antville/helma
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* Implement both ETag and Last-Modified based conditional requests as some browsers

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(e.g. Safari) don't seem to support ETags for embedded images and stuff.
This commit is contained in:
hns 2006-08-09 10:24:31 +00:00
parent 9491159dbb
commit 16eca87022
1 changed files with 35 additions and 26 deletions
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61
src/helma/servlet/AbstractServletClient.java
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@ -490,22 +490,14 @@ public abstract class AbstractServletClient extends HttpServlet {
ServletContext cx = getServletConfig().getServletContext();
String path = cx.getRealPath(forward);
if (path == null)
throw new IOException("Resource "+forward+" not found");
throw new IOException("Resource " + forward + " not found");
File file = new File(path);
// 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;
}
}
// check if the client has an up-to-date copy so we can
// send a not-modified response
if (checkNotModified(file, req, res)) {
res.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
return;
}
int length = (int) file.length();
res.setContentLength(length);
@ -538,7 +530,10 @@ public abstract class AbstractServletClient extends HttpServlet {
}
}
private byte[] getChecksum(File file) {
private boolean checkNotModified(File file, HttpServletRequest req, HttpServletResponse res) {
// we do two rounds of conditional requests:
// first ETag based, then based on last modified date.
// calculate ETag checksum on last modified date and content length.
byte[] checksum = new byte[16];
long n = file.lastModified();
for (int i=0; i<8; i++) {
@ -550,7 +545,27 @@ public abstract class AbstractServletClient extends HttpServlet {
checksum[i] = (byte) (n);
n >>>= 8;
}
return checksum;
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())) {
return true;
}
}
}
// as a fallback, since some browsers don't support ETag based
// conditional GET for embedded images and stuff, 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) {
return true;
}
res.setDateHeader("Last-Modified", lastModified);
return false;
}
/**
@ -810,12 +825,7 @@ public abstract class AbstractServletClient extends HttpServlet {
if (protocol == null) {
return false;
}
if (protocol.endsWith("1.1")) {
return true;
}
return false;
return protocol.endsWith("1.1");
}
String getPathInfo(HttpServletRequest req)
@ -856,11 +866,10 @@ public abstract class AbstractServletClient extends HttpServlet {
}
/**
*
*
* @return ...
* Return servlet info
* @return the servlet info
*/
public String getServletInfo() {
return new String("Helma Servlet Client");
return "Helma Servlet Client";
}
}