Should I close the servlet outputstream? [duplicate]

Question

Possible Duplicate:
Should one call .close() on HttpServletResponse.getOutputStream()/.getWriter()?

Am I responsible for closing the HttpServletResponse.getOutputStream() (or the getWriter() or even the inputstream) or should I leave it to the container ?

protected void doGet(HttpServletRequest request, HttpServletResponse response) 
   throws ServletException, IOException {
    OutputStream o = response.getOutputStream();
    ... 
    o.close(); //yes/no ?
}

Suzansuzann

Answer 1

You indeed don't need to do so.

Thumb rule: if you didn't create/open it yourself using new SomeOutputStream(), then you don't need to close it yourself. If it was for example a new FileOutputStream("c:/foo.txt"), then you obviously need to close it yourself.

Reasons that some people still do it are just to ensure that nothing more will be written to the response body. If it would ever happen, then this will cause an IllegalStateException in the appserver logs, but this wouldn't affect the client, so the client still gets the proper response. This is also an easier debug to spot the potential problems in the request-response chain which you wouldn't see at first glance. For example, something else is appending more data to the response body somewhere further down in the chain.

Another reason which you see among starters is that they just wanted to prevent that more data is written to the response body. You see this often when JSP incorrectly plays a role in the response. They just ignore the IllegalStateExceptions in the logs. Needless to say that this particular purpose is bad.

Lemay

You may want to close the stream if you have opened another InputStream to wrap it because the container will not have visibility of the wrapping stream, which may contain uncommitted bytes. Ideally you would just flush() the wrapping stream, if it's something like a BufferedOutputStream, but I discovered when using CipherOutputStream that this class doesn't fully write the data (I believe with good reason in this case). In this situation it was necessary to call close() for the client to get a correct response. – Ileus

Answer 2

No you don't need to close it. If you do you basically end the response to the client. After closing the stream you cannot send anything else to the client until the next request. You didn't open the stream, so you don't have to close it.

Messmate