• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 288
  • Last Modified:

How to know if a web page's last update time

Hi,

As noted above, I want to use Java to detect a web page's last update time via httpresponse, etc. I don't want to save the web page's contents and verify through the contents.

Thanks
0
wsyy
Asked:
wsyy
  • 3
  • 2
  • 2
  • +1
3 Solutions
 
objectsCommented:
check the Last-Modified value in the http response header
0
 
objectsCommented:
theres some code here that shows how to access the headers

http://helpdesk.objects.com.au/java/how-do-i-get-the-cookies-from-a-http-connection

If you just want the one value you can use

long lastModified = urlconnection.getLastModified();
0
 
wsyyAuthor Commented:
what if the header doesn't include the info? are there any other ways?
0
Get your Conversational Ransomware Defense e‑book

This e-book gives you an insight into the ransomware threat and reviews the fundamentals of top-notch ransomware preparedness and recovery. To help you protect yourself and your organization. The initial infection may be inevitable, so the best protection is to be fully prepared.

 
objectsCommented:
not unless they including it some other custom header
0
 
calboronsterCommented:
As a caution comment, not a very good idea to detect browser time and take action because :

1. Browser time can be tampered by the end user.
2. There could be a real time difference between server and the client.

The best way is for the server to set a session token in response which can then be traced back in next responses and compared each time by the server for last access time (for that session token).
0
 
CEHJCommented:
You can generally only do that if the web page is a static file unless the site has some other means of announcing it.

It's worth checking if the If-Modified-Since header is set though - some sites implement this
0
 
wsyyAuthor Commented:
calboronster:

My crawling application wants to detect the changes of a web page ever since last crawl. The solution you provided seems that a good check can be done only on the server side which may not help my case.

Thanks
0
 
CEHJCommented:
>>The solution you provided seems that a good check can be done only on the server side which may not help my case.

I wonder why you accepted it then?
0

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

  • 3
  • 2
  • 2
  • +1
Tackle projects and never again get stuck behind a technical roadblock.
Join Now