Why doesn't Java request new versions of jar files several times?

Question

Every time we update our Java application (Java client and Java server), we have problems that some clients encounter. 1% - 2% does not download new jar files. This happens with the help of applets, as well as with Java Web Start. If you clear Java-Cache, everything works correctly.

Any idea why Java doesn't check for new jar files every time it starts?

Answer 1

This may be problematic for a solution, but there is a simple workaround for this. Instead of relying on the correct cache update, just make sure the JAR file names include the version / build number of the application. JAR files for the new version of the applet will work efficiently on a different URL (you also need to change the boot page).

Answer 2

I was there, and the only solution 100% guaranteed to work is to have a different path / URL for your resources (banks, images, etc.). No one can guarantee that there can be no errors in the caching mechanism (if you look in the JDK changes list every 2-3 releases, there is something related to the caching mechanism of the boxes).

So go with this (just add the last modified time as a line at the end of the jar url) and you won't have a problem:

Ex: http: //myserver/applet/codebase/your_jar.jar? V = 2487387543434 , and the next version will be http: //myserver/applet/codebase/your_jar.jar? V = 343438534545455 <- this is the last modified jar time.