使用Feign实现微服务间文件传输

在很多时候我们会遇到微服务之间文件传输，很多时候我们可以通过序列化等方式解决（如图片等）。

最近项目中有个excel上传，以及多媒体文件上传，直接报错。

也试了2种解决方式，都不可行。

1.写一个文件Encoder解析器，会出现其他的rest请求出现encoder错误

2.springcloud feign有一个规范，不可以传输2个对象，可以是一个对象带几个参数方式。

那么我们现在需要一种方式，不配置全局的解析器，而是通过Feign Builder 去管理上传文件，这种方式管理起来也较为方便。

引用包

  com.netflix.feign
  feign-core
  8.17.0


  com.netflix.feign
  feign-jackson
  8.17.0


  com.netflix.feign
  feign-slf4j
  8.17.0

调用方式 

@ApiOperation(value = "上传Excel", notes = "上传Excel")
@RequestMapping(value = "/imExcel", method = RequestMethod.POST, produces = request_headers)
public ActionResult imExcel(@RequestBody MultipartFile file,@RequestParam("operatorId") Integer operatorId){
 
  if(file == null || file.isEmpty()|| operatorId==null)
    return new ActionResult<>(ResultType.BAD_REQUEST,"文件与操作用户ID都不能为空");
  String fileName = file.getOriginalFilename();
  if (!fileName.matches("^.+\.(?i)(xls)$") && !fileName.matches("^.+\.(?i)(xlsx)$")) {
    return new ActionResult<>(ResultType.BAD_REQUEST,"上传文件格式错误，请上传后缀为.xls或.xlsx的文件");
  }
  Feign.Builder encoder = Feign.builder()
      .decoder(new JacksonDecoder())
      .encoder(new FeignEncoder());
  FileUpload complainFileUpload = encoder.target(FileUpload.class,LABEL_URL);
  return complainFileUpload.imComplainExcel(file,operatorId);
 
}

文件Encode

import feign.RequestTemplate;
import feign.codec.EncodeException;
import feign.codec.Encoder;
import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.util.CollectionUtils;
import org.springframework.util.linkedMultiValueMap;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.multipart.MultipartFile;
 
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Type;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
 

public class FeignEncoder implements Encoder {
 
 
  private final List> converters = new RestTemplate().getMessageConverters();
  private final HttpHeaders multipartHeaders = new HttpHeaders();
  private final HttpHeaders jsonHeaders = new HttpHeaders();
 
  public static final Charset UTF_8 = Charset.forName("UTF-8");
 
  public FeignEncoder() {
    multipartHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);
    jsonHeaders.setContentType(MediaType.APPLICATION_JSON);
  }
 
 
  @Override
  public void encode(Object object, Type bodyType, RequestTemplate template) throws EncodeException {
    if (isFormRequest(bodyType)) {
      encodeMultipartFormRequest((Map) object, template);
    } else {
      encodeRequest(object, jsonHeaders, template);
    }
  }
 
 
  private void encodeMultipartFormRequest(Map formMap, RequestTemplate template) throws EncodeException {
    if (CollectionUtils.isEmpty(formMap)) {
      throw new EncodeException("参数不能为空.");
    }
    linkedMultiValueMap map = new linkedMultiValueMap<>();
    for (Entry entry : formMap.entrySet()) {
      Object value = entry.getValue();
      if (isMultipartFile(value)) {
 map.add(entry.getKey(), encodeMultipartFile((MultipartFile) value));
      } else if (isMultipartFileArray(value)) {
 encodeMultipartFiles(map, entry.getKey(), Arrays.asList((MultipartFile[]) value));
      } else {
 map.add(entry.getKey(), encodeJsonObject(value));
      }
    }
    encodeRequest(map, multipartHeaders, template);
  }
 
  private boolean isMultipartFile(Object object) {
    return object instanceof MultipartFile;
  }
 
  private boolean isMultipartFileArray(Object o) {
    return o != null && o.getClass().isArray() && MultipartFile.class.isAssignableFrom(o.getClass().getComponentType());
  }
 
  
  private HttpEntity encodeMultipartFile(MultipartFile file) {
    HttpHeaders filePartHeaders = new HttpHeaders();
    filePartHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
    try {
      Resource multipartFileResource = new MultipartFileResource(file.getOriginalFilename(), file.getSize(), file.getInputStream());
      return new HttpEntity<>(multipartFileResource, filePartHeaders);
    } catch (IOException ex) {
      throw new EncodeException("Cannot encode request.", ex);
    }
  }
 
  
  private void encodeMultipartFiles(linkedMultiValueMap map, String name, List files) {
    HttpHeaders filePartHeaders = new HttpHeaders();
    filePartHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
    try {
      for (MultipartFile file : files) {
 Resource multipartFileResource = new MultipartFileResource(file.getOriginalFilename(), file.getSize(), file.getInputStream());
 map.add(name, new HttpEntity<>(multipartFileResource, filePartHeaders));
      }
    } catch (IOException ex) {
      throw new EncodeException("Cannot encode request.", ex);
    }
  }
 
  
  private HttpEntity encodeJsonObject(Object o) {
    HttpHeaders jsonPartHeaders = new HttpHeaders();
    jsonPartHeaders.setContentType(MediaType.APPLICATION_JSON);
    return new HttpEntity<>(o, jsonPartHeaders);
  }
 
  
  private void encodeRequest(Object value, HttpHeaders requestHeaders, RequestTemplate template) throws EncodeException {
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    HttpOutputMessage dummyRequest = new HttpOutputMessageImpl(outputStream, requestHeaders);
    try {
      Class requestType = value.getClass();
      MediaType requestContentType = requestHeaders.getContentType();
      for (HttpMessageConverter messageConverter : converters) {
 if (messageConverter.canWrite(requestType, requestContentType)) {
   ((HttpMessageConverter