Call a private method in Spring @PreAuthorize

Question

I am using Spring Security for permission checking on methods. I would like to call a private method to collect some data to send to hasPermission() method. Following is something I am trying to execute and I get SpelEvaluationException because Spring is looking for the localPrivateMethod in MethodSecurityExpressionRoot. Is there a way to achieve this? Thanks.

@PreAuthorize("hasPermission(new Object[]{#arg3, #localPrivateMethod(#arg1,#arg2)}, 'canDoThis')")  
public long publicMethod1(long arg1, long arg2, long arg3) {}

private String localPrivateMethod(long a1, long a2) {}

Answer 1

Private methods cannot be called, but you can refer to "this component" through this.:

@PreAuthorize("hasPermission(new Object[]{#arg3, /* HERE: */ this.localPublicMethod(#arg1,#arg2)}, 'canDoThis')")   
public long publicMethod1(long arg1, long arg2, long arg3)
{
}

public String localPublicMethod(long a1, long a2)
{
}

Answer 2

You will not be able to call a private method, but you will be able to call a method in another spring bean. In my app I have an @Component named permissionEvaluator. I then reference it in a @PreAuthorize like so:

@PreAuthorize("@permissionEvaluator.canViewImageSet( #imageSet, principal )")
@RequestMapping(value="/image", method=RequestMethod.GET )
public String getImage(
        @RequestParam(value="imageSet", required=false) ImageSet imageSet ) {
    // method body
}

PermissionEvaluatorImpl looks like this:

@Component(value="permissionEvaluator")
public class PermissionEvaluatorImpl implements PermissionEvaluator
{
    public PermissionEvaluatorImpl() {}

    /**
     * Determine if a user can view a given image.
     */
    public boolean canViewImageSet( ImageSet imageSet, UserDetailsAdapter user )
    {
        // code to see if they should view this image
    }
}

and PermissionEvaluator is my own interface with nothing special, just whatever methods I need to evaluate.