antville/helma
antville/helma
1
1
Fork 0
Code Issues 5 Pull requests 7 Projects Releases 5 Activity Actions

* Implement ETag based conditional GET for forwarded resources.

Browse source 
(ETag is based on last modified date and file size)
This commit is contained in:
hns 2006-06-03 07:13:06 +00:00
parent cab28b406a
commit 1c51121bdc
1 changed files with 29 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

34
src/helma/servlet/AbstractServletClient.java
View file

@ -493,22 +493,27 @@ public abstract class AbstractServletClient extends HttpServlet {
throw new IOException("Resource "+forward+" not found");
File file = new File(path);
// check last modified date.
// date headers don't do milliseconds, round to seconds
long lastModified = (file.lastModified() / 1000) * 1000;
long ifModifiedSince = req.getDateHeader("If-Modified-Since");
if (lastModified == ifModifiedSince) {
// calculate checksom on last modified date and content length.
byte[] checksum = getChecksum(file);
String etag = "\"" + new String(Base64.encode(checksum)) + "\"";
res.setHeader("ETag", etag);
String etagHeader = req.getHeader("If-None-Match");
if (etagHeader != null) {
StringTokenizer st = new StringTokenizer(etagHeader, ", \r\n");
while (st.hasMoreTokens()) {
if (etag.equals(st.nextToken())) {
res.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
return;
}
}
}
int length = (int) file.length();
res.setContentLength(length);
res.setDateHeader("Last-Modified", lastModified);
res.setContentType(hopres.getContentType());
InputStream in = cx.getResourceAsStream(forward);
if (in == null)
throw new IOException("Can't read "+path);
throw new IOException("Can't read " + path);
try {
OutputStream out = res.getOutputStream();
@ -533,6 +538,21 @@ public abstract class AbstractServletClient extends HttpServlet {
}
}
private byte[] getChecksum(File file) {
byte[] checksum = new byte[16];
long n = file.lastModified();
for (int i=0; i<8; i++) {
checksum[i] = (byte) (n);
n >>>= 8;
}
n = file.length();
for (int i=8; i<16; i++) {
checksum[i] = (byte) (n);
n >>>= 8;
}
return checksum;
}
/**
* Used to build the form value array when a multipart (file upload) form has
* multiple values for one form element name.