A
WildcardPermission is a very flexible permission construct supporting multiple levels of permission matching. However, most people will probably follow some standard conventions as explained below.
Simple Usage
In the simplest form,
WildcardPermission can be used as a simple permission string. You could grant a user an "editNewsletter" permission and then check to see if the user has the editNewsletter permission by calling
subject.isPermitted("editNewsletter") This is (mostly) equivalent to
subject.isPermitted( new WildcardPermission("editNewsletter") ) but more on that later.
The simple permission string may work for simple applications, but it requires you to have permissions like
"viewNewsletter",
"deleteNewsletter",
"createNewsletter", etc. You can also grant a user
"*" permissions using the wildcard character (giving this class its name), which means they have
all permissions. But using this approach there's no way to just say a user has "all newsletter permissions".
For this reason,
WildcardPermission supports multiple
levels of permissioning.
Multiple Levels
WildcardPermission also supports the concept of multiple
levels. For example, you could restructure the previous simple example by granting a user the permission
"newsletter:edit". The colon in this example is a special character used by the
WildcardPermission that delimits the next token in the permission.
In this example, the first token is the
domain that is being operated on and the second token is the
action being performed. Each level can contain multiple values. So you could simply grant a user the permission
"newsletter:view,edit,create" which gives them access to perform
view,
edit, and
create actions in the
newsletter domain. Then you could check to see if the user has the
"newsletter:create" permission by calling
subject.isPermitted("newsletter:create") (which would return true).
In addition to granting multiple permissions via a single string, you can grant all permission for a particular level. So if you wanted to grant a user all actions in the
newsletter domain, you could simply give them
"newsletter:*". Now, any permission check for
"newsletter:XXX" will return
true. It is also possible to use the wildcard token at the domain level (or both): so you could grant a user the
"view" action across all domains
"*:view".
Instance-level Access Control
Another common usage of the
WildcardPermission is to model instance-level Access Control Lists. In this scenario you use three tokens - the first is the
domain, the second is the
action, and the third is the
instance you are acting on.
So for example you could grant a user
"newsletter:edit:12,13,18". In this example, assume that the third token is the system's ID of the newsletter. That would allow the user to edit newsletters
12,
13, and
18. This is an extremely powerful way to express permissions, since you can now say things like
"newsletter:*:13" (grant a user all actions for newsletter
13),
"newsletter:view,create,edit:*" (allow the user to
view,
create, or
edit any newsletter), or
"newsletter:*:* (allow the user to perform
any action on
any newsletter).
To perform checks against these instance-level permissions, the application should include the instance ID in the permission check like so:
subject.isPermitted( "newsletter:edit:13" ) There is no limit to the number of tokens that can be used, so it is up to your imagination in terms of ways that this could be used in your application. However, the Shiro team likes to standardize some common usages shown above to help people get started and provide consistency in the Shiro community.
@author Jeremy Haile
@author Les Hazlewood
@author Dain Sundstrom
@since 0.9