2.1 依赖 pom.xml
  • 2.2.2 配置文件 application.yml
  • 2.2.3 控制器 HelloController.java
  • 2.2.4 启动类 HelloServiceApplication.java
  • 2.3 springcloud-study-feign
  • 2.3.1 依赖 pom.xml
  • 2.3.2 配置文件 application.yml
  • 2.3.3 Fegin 接口 HelloFeign
  • 2.3.4 调用 feign 接口的控制器
  • 2.3.5 启动类 FeignApplication
  • 3. 启动并测试
  • 3.1 注册中心的情况
  • 3.2 测试访问
  • 参考文献


1. 简介

Feign 是一个声明式的伪Http客户端,使用时只需要创建一个接口并注解。
Feign 默认集成了 Ribbon,并和 Eureka 结合,默认实现了负载均衡的效果。

2. 工程实例

在这篇文章: SpringBoot2 整合 SpringCloud Ribbon 实现负载均衡实例 中我们使用RestTemplate+Ribbon去消费服务,本篇文章主要讲述如何通过Feign去消费服务。

工程目录如下图所示:

SpringBoot2 整合 SpringCloud Feign 实例_maven


root 工程 spring-study,root 工程的 pom.xml 如下所示:

<?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.syrdbt</groupId>
    <artifactId>study</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>springcloud-study-eureka-server</module>
        <module>springcloud-study-feign</module>
        <module>springcloud-study-hello-service</module>
    </modules>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.7.RELEASE</version>
        <relativePath/>
    </parent>

    <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.RELEASE</spring-cloud.version>
    </properties>

    <dependencies>
        <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>

2.1 注册中心 springcloud-study-eureka-server

工程目录如下所示:

SpringBoot2 整合 SpringCloud Feign 实例_spring_02

2.1.1 依赖 pom.xml

pom.xml 的依赖如下所示:

<?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>study</artifactId>
        <groupId>com.syrdbt</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <modelVersion>4.0.0</modelVersion>

    <artifactId>eurkea-server</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
    </dependencies>
</project>

2.1.2 配置文件 application.properties

配置文件如下所示:

# 服务注册中心端口号
server.port=8761
# 服务注册中心主机名
eureka.instance.hostname=127.0.0.1
# 不向注册中心注册自己
eureka.client.register-with-eureka=false
# 不需要检索服务
eureka.client.fetch-registry=false
# 注册中心地址,会自动填充 主机名 和 端口号
eureka.client.service-url.defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

2.1.3 启动类 EurekaServerApplication.java

package com.syrdbt.study.eureka.server;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

/**
 * @author syrdbt
 * @date 2019-10-12
 */
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(EurekaServerApplication.class, args);
    }

}

2.2 服务提供者 springcloud-study-hello-service

工程目录如下所示:

SpringBoot2 整合 SpringCloud Feign 实例_maven_03

2.2.1 依赖 pom.xml

pom.xml 如下所示:

<?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>study</artifactId>
        <groupId>com.syrdbt</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>hello-service</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2.2.2 配置文件 application.yml

eureka:
  client:
    serviceUrl:
      #注册中心的地址
      defaultZone: http://localhost:8761/eureka/
server:
  #当前服务端口号
  port: 8762
spring:
  application:
    #当前应用名称,当前应用的名称
    name: service-hi

2.2.3 控制器 HelloController.java

package com.syrdbt.study.hello.service.controller;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author syrdbt
 * @date 2019-10-12
 */
@RestController
public class HelloController {
    @Value("${server.port}")
    private String port;

    @RequestMapping(value = "hello", method = RequestMethod.GET)
    public String index() {
        return "eurekaClient:Hello World " + this.port;
    }
}

2.2.4 启动类 HelloServiceApplication.java

package com.syrdbt.study.hello.service;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

/**
 * @author syrdbt
 * @date 2019-10-12
 */
@SpringBootApplication
@EnableEurekaClient
public class HelloServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(HelloServiceApplication.class, args);
    }
}

2.3 springcloud-study-feign

SpringBoot2 整合 SpringCloud Feign 实例_maven_04

2.3.1 依赖 pom.xml

<?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>study</artifactId>
        <groupId>com.syrdbt</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>feign</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-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>
</project>

2.3.2 配置文件 application.yml

application.yml:

server:
  port: 8765
spring:
  application:
    # 该服务的名字
    name: server-feign
eureka:
  client:
    serviceUrl:
      # eureka服务的地址
      defaultZone: http://localhost:8761/eureka/

2.3.3 Fegin 接口 HelloFeign

通过@ FeignClient(“服务名”),来指定调用哪个服务。下面的示例中调用了service-hi服务的“/hello”接口,HelloFeign.java 代码如下:

package com.syrdbt.study.feign;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * @author syrdbt
 * @date 2019-10-12
 */
@FeignClient(name = "service-hi")
public interface HelloFeign {

    @RequestMapping(value="/hello")
    String hello();
}

2.3.4 调用 feign 接口的控制器

HelloController.java,通过上面定义的Feign客户端 HelloFeign 来消费服务。

package com.syrdbt.study.feign.controller;

import com.syrdbt.study.feign.HelloFeign;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author syrdbt
 * @date 2019-10-12
 */
@RestController
public class HelloController {
    @Autowired
    private HelloFeign helloFeign;

    @GetMapping(value="/hello")
    public String getHi() {
        return helloFeign.hello();
    }
}

2.3.5 启动类 FeignApplication

package com.syrdbt.study.feign;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

/**
 * @author syrdbt
 * @date 2019-10-12
 */
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
@EnableDiscoveryClient
public class FeignApplication {
    public static void main(String[] args) {
        SpringApplication.run(FeignApplication.class, args);
    }
}

3. 启动并测试

需要启动4个实例。

⚠️注意:HelloServiceApplication 需要启动两个,两个的端口号分别为 8762 和 8763 。

IDEA 启动多实例教程:。

SpringBoot2 整合 SpringCloud Feign 实例_spring_05

3.1 注册中心的情况

访问 http://localhost:8761/ 。

注册中心注册的 实例如下所示:

SpringBoot2 整合 SpringCloud Feign 实例_spring_06

3.2 测试访问

访问:http://localhost:8765/hello 。

运行截图如下所示:

SpringBoot2 整合 SpringCloud Feign 实例_xml_07


SpringBoot2 整合 SpringCloud Feign 实例_xml_08

参考文献

  • SpringCloud 微服务实战 - 作者 :崔永超老师
  • https://www.fangzhipeng.com/springcloud/2018/08/03/sc-f3-feign.html


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