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Should the StreamingOutput's OutputStream be closed by the implementing class?

The java-doc does not give any recommendations. I guess it just delegates to the underlying ServletOutputStream which means it should not be closed, but my guess might be wrong :) Also the javadoc makes a reference to the MessageBodyWriter interface where it's explicitly said that the output stream must not be closed.

https://docs.oracle.com/javaee/7/api/javax/ws/rs/core/StreamingOutput.html

Svetlin Zarev
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  • I don't think you should close it. There might be filters or interceptors downstream which might break if you close the output stream. – sinujohn Sep 19 '16 at 12:26

1 Answers1

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Being unable to find a definitive answer I took a look at jersey's source being the reference implementation. In Jersey the StreamingOutput is processed by a MessageBodyWriter by simply calling streamingOutput.write(os) [1] where os is the OutputStream passed to the MessageBodyWriter. That's good because its javadoc is quite clear that this OutputStream must not be closed.

To summarize: The OutputStream passed to the StreamingOutput must not be closed.

[1] https://github.com/jersey/jersey/blob/master/core-common/src/main/java/org/glassfish/jersey/message/internal/StreamingOutputProvider.java

Svetlin Zarev
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  • Excellent and very helpful Q&A. It is a shame this documentation is missing from the Javadocs for `interface StreamingOutput`! – kevinarpe May 30 '22 at 09:51