关闭传递给MultipartFormDataOutput的流

问题描述

Resteasy docs没有解释谁负责关闭传递给MultipartFormDataOutput的流。让我们考虑以下示例：

WebTarget target = ClientBuilder.newClient().target("url");
MultipartFormDataOutput formData = new MultipartFormDataOutput();
FileInputStream fis1 = new FileInputStream(new File("/path/to/image1"));
FileInputStream fis2 = new FileInputStream(new File("/path/to/image2"));
formData.addFormData("image",fis1,MediaType.APPLICATION_OCTET_STREAM_TYPE);
formData.addFormData("image",fis2,MediaType.APPLICATION_OCTET_STREAM_TYPE);
Entity<MultipartFormDataOutput> entity = Entity.entity(formData,MediaType.MULTIPART_FORM_DATA);
Response response = target.request().post(entity);

fis1和fis2会被安逸的人关闭吗，还是用户应该注意关闭这些流？

解决方法

我建议使用try-with-resource以确保它们将被关闭。

WebTarget target = ClientBuilder.newClient().target("url");
MultipartFormDataOutput formData = new MultipartFormDataOutput();

try(FileInputStream fis1 = new FileInputStream(new File("/path/to/image1")));
    FileInputStream fis2 = new FileInputStream(new File("/path/to/image2")))
{
  formData.addFormData("image",fis1,MediaType.APPLICATION_OCTET_STREAM_TYPE);
  formData.addFormData("image",fis2,MediaType.APPLICATION_OCTET_STREAM_TYPE);
  Entity<MultipartFormDataOutput> entity = Entity.entity(formData,MediaType.MULTIPART_FORM_DATA);
  Response response = target.request().post(entity);
}

,

所以我自己可以回答我的问题，希望有人能从中受益。

Resteasy将关闭传递的流。就我而言，InputStreamProvider将负责关闭FileInputStream。

     public void writeTo(InputStream inputStream,Class<?> type,Type genericType,Annotation[] annotations,MediaType mediaType,MultivaluedMap<String,Object> httpHeaders,OutputStream entityStream) throws IOException
   {
           LogMessages.LOGGER.debugf("Provider : %s,Method : writeTo",getClass().getName());
       try
       {
           int c = inputStream.read();
           if (c == -1)
           {
               httpHeaders.putSingle(HttpHeaderNames.CONTENT_LENGTH,Integer.toString(0));
               entityStream.write(new byte[0]); // fix RESTEASY-204
               return;
           }
           else
               entityStream.write(c);
         ProviderHelper.writeTo(inputStream,entityStream);
       }
       finally
       {
         inputStream.close();
       }
   }