ExtensionsResponseWrapper breaks Liskov substitution principle
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Key: TOMAHAWK-1442
URL: https://issues.apache.org/jira/browse/TOMAHAWK-1442
Project: MyFaces Tomahawk
Issue Type: Bug
Components: ExtensionsFilter
Affects Versions: 1.1.8
Reporter: Roy van Rijn
I've been working on a project which mixes JSF and Servlets. And in a
particulair Servlet I'm writing to the response (in some cases). Later on I
check if the response has been committed, but this doesn't work with the
ExtensionsResponseWrapper.
The problem is this:
HttpServletResponse response = (HttpServletResponse)
context.getExternalContext().getNativeResponse();
//Write the response:
response.getWriter().append(responseText.toString());
//Make sure its flushed (and thus closed/committed)
response.getWriter().flush();
response.flushBuffer();
log.debug(response.isCommitted);
----
This will print out: "false"
But it should be 'true' since we've written to the response and flushed the
writer and the buffer.
The reason is the internal delegate of the ExtensionsResponseWrapper. This is
used to write and read against, but the method isCommitted() is coupled to the
state of the internal delegate (in the ServletResponseWrapper).
My current work-around is:
/** For Tomahawk's ExtensionsFilter we need this: */
if(response instanceof ExtensionsResponseWrapper) {
((ExtensionsResponseWrapper)response).getDelegate().getWriter().append(responseText.toString());
((ExtensionsResponseWrapper)response).getDelegate().getWriter().flush();
((ExtensionsResponseWrapper)response).finishResponse();
} else {
response.getWriter().append(responseText.toString());
response.getWriter().flush();
response.flushBuffer();
}
This adds a new dependency to my framework which wasn't coupled to Tomahawk..
which I really don't want. But I can't seem to get it working otherwise.
The problem is that the flush should set the isCommitted() to true... and this
doesn't happen, breaking the Liskov substitution principle.
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