解决OpenFeign默认无法上传文件的问题

前言

　　最近在项目中使用OpenFeign时，发现其不支持文件上传功能。网上找了很多资料，最后找到feign-form和feign-form-spring的解决方案。但其默认只支持单文件上传，不支持多文件上传。解决办法为：重写Encoder类，详见三。

一、配置

1. 引入依赖

<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form-spring</artifactId>
    <version>3.3.0</version>
</dependency>

2. 在调用方增加配置

@Configuration
public class AdminWebMvcConfig implements WebMvcConfigurer {
    @Bean
    public Encoder feignFormEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
        return new SpringFormEncoder(new SpringEncoder(messageConverters));
    }
}

3. 调用方启动类配置

@EnableFeignClients(basePackages = {"com.xxx.xxx"})
@SpringCloudApplication
@Import({AdminWebMvcConfig.class})
public class WebAdminApplication {

    public static void main(String[] args) {
        SpringApplication.run(WebAdminApplication.class, args);
    }

}

二、单文件上传代码实现

• 服务调用方、接口和提供方，都使用@RequestPart注解
• 标记MediaType.MULTIPART_FORM_DATA_VALUE

1. 服务提供方Controller

@PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
@ResponseBody
public String upload(@RequestPart(value = "file") MultipartFile file) {

　　......
}

2. FeignClient接口

@FeignClient(name = "xxx")
public interface FileUploadApiClient {
　　/**
　　* 文件上传
　　*/
　　@PostMapping(value = "/oss/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
　　String upload(@RequestPart(value = "file") MultipartFile file);

}

3. 调用方Controller

@RestController
public class FileUploadManagerController {

　　@Autowired
　　private FileUploadApiClient fileUploadApiClient;

　　@PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
　　@ResponseBody
　　public String upload(@RequestPart(value = "file") MultipartFile file) {
　　　　return fileUploadApiClient.upload(file);
　　}
}

三、多文件上传实现

• 　只需修改下面两项，即可完美支持单文件和多文件上传功能

1. 新建FeignSpringFormEncoder类

import feign.RequestTemplate;
import feign.codec.EncodeException;
import feign.codec.Encoder;
import feign.form.ContentType;
import feign.form.FormEncoder;
import feign.form.MultipartFormContentProcessor;
import feign.form.spring.SpringManyMultipartFilesWriter;
import feign.form.spring.SpringSingleMultipartFileWriter;
import org.springframework.web.multipart.MultipartFile;

import java.lang.reflect.Type;
import java.util.Collections;
import java.util.Map;

public class FeignSpringFormEncoder extends FormEncoder {

    /**
     * Constructor with the default Feign's encoder as a delegate.
     */
    public FeignSpringFormEncoder() {
        this(new Default());
    }

    /**
     * Constructor with specified delegate encoder.
     *
     * @param delegate delegate encoder, if this encoder couldn't encode object.
     */
    public FeignSpringFormEncoder(Encoder delegate) {
        super(delegate);

        MultipartFormContentProcessor processor = (MultipartFormContentProcessor) getContentProcessor(ContentType.MULTIPART);
        processor.addWriter(new SpringSingleMultipartFileWriter());
        processor.addWriter(new SpringManyMultipartFilesWriter());
    }

    @Override
    public void encode(Object object, Type bodyType, RequestTemplate template) throws EncodeException {
        if (bodyType.equals(MultipartFile.class)) {
            MultipartFile file = (MultipartFile) object;
            Map data = Collections.singletonMap(file.getName(), object);
            super.encode(data, MAP_STRING_WILDCARD, template);
            return;
        } else if (bodyType.equals(MultipartFile[].class)) {
            MultipartFile[] file = (MultipartFile[]) object;
            if(file != null) {
                Map data = Collections.singletonMap(file.length == 0 ? "" : file[0].getName(), object);
                super.encode(data, MAP_STRING_WILDCARD, template);
                return;
            }
        }
        super.encode(object, bodyType, template);
    }
}

2. 修改AdminWebMvcConfig

@Configuration
public class AdminWebMvcConfig implements WebMvcConfigurer {

    @Bean
    public Encoder feignEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
        return new FeignSpringFormEncoder(new SpringEncoder(messageConverters));
    }
}

参考：https://blog.csdn.net/ytzzh0726/article/details/79467843