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基于Spring Cloud集成OpenFeign应用feign客户端调用微服务

网友: 文章列表 2024-03-21 16:31:01

基于Spring Cloud集成OpenFeign应用feign客户端调用微服务

记录：387

场景：在基于Spring Cloud微服务架构，使用nacos实现微服务注册和配置，使用OpenFeign实现微服务之间Restful接口调用。

官网：https://spring.io/projects/spring-cloud-openfeign

源码：https://github.com/OpenFeign/feign

技术文档：https://docs.spring.io/spring-cloud-openfeign/docs/

1.初始化准备

1.1准备nacos

Nacos版本：Nacos 2.1.1。

(1)启动和登录nacos

启动命令：sh startup.sh -m standalone

地址：http://127.0.0.1:8848/nacos

用户名/口令：nacos/nacos

(2)创建命名空间

命名空间ID：aa3eebb6-daa2-4db8-9a29-03dd8a17db15

命名空间名：hub

1.2创建Maven工程

使用IntelliJ IDEA创建Maven工程。

(1)微服务名称

名称：hub-example-302-feign

(2)微服务groupId和artifactId

groupId: com.hub

artifactId: hub-example-302-feign

(3)微服务核心模块版本

spring-boot 2.6.3
spring-cloud 2021.0.1
spring-cloud-alibaba 2021.0.1.0

2.修改pom.xml

修改pom.xml，引入项目依赖Jar和管理Jar包。

2.1修改pom.xml文件

(1)spring-cloud-openfeign依赖

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency><groupId>io.github.openfeign</groupId><artifactId>feign-okhttp</artifactId>
</dependency>
<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
<dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

解析：引入sentinel，本例使用sentinel作为微服务熔断回调。

(2)nacos依赖

<!--nacos注册中心-->
<dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId><version>2021.0.1.0</version><exclusions><exclusion><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-ribbon</artifactId></exclusion></exclusions>
</dependency>
<!--nacos配置中心-->
<dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId><version>2021.0.1.0</version><exclusions><exclusion><groupId>com.alibaba.nacos</groupId><artifactId>nacos-client</artifactId></exclusion></exclusions>
</dependency>

2.2全量pom.xml文件

全量pom.xml文件请参考附录：2.11.1全量pom.xml文件

3.创建bootstrap.yml文件和配置nacos

3.1创建bootstrap.yml

server:port: 18302servlet:context-path: /hub-302-feign
spring:application:name: hub-example-302-feigncloud:nacos:discovery:server-addr: 127.0.0.1:18848username: nacospassword: nacosnamespace: aa3eebb6-daa2-4db8-9a29-03dd8a17db15group: DEFAULT_GROUPconfig:server-addr: 127.0.0.1:18848username: nacospassword: nacosnamespace: aa3eebb6-daa2-4db8-9a29-03dd8a17db15group: DEFAULT_GROUPfile-extension: yamlshared-configs:- dataId: hub-example01-config.ymlgroup: DEFAULT_GROUPrefresh: true

3.2配置nacos

Data ID：hub-example01-config.yml

Group：DEFAULT_GROUP

配置格式：YAML

配置内容：

spring:main:allow-bean-definition-overriding: truejackson:time-zone: GMT+8
server:max-http-header-size: 51200
feign:client:config:default:connectTimeout: 20000readTimeout: 90000compression:request:enabled: trueresponse:enabled: truesentinel:enabled: truehttpclient:enabled: falseokhttp:enabled: true

解析：feign.sentinel.enabled，必须为true，否则feign的FallbackFactory实现类不会生效。

4.创建启动类

4.1创建包

com.hub.example.domain：微服务使用到的DTO等实体类。

com.hub.example.controller：Controller类，发布Restful接口。

4.2启动类

包名：com.hub.example。

启动类：HubExampleFeignApplication。

(1)内容

@SpringBootApplication
@ComponentScan(basePackages = "com.hub.example.*")
@EnableFeignClients(basePackages = "com.hub.example.*")
public class HubExampleFeignApplication {public static void main(String[] args) {SpringApplication.run(HubExampleFeignApplication.class, args);}
}

(2)解析

@SpringBootApplication，SpringBoot标记启动类的注解。

@ComponentScan，扫描指定的包，将组件加载到IOC容器中。

@EnableFeignClients，扫描指定Feign接口。

5.编写Controller代码

5.1Controller代码

@RestController
@RequestMapping("/hub/example/city")
@RefreshScope
@Slf4j
public class CityController {@Autowiredprivate CityService cityService;@PostMapping("/queryCityByCityId")public ResultObj<CityDTO> queryCityByCityId(String cityId) {return cityService.queryCityByCityId(cityId);}
}

6.编写Service代码

6.1接口

public interface CityService {ResultObj<CityDTO> queryCityByCityId(String cityId);
}

6.2实现类

@Service
public class CityServiceImpl implements CityService {@Autowiredprivate CityFeignService cityFeignService;@Overridepublic ResultObj<CityDTO> queryCityByCityId(String cityId) {return cityFeignService.queryCityByCityId(cityId);}
}

7.编写feign接口和回调类以及配置类代码

7.1编写feign接口

(1)代码

@FeignClient(contextId = "cityFeignService",value = "hub-example-301-nacos",fallbackFactory = CityFeignServiceFallbackFactory.class,configuration={FeignConfiguration.class})
public interface CityFeignService {@PostMapping("/hub-301-nacos/hub/example/city/queryCityByCityId")ResultObj<CityDTO> queryCityByCityId(String cityId);
}

(2)解析

@FeignClient，标记是Feign接口。contextId，指定接口唯一标识。value，指定使用Feign接口调用的微服务名称，必须在nacos已注册。fallbackFactory，指定Feign接口调用报错时的回调类。这个类在使用熔断和降级机制时，都会回调。configuration，指定当前微服务需要传递到下一个微服务的配置信息，比如请求头信息传递到下一个微服务。

@PostMapping("/hub-301-nacos/hub/example/city/queryCityByCityId")，指定调用目标微服务的全路径。

7.2编写回调类FallbackFactory

回调类继承feign的FallbackFactory接口，并实现方法。

@Slf4j
@Component
public class CityFeignServiceFallbackFactory implements FallbackFactory<CityFeignService> {@Overridepublic CityFeignService create(Throwable cause) {log.info("调用FallbackFactory的create方法.");CityFeignServiceFallbackImpl impl = new CityFeignServiceFallbackImpl();impl.setThrowable(cause);return impl;}
}

7.3编写回调类实现类

回调实现类，实际就是实现feign接口，方法也是给回调类是使用。

@Slf4j
@Component
public class CityFeignServiceFallbackImpl implements CityFeignService {private Throwable throwable;@Overridepublic ResultObj<CityDTO> queryCityByCityId(String cityId) {log.error("CityFeignService调用微服务失败.");this.throwable.printStackTrace();return ResultObj.fail("CityFeignService调用微服务失败.");}public void setThrowable(Throwable throwable) {this.throwable = throwable;}
}

7.4编写配置类

(1)RequestInterceptor接口实现代码

@Configuration
public class FeignConfiguration implements RequestInterceptor {@Overridepublic void apply(RequestTemplate requestTemplate) {RequestAttributes reqAttributes = RequestContextHolder.currentRequestAttributes();HttpServletRequest request = ((ServletRequestAttributes) reqAttributes).getRequest();String cityCode = request.getHeader("cityCode");requestTemplate.header("cityCode", cityCode);}
}

(2)RequestInterceptor功能

编写配置类，就是实现feign的feign.RequestInterceptor接口。RequestInterceptor实际上就是一个拦截器。

功能就是使用feign接口调用微服务前，可以在请求对象中添加配置，比如添加请求头信息，传递到下一个微服务。

(3)RequestInterceptor功能和使用场景

场景：浏览器->微服务A->微服务B，调用路径中，请求头cityCode需传递到微服务A和微服务B。

默认情况下，从浏览器到微服务A的请求头信息，在微服务A调用微服务B时，请求头信息不会被传递微服务B，如需传递，就必须实现feign.RequestInterceptor接口。

8.支撑对象

8.1CityDTO 

@Data
public class CityDTO implements Serializable {private Long cityId;private String cityName;private Double landArea;private Long population;private Double gross;private String cityDescribe;private String dataYear;@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")private Date updateTime;
}

8.2ResultObj

@Data
public class ResultObj<T> implements Serializable {private int code;private boolean success;private String msg;private T data;private ResultObj(int code, T data, String msg) {this.code = code;this.data = data;
this.msg = msg;
this.success = code == 200;}public static <T> ResultObj<T> data(int code, T data, String msg) {return new ResultObj<>(code, data, msg);}
}

9.使用Postman工具测试

使用Postman工具测试。

测试地址：http://127.0.0.1:18301/hub-301-nacos/hub/example/city/queryCityByCityId

设置请求头：cityCode=310001

测试入参：cityId=20230322

返回结果： 

{"code": 200,"success": true,"msg": "执行成功","data": {"cityId": 20230322,"cityName": "杭州","landArea": null,"population": null,"gross": null,"cityDescribe": null,"dataYear": null,"updateTime": "2023-03-22 21:21:55"}
}

10.在微服务A和微服B中分别获取请求头方式

10.1注入HttpServletRequest

在Controller中注入HttpServletRequest对象。

@Autowired
private HttpServletRequest request;

10.2在方法中获取请求头

log.info("cityCode=" + request.getHeader("cityCode"));

11.附录

11.1全量pom.xml文件

<?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.hub.example</groupId><artifactId>hub-example-302-feign</artifactId><version>1.0-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.6.3</version></parent><description>集成feign框架应用</description><packaging>jar</packaging><properties><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><spring.boot.maven.plugin.version>2.6.3</spring.boot.maven.plugin.version><spring.boot.version>2.6.3</spring.boot.version><spring.cloud.version>2021.0.1</spring.cloud.version><spring.cloud.alibaba.version>2021.0.1.0</spring.cloud.alibaba.version><nacos.client.version>2.1.1</nacos.client.version><lombok.version>1.18.24</lombok.version><guava.version>30.1-jre</guava.version></properties><dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>${spring.boot.version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring.cloud.version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-dependencies</artifactId><version>${spring.cloud.alibaba.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-bootstrap</artifactId></dependency><!--nacos注册中心--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId><exclusions><exclusion><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-ribbon</artifactId></exclusion></exclusions></dependency><!--nacos配置中心--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId><exclusions><exclusion><groupId>com.alibaba.nacos</groupId><artifactId>nacos-client</artifactId></exclusion></exclusions></dependency><dependency><groupId>com.alibaba.nacos</groupId><artifactId>nacos-client</artifactId><version>${nacos.client.version}</version></dependency><!--feign配置--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>io.github.openfeign</groupId><artifactId>feign-okhttp</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${lombok.version}</version></dependency><dependency><groupId>com.google.guava</groupId><artifactId>guava</artifactId><version>${guava.version}</version></dependency></dependencies><build><finalName>${project.artifactId}</finalName><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>${spring.boot.maven.plugin.version}</version><configuration><fork>true</fork><addResources>true</addResources></configuration><executions><execution><goals><goal>repackage</goal></goals></execution></executions></plugin></plugins></build>
</project>

以上，感谢。

2023年3月22日

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