Feign 在远程调用时，除了 GET 方式传递 POJO 外，还有几个很重要的功能：文件上传、调用返回图片流、传递 Token 等
文件上传
源码：https://gitee.com/laiyy0728/spring-cloud/tree/master/spring-cloud-feign/spring-cloud-feign-file
Feign 的子项目 feign-form(https://github.com/OpenFeign/feign-form) 支持文件上传，其中实现了上传所需要的 Encoder
模拟文件上传：spring-cloud-feign-file-server、spring-cloud-feign-file-client，其中 server 模拟文件服务器，作为服务提供者；client 模拟文件上传，通过 FeignClient 发送文件到文件服务器
FileClient
pom 依赖
org.springframework.cloud
spring-cloud-starter-netflix-eureka-client
org.springframework.cloud
spring-cloud-starter-openfeign
io.github.openfeign.form
feign-form
3.0.3
io.github.openfeign.form
feign-form-spring
3.0.3
配置文件
spring:
application:
name: spring-cloud-feign-file-client
eureka:
client:
service-url:
defaultZone: http://localhost:8761/eureka/
instance:
instance-id: ${spring.application.name}:${server.port}
prefer-ip-address: true
server:
port: 8888
启动类、FeignClient、配置、Controller
// 启动类
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class SpringCloudFeignFileClientApplication {
public static void main(String[] args) {
SpringApplication.run(SpringCloudFeignFileClientApplication.class, args);
}
}
// FeignClient
@FeignClient(value = "spring-cloud-feign-file-server", configuration = FeignMultipartConfiguration.class)
public interface FileUploadFeignClient {
/**
* feign 上传图片
*
* produces、consumes 必填
* 不要将 @RequestPart 写成 @RequestParam
*
* @param file 上传的文件
* @return 上传的文件名
*/
@RequestMapping(value = "/upload-file", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_UTF8_VALUE, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
String fileUpload(@RequestPart(value = "file")MultipartFile file);
}
// configuration
@Configuration
public class FeignMultipartConfiguration {
/**
* Feign Spring 表单编码器
* @return 表单编码器
*/
@Bean
@Primary
@Scope("prototype")
public Encoder multipartEncoder(){
return new SpringFormEncoder();
}
}
// Controller
@RestController
public class FileUploadController {
private final FileUploadFeignClient feignClient;
@Autowired
public FileUploadController(FileUploadFeignClient feignClient) {
this.feignClient = feignClient;
}
@PostMapping(value = "upload")
public String upload(MultipartFile file){
return feignClient.fileUpload(file);
}
}
FileServer
pom
org.springframework.cloud
spring-cloud-starter-netflix-eureka-client
配置文件
spring:
application:
name: spring-cloud-feign-file-server
eureka:
instance:
prefer-ip-address: true
instance-id: ${spring.application.name}:${server.port}
client:
service-url:
defaultZone: http://localhost:8761/eureka/
server:
port: 8889
启动类、Controller
@SpringBootApplication
@EnableDiscoveryClient
public class SpringCloudFeignFileServerApplication {
public static void main(String[] args) {
SpringApplication.run(SpringCloudFeignFileServerApplication.class, args);
}
}
// Controller 模拟文件上传的处理
@RestController
public class FileUploadController {
@PostMapping(value = "/upload-file")
public String fileUpload(MultipartFile file) {
return file.getOriginalFilename();
}
}
验证文件上传
POST MAN 调用 client 上传接口
file upload
图片流
源码：https://gitee.com/laiyy0728/spring-cloud/tree/master/spring-cloud-feign/spring-cloud-feign-file
通过 Feign 返回图片，一般是字节数组
在文件上传代码的基础上，再加上图片获取
FeignClient
/**
* 获取图片
* @return 图片
*/
@RequestMapping(value = "/get-img")
ResponseEntity getImage();
@GetMapping(value = "/get-img")
public ResponseEntity getImage(){
return feignClient.getImage();
}
FeignServer
@GetMapping(value = "/get-img")
public ResponseEntity getImages() throws IOException {
FileSystemResource resource = new FileSystemResource(getClass().getResource("/").getPath() + "Spring-Cloud.png");
HttpHeaders headers = new HttpHeaders();
headers.add("Content-Type", MediaType.APPLICATION_OCTET_STREAM_VALUE);
headers.add("Content-Disposition", "attachment; filename=Spring-Cloud.png");
return ResponseEntity.status(HttpStatus.OK).headers(headers).body(FileCopyUtils.copyToByteArray(resource.getInputStream()));
}
验证
在浏览器访问：http://localhost:8888/get-img ，实现图片流下载
Feign 传递 Headers
源码：https://gitee.com/laiyy0728/spring-cloud/tree/master/spring-cloud-feign/spring-cloud-feign-multi-params
在认证、鉴权中，无论是哪种权限控制框架，都需要传递 header，但在使用 Feign 的时候，会发现外部请求 ServiceA 时，可以获取到 header，但是在 ServiceA 调用 ServiceB 时，ServiceB 无法获取到 Header，导致 Header 丢失。
在 spring-cloud-feign-multi-params 基础上，实现传递 Header。
验证 Header 无法传递问题
post man 传递 header1
consumer 打印 header
Consumer 打印 header
provider 打印 header
Provider 打印 header
HeaderInterceptor
在 Consumer 增加 HeaderInterceptor，做 header 传递
@Component
public class FeignHeaderInterceptor implements RequestInterceptor {
@Override
public void apply(RequestTemplate template) {
if (null == getRequest()){
return;
}
template.header("oauth-token", getHeaders(getRequest()).get("oauth-token"));
}
private HttpServletRequest getRequest(){
try {
return ((ServletRequestAttributes) RequestContextHolder.currentRequestAttributes()).getRequest();
}catch (Exception e){
return null;
}
}
private Map getHeaders(HttpServletRequest request) {
Map headers = new HashMap<>();
Enumeration headerNames = request.getHeaderNames();
while (headerNames.hasMoreElements()) {
String key = headerNames.nextElement();
String value = request.getHeader(key);
headers.put(key, value);
}
return headers;
}
}
验证 header
用 postman 重新请求一遍，查看 provider 控制台打印：
provider header