Jetty itself has no temporary directories, but each web application can be assigned a directory into which the war is unpacked, JSPs compiled on-the-fly etc.
The algorithm for determining a webapp's temporary directory location is as follows:
Try to use an explicit directory specifically for this webapp: Iff webapp.getTempDirectory() is set, use it. Do NOT delete it on jvm exit. Iff javax.servlet.context.tempdir context attribute is set for this webapp && exists && writeable, then use it. Do NOT delete on jvm exit. Create a directory based on global settings. The new directory will be called "Jetty_"host""port""context""+virtualhost : Iff $(jetty.home)/work exists create the directory there. Do NOT delete on jvm exit. Do NOT delete contents if dir already exists. Iff WEB-INF/work exists create the directory there. Do NOT delete on jvm exit. Do NOT delete contents if dir already exists. Else create dir in $(java.io.tmpdir). Set delete on jvm exit. Delete contents if dir already exists.
It is important to note that a temporary directory will have its contents deleted when the webapp is stopped unless either:
it is called "work" it pre-existed the deployment of the webapp
Once a tempory directory has been allocated, a File instance for it is set and retrievable as the javax.servlet.context.tempdir attribute of the web application.