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。
GitEgg-Platform
com.gitegg.platform
1.0-SNAPSHOT
4.0.0
gitegg-platform-cloud
${project.artifactId}
${project.parent.version}
jar
com.alibaba.cloud
spring-cloud-starter-alibaba-nacos-discovery
com.alibaba.cloud
spring-cloud-starter-alibaba-nacos-config
org.springframework.cloud
spring-cloud-starter-openfeign
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:
GitEgg-Cloud
com.gitegg.cloud
1.0-SNAPSHOT
4.0.0
gitegg-service-api
${project.artifactId}
${project.parent.version}
pom
gitegg-service-base-api
gitegg-service-bigdata-api
gitegg-service-system-api
com.gitegg.platform
gitegg-platform-boot
com.gitegg.platform
gitegg-platform-cloud
com.gitegg.platform
gitegg-platform-swagger
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
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 exception() {
return Result.data(systemService.exception());
}
@PostMapping(value = "valid")
@ApiOperation(value = "参数校验测试接口")
public Result 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 nacos() {
return Result.data(nacosMaxActiveType);
}
@GetMapping(value = "api/by/id")
@ApiOperation(value = "Fegin Get调用测试接口")
public Result
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:
com.gitegg.cloud
gitegg-service-system-api
${project.parent.version}
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 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 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。
Gitee: https://gitee.com/wmz1930/GitEgg
GitHub: https://github.com/wmz1930/GitEgg
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