HistoryFilter is both a Handler and a
* Filter that keeps a record of all pages visited by a
* given session.
*
* The HistoryFilter can be used to
* make a user's session "mobile" as follows: A user's history
* is normally stored with the browser being used, on the user's machine.
* If the user runs a different browser or goes to a different machine, the
* user's history will not be there. Instead, the user can access the web
* via a proxy that keeps track of their history. No matter which browser
* the user chooses or machine the user is at, a server running with the
* HistoryFilter will automatically remember and be able to
* present the user's history.
*
* The history is kept with respect to a Session ID. *
* This filter uses the following configuration properties:
prefix
* session
* nosession
* admin
* HistoryFilter
* to store the history information for the current Session in the
* request properties
*
* filter
* Regexp pattern to match
* against the "Content-Type" of the result. Setting this also implies
* that the HistoryFilter will be invoked as a
* Filter and not a Handler. The default
* value is "", which indicates that the "Content-Type" is not
* examined and that this HistoryFilter will be invoked
* as a Handler.
*
* It is an error if the filter is specified but malformed.
*
* @param server
* The HTTP server.
*
* @param prefix
* The configuration property prefix.
*
* @return true if this filter initialized successfully,
* false otherwise.
*/
public boolean
init(Server server, String prefix)
{
this.prefix = prefix;
Properties props = server.props;
urlPrefix = props.getProperty(prefix + URL_PREFIX, urlPrefix);
session = props.getProperty(prefix + SESSION, session);
nosession = props.getProperty(prefix + NOSESSION, nosession);
admin = props.getProperty(prefix + ADMIN, admin);
if (admin.length() == 0) {
admin = null;
}
try {
String tmp = props.getProperty(prefix + FILTER, "");
if (tmp.length() > 0) {
filter = new Regexp(tmp);
}
} catch (IllegalArgumentException e) {
server.log(Server.LOG_DIAGNOSTIC, prefix, e.getMessage());
return false;
}
return true;
}
/**
* If the admin prefix is seen, store the history
* information associated with the session in the request properties.
*
* If invoked as a Handler and the URL matches the
* prefix, records this page's address in the history.
*
* @param request
* The Request object that represents the HTTP
* request.
*
* @return false, indicating that this respond
* method ran purely for its side effects.
*/
public boolean
respond(Request request)
{
if ((admin != null) && request.url.startsWith(admin)) {
StringBuffer sb = new StringBuffer();
Properties props = request.props;
Hashtable pages = getPages(request);
Enumeration keys = pages.keys();
for (int i = 0; keys.hasMoreElements(); i++) {
String url = (String) keys.nextElement();
PageInfo pi = (PageInfo) pages.get(url);
sb.append(i).append(' ');
String pfx = prefix + i;
props.put(pfx + ".url", pi.url);
props.put(pfx + ".first", HttpUtil.formatTime(pi.first));
props.put(pfx + ".last", HttpUtil.formatTime(pi.last));
props.put(pfx + ".count", Integer.toString(pi.count));
}
props.put(prefix + "pages", sb.toString());
} else if ((filter == null) && request.url.startsWith(urlPrefix)) {
/*
* If no Content-Type filter is present, it means that the
* HistoryFilter is being used as a Handler.
*/
recordUrl(request);
}
return false;
}
/**
* Called when invoked as a Filter. If the URL matches the
* prefix and the returned "Content-Type" matches the
* filter, records this page's address in the history.
*
* @param request
* The in-progress HTTP request.
*
* @param headers
* The MIME headers from the result.
*
* @return false indicating that this Filter
* does not want to modify the content.
*/
public boolean
shouldFilter(Request request, MimeHeaders headers)
{
try {
String type = headers.get("Content-Type");
if (request.url.startsWith(urlPrefix)
&& (filter.match(type) != null)) {
recordUrl(request);
}
} catch (Exception e) {
/* Ignore:
* No content-type
* Missing/malformed filter.
*/
}
return false;
}
/**
* Returns the original content, since this filter does not change
* content. Won't actually be invoked.
*/
public byte[]
filter(Request request, MimeHeaders headers, byte[] content)
{
return content;
}
private void
recordUrl(Request request)
{
Hashtable pages = getPages(request);
PageInfo pi = (PageInfo) pages.get(request.url);
if (pi == null) {
pi = new PageInfo(request.url);
pages.put(request.url, pi);
}
pi.count++;
pi.last = System.currentTimeMillis();
}
private Hashtable
getPages(Request request)
{
String id = request.props.getProperty(session, nosession);
return (Hashtable) SessionManager.getSession(id,
HistoryFilter.class, Hashtable.class);
}
/**
* Keep information about a visited URL
*/
static class PageInfo
implements Serializable
{
String url;
int count;
long first;
long last;
public
PageInfo(String url)
{
this.url = url;
first = System.currentTimeMillis();
}
}
}