Feign實現跨服務文件上傳下載

     臨近年關，本來想做完本地存儲的這個需求，再完成另一個需求，就可以溜之大吉的了。想不到突然老大說要整合一下你現在做的服務，給外部服務調用你服務的上傳下載接口。然後……

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好了，說回跨服務的文件上傳下載操作。

1.跨服務文件上傳，目前feign不支持調用文件上傳接口，需要自行配置來滿足feign的調用方式

①首先需要在pom文件裏添加feign依賴

  <dependency>    
    <groupId>io.github.openfeign.form</groupId>    
    <artifactId>feign-form-spring</artifactId>    
    <version>3.2.2</version>    
  </dependency>    
  <dependency>    
      <groupId>io.github.openfeign.form</groupId>    
      <artifactId>feign-form</artifactId>    
      <version>3.2.2</version>    
  </dependency>  

②上傳的接口

@FeignClient(value = "fdn-storage", configuration = {FileFeignConfig.class})
public interface FileClient {

    String PREFIX_PATH = "/oss/files";
    /**
     * 上傳存儲文件
     * @param file
     * @return
     * @throws IOException
     */
    @PostMapping(value = PREFIX_PATH + "/",  consumes = MULTIPART_FORM_DATA_VALUE)
    FeignResult<FileEntity>  save(@RequestPart(value = "file") MultipartFile file) throws IOException;
 }

③添加配置來滿足feign的調用

@Configuration
public class FileFeignConfig {
    @Autowired
    private ObjectFactory<HttpMessageConverters> messageConverters;

    @Bean
    @Primary
    @Scope("prototype")
    public Encoder feignEncoder() {
        return new SpringFormEncoder(new SpringEncoder(messageConverters));
    }

    @Bean
    public feign.Logger.Level multipartLoggerLevel() {
        return feign.Logger.Level.FULL;
    }
}

④外部服務的controller層調用

public class TestController extends BaseRestController {
    @Autowired
    FileClient client;
    /**
     * 上傳文件
     **/
    @PostMapping(value = "/" , consumes = MULTIPART_FORM_DATA_VALUE)
    public FileEntity save(@RequestPart(value = "file") MultipartFile file) throws IOException {
        FileEntity fileEntity = client.save(file).getData();
        return fileEntity;
    }
}    

到此位置就可以上傳成功了

2.跨服務的文件下載

①下載的接口（也是寫在public interface FileClient），是用feign.Response來作爲返回值的

    /**
     * 下載文件
     * @param id
     * @return
     * @throws IOException
     */
    @GetMapping(value = PREFIX_PATH + "/{id}/data")
    Response download(@PathVariable("id") String id) throws IOException;

②外部服務的controller層調用

 	/**
     *由id下載存儲的文件
     */
    @GetMapping(value = "/{id}/data")
    public void downloadFile(@PathVariable String id, HttpServletResponse servletResponse) throws IOException {
      Response response = client.download(id);
        Response.Body body = response.body();
        for(Object key : response.headers().keySet()){
            List<String> kList = (List)response.headers().get(key);
            for(String val : kList){
                servletResponse.setHeader(StringUtils.toString(key), val);
            }
        }
        try(InputStream inputStream = body.asInputStream();
            OutputStream outputStream = servletResponse.getOutputStream()
        ){
            byte[] b = new byte[inputStream.available()];
            inputStream.read(b);
            outputStream.write(b);
            outputStream.flush();
        }catch (IOException e){
            throw new RestException("IO流異常", e);
        }
    }

至此，下載文件完成。

快過年了，提前祝大家新年快樂！