Spring Cloud Feign的文件上传实现

Original: 翟永超程序猿DD 2019-07-13

在Spring Cloud封装的Feign中并不直接支持传文件，但可以通过引入Feign的扩展包来实现，本文就来具体说说如何实现。

服务提供方的实现比较简单，就按Spring MVC的正常实现方式即可，比如：

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class Application {
@RestController
public class UploadController {
@PostMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public String handleFileUpload(@RequestPart(value = "file") MultipartFile file) {
return file.getName();
}
}
public static void main(String[] args) {
new SpringApplicationBuilder(Application.class).web(true).run(args);
}
}

在服务消费方由于会使用Feign客户端，所以在这里需要在引入feign对表单提交的依赖，具体如下：

定义文件上传方的应用主类和FeignClient，假设服务提供方的服务名为 eureka-feign-upload-server

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class Application {
public static void main(String[] args) {
new SpringApplicationBuilder(Application.class).web(true).run(args);
}
}
@FeignClient(value = "upload-server", configuration = UploadService.MultipartSupportConfig.class)
public interface UploadService {
@PostMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
String handleFileUpload(@RequestPart(value = "file") MultipartFile file);
@Configuration
class MultipartSupportConfig {
@Bean
public Encoder feignFormEncoder() {
return new SpringFormEncoder();
}
}
}

在启动了服务提供方之后，尝试在服务消费方编写测试用例来通过上面定义的Feign客户端来传文件，比如：

@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class UploadTester {
@Autowired
private UploadService uploadService;
@Test
@SneakyThrows
public void testHandleFileUpload() {
File file = new File("upload.txt");
DiskFileItem fileItem = (DiskFileItem) new DiskFileItemFactory().createItem("file",
MediaType.TEXT_PLAIN_VALUE, true, file.getName());
try (InputStream input = new FileInputStream(file); OutputStream os = fileItem.getOutputStream()) {
IOUtils.copy(input, os);
} catch (Exception e) {
throw new IllegalArgumentException("Invalid file: " + e, e);
}
MultipartFile multi = new CommonsMultipartFile(fileItem);
log.info(uploadService.handleFileUpload(multi));
}
}

读者可以根据喜好选择下面的两个仓库中查看 eureka-feign-upload-server和 eureka-feign-upload-client两个项目：

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