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

傷城~ 2024-04-23 02:49 87阅读 0赞

**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][https_spring.io_projects_spring-cloud-openfeign]

**源码**：[https://github.com/OpenFeign/feign][https_github.com_OpenFeign_feign]

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

<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>
    
    <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: 18302
      servlet:
        context-path: /hub-302-feign
    spring:
      application:
        name: hub-example-302-feign
      cloud:
        nacos:
          discovery:
            server-addr: 127.0.0.1:18848
            username: nacos
            password: nacos
            namespace: aa3eebb6-daa2-4db8-9a29-03dd8a17db15
            group: DEFAULT_GROUP
          config:
            server-addr: 127.0.0.1:18848
            username: nacos
            password: nacos
            namespace: aa3eebb6-daa2-4db8-9a29-03dd8a17db15
            group: DEFAULT_GROUP
            file-extension: yaml
            shared-configs:
              - dataId: hub-example01-config.yml
                group: DEFAULT_GROUP
                refresh: 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: true
      jackson:
        time-zone: GMT+8
    server:
        max-http-header-size: 51200
    feign:
      client:
        config:
          default:
            connectTimeout: 20000
            readTimeout: 90000
      compression:
        request:
          enabled: true
        response:
          enabled: true
      sentinel:
        enabled: true
      httpclient:
        enabled: false
      okhttp:
        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 {
        @Autowired
        private 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 {
      @Autowired
      private CityFeignService cityFeignService;
      @Override
      public 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> {
      @Override
      public 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;
      @Override
      public 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 {
      @Override
      public 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][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>
            
            <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>
            
            <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>
            
            <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

[https_spring.io_projects_spring-cloud-openfeign]: https://spring.io/projects/spring-cloud-openfeign
[https_github.com_OpenFeign_feign]: https://github.com/OpenFeign/feign
[https_docs.spring.io_spring-cloud-openfeign_docs]: https://docs.spring.io/spring-cloud-openfeign/docs/
[http_127.0.0.1_8848_nacos]: http://127.0.0.1:8848/nacos
[http_127.0.0.1_18301_hub-301-nacos_hub_example_city_queryCityByCityId]: http://127.0.0.1:18301/hub-301-nacos/hub/example/city/queryCityByCityId