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

<dependency>
  <groupId>com.netflix.feign</groupId>
  <artifactId>feign-core</artifactId>
  <version>8.17.0</version>
</dependency>
<dependency>
  <groupId>com.netflix.feign</groupId>
  <artifactId>feign-jackson</artifactId>
  <version>8.17.0</version>
</dependency>
<dependency>
  <groupId>com.netflix.feign</groupId>
  <artifactId>feign-slf4j</artifactId>
  <version>8.17.0</version>
</dependency>

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;

/**
 * @author lxl
 */
public class FeignEncoder implements Encoder {

  private final List<HttpMessageConverter<?>> 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<String, ?>) object, template);
    } else {
      encodeRequest(object, jsonHeaders, template);
    }
  }

  private void encodeMultipartFormRequest(Map<String, ?> formMap, RequestTemplate template) throws EncodeException {
    if (CollectionUtils.isEmpty(formMap)) {
      throw new EncodeException("参数不能为空.");
    }
    LinkedMultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
    for (Entry<String, ?> 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());
  }

  /**
   * 设置头
   * @param file
   * @return
   */
  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);
    }
  }

  /**
   * 映射
   * @param map
   * @param name
   * @param files
   */
  private void encodeMultipartFiles(LinkedMultiValueMap<String, Object> map, String name, List<? extends MultipartFile> 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);
    }
  }

  /**
   * {@link HttpEntity} {@code Content-type}
   * {@code application/json}
   *
   * @param o
   * @return
   */
  private HttpEntity<?> encodeJsonObject(Object o) {
    HttpHeaders jsonPartHeaders = new HttpHeaders();
    jsonPartHeaders.setContentType(MediaType.APPLICATION_JSON);
    return new HttpEntity<>(o, jsonPartHeaders);
  }

  /**
   * {@link org.springframework.web.client.RestTemplate}
   *
   * @param value
   * @param requestHeaders
   * @param template
   * @throws EncodeException
   */
  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<Object>) messageConverter).write(
              value, requestContentType, dummyRequest);
          break;
        }
      }
    } catch (IOException ex) {
      throw new EncodeException("Cannot encode request.", ex);
    }
    HttpHeaders headers = dummyRequest.getHeaders();
    if (headers != null) {
      for (Entry<String, List<String>> entry : headers.entrySet()) {
        template.header(entry.getKey(), entry.getValue());
      }
    }
    /*
    使用bytearray方式传输
     */
    template.body(outputStream.toByteArray(), UTF_8);
  }

  /**
   * {@link org.springframework.http.HttpOutputMessage}
   * {@link org.springframework.http.converter.HttpMessageConverter}
   */
  private class HttpOutputMessageImpl implements HttpOutputMessage {

    private final OutputStream body;
    private final HttpHeaders headers;

    public HttpOutputMessageImpl(OutputStream body, HttpHeaders headers) {
      this.body = body;
      this.headers = headers;
    }

    @Override
    public OutputStream getBody() throws IOException {
      return body;
    }

    @Override
    public HttpHeaders getHeaders() {
      return headers;
    }

  }

  static boolean isFormRequest(Type type) {
    return MAP_STRING_WILDCARD.equals(type);
  }

  static class MultipartFileResource extends InputStreamResource {

    private final String filename;
    private final long size;

    public MultipartFileResource(String filename, long size, InputStream inputStream) {
      super(inputStream);
      this.size = size;
      this.filename = filename;
    }

    @Override
    public String getFilename() {
      return this.filename;
    }

    @Override
    public InputStream getInputStream() throws IOException, IllegalStateException {
      return super.getInputStream(); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public long contentLength() throws IOException {
      return size;
    }

  }

}

Feign调用接口

@RequestLine("POST /punish/imExcel")
ActionResult<List<String>> imPunishExcel(@Param("file") MultipartFile file, @Param("operatorId") Integer operatorId);

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。