SpringCloud微服务实战——搭建企业级开发框架（十一）：集成OpenFeign用于微服务间调用

2022-07-10 13:43:59

作为Spring Cloud的子项目之一，Spring Cloud OpenFeign以将OpenFeign集成到Spring Boot应用中的方式，为微服务架构下服务之间的调用提供了解决方案。首先，利用了OpenFeign的声明式方式定义Web服务客户端；其次还更进一步，通过集成Ribbon或Eureka实现负载均衡的HTTP客户端。

OpenFeign 可以使消费者将提供者提供的服务名伪装为接口进行消费，消费者只需使用“Service 接口+ 注解”的方式。即可直接调用 Service 接口方法，而无需再使用 RestTemplate 了。其实原理还是使用RestTemplate，而通过Feign（伪装）成我们熟悉的习惯。

GitEgg框架除了新建Fegin服务之外，还定义实现了消费者Fegin-api，在其他微服务调用的时候，只需要引入Fegin-api即可直接调用，不需要在自己重复开发消费者调用接口。

1、在GitEgg-Platform工程的子工程gitegg-platform-cloud中引入spring-cloud-starter-openfeign依赖,重新install GitEgg-Platform工程，然后GitEgg-Cloud项目需要重新在IDEA中执行Reload All Maven Projects。

<!--?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>GitEgg-Platform</artifactid>

        <groupid>com.gitegg.platform</groupid>

        <version>1.0-SNAPSHOT</version>

    </parent>

    <modelversion>4.0.0</modelversion>

    <artifactid>gitegg-platform-cloud</artifactid>

    <name>${project.artifactId}</name>

    <version>${project.parent.version}</version>

    <packaging>jar</packaging>

    <dependencies>

        <!-- Nacos 服务注册发现-->

        <dependency>

            <groupid>com.alibaba.cloud</groupid>

            <artifactid>spring-cloud-starter-alibaba-nacos-discovery</artifactid>

        </dependency>

        <!-- Nacos 分布式配置-->

        <dependency>

            <groupid>com.alibaba.cloud</groupid>

            <artifactid>spring-cloud-starter-alibaba-nacos-config</artifactid>

        </dependency>

        <!-- OpenFeign 微服务调用解决方案-->

        <dependency>

            <groupid>org.springframework.cloud</groupid>

            <artifactid>spring-cloud-starter-openfeign</artifactid>

        </dependency>

    </dependencies>

</project>

我们从系统架构设计方面考虑，GitEgg-Cloud下的gitegg-service作为业务逻辑处理模块，gitegg-service-api作为微服务统一对外提供接口的模块，这里在测试的时候需要用到两个微服务之间的调用，我们这里在gitegg-service下gitegg-service-base里面新建测试代码，和gitegg-service-system之间相互调用。注意，这里需要说明，gitegg-service-api并不是继承gitegg-service做业务扩展，而是对外提供接口的抽象，比如现在有A、B、C三个系统A、B都需要调用C的同一个方法，如果按照业务逻辑来罗列代码的话，那么就需要在A和B中写相同的调用方法来调用C，这里我们抽出来一个api模块，专门存放调用微服务C的调用方法，在使用时，A和B只需要引入C的jar包即可直接使用调用方法。

2、在gitegg-service-system-api工程中，引入SpringBoot，SpringCloud，Swagger2的依赖，新建ISystemFeign.java和ApiSystemDTO.java，作为OpenFeign调用微服务的公共方法：

<!--?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>GitEgg-Cloud</artifactid>

        <groupid>com.gitegg.cloud</groupid>

        <version>1.0-SNAPSHOT</version>

    </parent>

    <modelversion>4.0.0</modelversion>

    <artifactid>gitegg-service-api</artifactid>

    <name>${project.artifactId}</name>

    <version>${project.parent.version}</version>

    <packaging>pom</packaging>

    <modules>

        <module>gitegg-service-base-api</module>

        <module>gitegg-service-bigdata-api</module>

        <module>gitegg-service-system-api</module>

    </modules>

    <dependencies>

        <!-- gitegg Spring Boot自定义及扩展 -->

        <dependency>

            <groupid>com.gitegg.platform</groupid>

            <artifactid>gitegg-platform-boot</artifactid>

        </dependency>

        <!-- gitegg Spring Cloud自定义及扩展 -->

        <dependency>

            <groupid>com.gitegg.platform</groupid>

            <artifactid>gitegg-platform-cloud</artifactid>

        </dependency>

        <!-- gitegg swagger2-knife4j -->

        <dependency>

            <groupid>com.gitegg.platform</groupid>

            <artifactid>gitegg-platform-swagger</artifactid>

        </dependency>

    </dependencies>

</project>

package com.gitegg.service.system.api.feign;

import com.gitegg.platform.boot.common.base.Result;

import com.gitegg.service.system.api.dto.ApiSystemDTO;

import org.springframework.cloud.openfeign.FeignClient;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PostMapping;

import org.springframework.web.bind.annotation.RequestBody;

import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(name = "gitegg-service-system")

public interface ISystemFeign {

    /**

     * OpenFeign测试Get

     *

     * @param id

     * @return

     */

    @GetMapping("/system/api/by/id")

    Result<object> querySystemById(@RequestParam("id") Long id);

    /**

     * OpenFeign测试Post

     *

     * @param apiSystemDTO

     * @return ApiSystemDTO

     */

    @PostMapping("/system/api/by/dto")

    Result<apisystemdto> querySystemByDto(@RequestBody ApiSystemDTO apiSystemDTO);

}

package com.gitegg.service.system.api.dto;

import lombok.Data;

import javax.validation.constraints.Max;

import javax.validation.constraints.Min;

import javax.validation.constraints.NotNull;

import javax.validation.constraints.Size;

@Data

public class ApiSystemDTO {

    @NotNull

    @Min(value = 10, message = "id必须大于10")

    @Max(value = 150, message = "id必须小于150")

    private Long id;

    @NotNull(message = "名称不能为空")

    @Size(min = 3, max = 20, message = "名称长度必须在3-20之间")

    private String name;

}

2、在gitegg-service-system工程中，修改SystemController.java,添加需要被微服务调用的方法:

package com.gitegg.service.system.controller;

import com.gitegg.platform.boot.common.base.Result;

import com.gitegg.service.system.dto.SystemDTO;

import com.gitegg.service.system.service.ISystemService;

import io.swagger.annotations.Api;

import io.swagger.annotations.ApiOperation;

import lombok.RequiredArgsConstructor;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.cloud.context.config.annotation.RefreshScope;

import org.springframework.web.bind.annotation.*;

import javax.validation.Valid;

@RestController

@RequestMapping(value = "system")

@RequiredArgsConstructor(onConstructor_ = @Autowired)

@Api(tags = "gitegg-system")

@RefreshScope

public class SystemController {

    private final ISystemService systemService;

    @Value("${spring.datasource.maxActive}")

    private String nacosMaxActiveType;

    @GetMapping(value = "list")

    @ApiOperation(value = "system list接口")

    public Object list() {

        return systemService.list();

    }

    @GetMapping(value = "page")

    @ApiOperation(value = "system page接口")

    public Object page() {

        return systemService.page();

    }

    @GetMapping(value = "exception")

    @ApiOperation(value = "自定义异常及返回测试接口")

    public Result<string> exception() {

        return Result.data(systemService.exception());

    }

    @PostMapping(value = "valid")

    @ApiOperation(value = "参数校验测试接口")

    public Result<systemdto> valid(@Valid @RequestBody SystemDTO systemDTO) {

        return Result.data(systemDTO);

    }

    @PostMapping(value = "nacos")

    @ApiOperation(value = "Nacos读取配置文件测试接口")

    public Result<string> nacos() {

        return Result.data(nacosMaxActiveType);

    }

    @GetMapping(value = "api/by/id")

    @ApiOperation(value = "Fegin Get调用测试接口")

    public Result<object> feginById(@RequestParam("id") String id) {

        return Result.data(systemService.list());

    }

    @PostMapping(value = "api/by/dto")

    @ApiOperation(value = "Fegin Post调用测试接口")

    public Result<object> feginByDto(@Valid @RequestBody SystemDTO systemDTO) {

        return Result.data(systemDTO);

    }

}

3、参照gitegg-service-system工程，在gitegg-service-base工程下，引入gitegg-service-system-api依赖，新建BaseController.java、GitEggBaseApplication.java、bootstrap.yml作为服务调用方：

pom.xml:

    <dependencies>

        <!-- gitegg-service-system 的fegin公共调用方法 -->

        <dependency>

            <groupid>com.gitegg.cloud</groupid>

            <artifactid>gitegg-service-system-api</artifactid>

            <version>${project.parent.version}</version>

        </dependency>

    </dependencies>

BaseController.java:

package com.gitegg.service.base.controller;

import com.gitegg.platform.boot.common.base.Result;

import com.gitegg.service.system.api.dto.ApiSystemDTO;

import com.gitegg.service.system.api.feign.ISystemFeign;

import io.swagger.annotations.Api;

import io.swagger.annotations.ApiOperation;

import lombok.RequiredArgsConstructor;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.cloud.context.config.annotation.RefreshScope;

import org.springframework.web.bind.annotation.*;

import javax.validation.Valid;

@RestController

@RequestMapping(value = "base")

@RequiredArgsConstructor(onConstructor_ = @Autowired)

@Api(tags = "gitegg-base")

@RefreshScope

public class BaseController {

    private final ISystemFeign systemFeign;

    @GetMapping(value = "api/by/id")

    @ApiOperation(value = "Fegin Get调用测试接口")

    public Result<object> feginById(@RequestParam("id") Long id) {

        return Result.data(systemFeign.querySystemById(id));

    }

    @PostMapping(value = "api/by/dto")

    @ApiOperation(value = "Fegin Post调用测试接口")

    public Result<object> feginByDto(@Valid @RequestBody ApiSystemDTO systemDTO) {

        return Result.data(systemFeign.querySystemByDto(systemDTO));

    }

}

GitEggBaseApplication.java:

package com.gitegg.service.base;

import org.mybatis.spring.annotation.MapperScan;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

import org.springframework.cloud.openfeign.EnableFeignClients;

import org.springframework.context.annotation.ComponentScan;

/**

 * gitegg-base 启动类

 */

@EnableDiscoveryClient

@EnableFeignClients(basePackages = "com.gitegg")

@ComponentScan(basePackages = "com.gitegg")

@MapperScan("com.gitegg.*.*.mapper")

@SpringBootApplication

public class GitEggBaseApplication {

    public static void main(String[] args) {

        SpringApplication.run(GitEggBaseApplication.class,args);

    }

}

bootstrap.yml:

server:

  port: 8002

spring:

  application:

    name: gitegg-service-base

  cloud:

    nacos:

      discovery:

        server-addr: 127.0.0.1:8848

      config:

        server-addr: 127.0.0.1:8848

        file-extension: yaml

        prefix: gitegg-service-system

        group: DEFAULT_GROUP

        enabled: true

4、分别启动gitegg-service-base和gitegg-service-system项目，打开浏览器，访问http://127.0.0.1:8002/doc.html（这里gitegg-service-base的端口设置为8002，所以访问gitegg-service-base的服务进行测试），在页面左侧菜单分别点击Fegin Get调用测试接口和Fegin Post调用测试接口，可以查看微服务调用成功

本文源码在https://gitee.com/wmz1930/GitEgg 的chapter-11分支。

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