securitydomain.java

有关j2me的很好的例子可以研究一下

/*
 *  @(#)SecurityDomain.java	1.4 01/08/08
 * 
 *  Copyright (c) 2001 Sun Microsystems, Inc., 901 San Antonio Road,
 *  Palo Alto, CA 94303, U.S.A.  All Rights Reserved.
 *
 *  Sun Microsystems, Inc. has intellectual property rights relating
 *  to the technology embodied in this software.  In particular, and
 *  without limitation, these intellectual property rights may include
 *  one or more U.S. patents, foreign patents, or pending
 *  applications.  Sun, Sun Microsystems, the Sun logo, Java, KJava,
 *  and all Sun-based and Java-based marks are trademarks or
 *  registered trademarks of Sun Microsystems, Inc.  in the United
 *  States and other countries.
 *
 *  This software is distributed under licenses restricting its use,
 *  copying, distribution, and decompilation.  No part of this
 *  software may be reproduced in any form by any means without prior
 *  written authorization of Sun and its licensors, if any.
 *
 *  FEDERAL ACQUISITIONS:  Commercial Software -- Government Users
 *  Subject to Standard License Terms and Conditions
 */
package com.sun.midp.security;

/**
 * Contains methods to get various security state information of the currently
 * running MIDlet suite. It cannot be instantiated.
 */
public final class SecurityDomain {
    /** Name of the internal domain. */
    // according to the MExE spec the user of phone has full control.
    public static final String INTERNAL_DOMAIN_NAME = "user";

    /** Enables the first domain be constructed without a domain. */
    private static boolean firstCaller = true;

    /** Domain name. */
    private String name;


    /** Permitted actions. */
    private int actions[] = null;

    /**
     * Creates a security domain with a list of permitted actions or no list
     * to indicate all actions. The caller must be have permission for
     * <code>Actions.DEVICE_CORE_FUNCTION</code> or be the first caller of
     * the method for this instance of the VM.
     * @param securityDomain security domain of the caller, can be null for
     *                       the first caller
     * @param theName domain to create, can be null
     * @exception SecurityException if caller is not permitted to call this
     *            method
     */
    public SecurityDomain(SecurityDomain securityDomain, String theName) {
        // assume the JAM is the first caller
        if (firstCaller) {
            firstCaller = false;
        } else {
            securityDomain.checkIfPermitted(Actions.DEVICE_CORE_FUNCTION);
        }

        if (theName == null) {
            name = INTERNAL_DOMAIN_NAME;

            /* signal all actions by keeping the actions field null */
            return;
        }

        name = theName;
        actions = Actions.forDomain(name);
    }

    /**
     * Check to see the domain permitted to perform a specific action.
     *
     * @param action an action code
     * @exception SecurityException if the domain is not
     *            permitted to perform the specified action.
     */
    public void checkIfPermitted(int action) {
        if (actions == null) {
            /* totally trusted, all actions are permitted */
            return;
        }

        for (int i = 0; i < actions.length; i++) {
            if (actions[i] == action) {
                return;
            }
        }

        throw new SecurityException("Application not authorized " +
                                    "to access the restricted API");
    }

    /**
     * Gets the name of this security domain.
     *
     * @return name of this security domain
     */
    public String getName() {
        return name;
    }
}