OutputStream out = null;
// Select the appropriate content encoding based on the
// client's Accept-Encoding header. Choose GZIP if the header
// includes "gzip". Choose ZIP if the header includes "compress".
// Choose no compression otherwise. Make sure the Content-Encoding
// uses the "x-" prefix if and only if the Accept-Encoding does.
String encodings = req.getHeader("Accept-Encoding");
if (encodings != null && encodings.indexOf("gzip") != -1) {
// Go with GZIP
if (encodings.indexOf("x-gzip") != -1) {
res.setHeader("Content-Encoding", "x-gzip");
}
else {
res.setHeader("Content-Encoding", "gzip");
}
out = new GZIPOutputStream(res.getOutputStream());
}
else if (encodings != null && encodings.indexOf("compress") != -1) {
// Go with ZIP
if (encodings.indexOf("x-compress") != -1) {
res.setHeader("Content-Encoding", "x-compress");
}
else {
res.setHeader("Content-Encoding", "compress");
}
out = new ZipOutputStream(res.getOutputStream());
((ZipOutputStream)out).putNextEntry(new ZipEntry("dummy name"));
}
else {
// No compression
out = res.getOutputStream();
}
res.setHeader("Vary", "Accept-Encoding");
// Get the resource to view
URL url = null;
try {
url = ServletUtils.getResource(getServletContext(), req.getPathInfo());
}
catch (IOException e) {
res.sendError(
res.SC_NOT_FOUND,
"Extra path info must point to a valid resource to view: " +
e.getMessage());
}
// Connect to the resource
URLConnection con = url.openConnection();
con.connect();
// Get and set the type of the resource
String contentType = con.getContentType();
res.setContentType(contentType);
// Return the resource
try {
ServletUtils.returnURL(url, out);
}
catch (IOException e) {
res.sendError(res.SC_INTERNAL_SERVER_ERROR,
"Problem sending resource: " + e.getMessage());
}
// Write the compression trailer and close the output stream
out.close();
