/** Copyright (c) 1997-1999 Bill Venners. All rights reserved.** Source code file from the book "Inside the Java 2 Virtual Machine,"* by Bill Venners, published by McGraw-Hill, 1999, ISBN: 0-07-135093-4. ** This source file may not be copied, modified, or redistributed* EXCEPT as allowed by the following statements: You may freely use* this file for your own work, including modifications and distribution* in compiled (class files, native executable, etc.) form only. You may* not copy and distribute this file. You may not remove this copyright* notice. You may not distribute modified versions of this source file.* You may not use this file in printed media without the express* permission of Bill Venners. ** BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE* SUITABILITY OF THIS SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS* FOR PARTICULAR PURPOSE, OR NON-INFRINGEMENT. BILL VENNERS SHALL NOT* BE LIABLE FOR ANY DAMAGES SUFFERED BY A LICENSEE AS A RESULT OF* USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.*/// On CD-ROM in file// security/ex2/com/artima/security/friend/Friend.javapackage com.artima.security.friend;import com.artima.security.doer.Doer;import java.security.AccessController;import java.security.PrivilegedAction;public class Friend implements Doer {    private Doer next;    private boolean direct;    public Friend(Doer next, boolean direct) {        this.next = next;        this.direct = direct;    }    public void doYourThing() {        if (direct) {            next.doYourThing();        }        else {            AccessController.doPrivileged(                new PrivilegedAction() {                    public Object run() {                        next.doYourThing();                        return null;                    }                }            );        }    }}