File upload endpoint need to close InputStream?

Question

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Path("/upload")
public String upload(@FormDataParam("file") InputStream inputStream) {
    ...
    inputStream.close(); // necessary?
}

For an API endpoint that accepts a file input, do we need to manually close the InputStream or does the framework do it for us?

I have checked the Jersey docs but could not find any information about it.

Looking for credible source or some way to validate it.

You should always close streams, unless you have solid evidence that the caller wants to do it. — user207421, Jun 04 '18 at 05:13
If you acquired the stream yes, here you did not acquire it, jersey did — sgdesmet, Nov 07 '18 at 12:57

score 2 · Accepted Answer · answered Jun 05 '18 at 08:48

2

It is your responsibility to close InputStream.

Jersey intrinsically cannot know when to close your stream.

answered Jun 05 '18 at 08:48

Hlib

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2

Is it? Jersey acquired the stream so jersey should close it, at least when the http request ends. When implementing a custom MessageBodyReader the [documentation](https://jersey.github.io/documentation/latest/message-body-workers.html#d0e6838) explicitly states "Do not close the entity input stream in your MessageBodyReader implementation. The stream will be automatically closed by Jersey runtime." – sgdesmet Nov 07 '18 at 12:55

score 1 · Answer 2 · answered Jun 05 '18 at 08:56

1) after you consumed the InputStream you can assume that it's safe to close it.

2) You can also register the InputStream with the Jersey ClosableService, according to its documentation it will close the InputStream for you. ClosableService

I hope that helps.

score 1 · Answer 3 · answered May 29 '19 at 15:11

I just wondered the same thing and tried it out in the debugger. Jersey does not close the stream for you.

I think the most elegant way is to use try-with-resources, which can take arbitrary expressions since Java 9 and calls close() for you.

@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Path("/upload")
public String upload(@FormDataParam("file") InputStream inputStream) {
...
try (inputStream) {
   //...
} catch (IOException e) {
   //...
}

File upload endpoint need to close InputStream?

3 Answers3

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