securitysupport.java

来自「JAVA的一些源码 JAVA2 STANDARD EDITION DEVELO」· Java 代码 · 共 155 行

/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The name "Apache Software Foundation" must not be used to endorse or
 *    promote products derived from this software without prior written
 *    permission. For written permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999-2002, Sun Microsystems,
 * Inc., http://www.sun.com.  For more information on the Apache Software
 * Foundation, please see <http://www.apache.org/>.
 */

package com.sun.org.apache.xerces.internal.dom;

import java.io.*;

/**
 * This class is duplicated for each JAXP subpackage so keep it in sync.
 * It is package private and therefore is not exposed as part of the JAXP
 * API.
 *
 * Base class with security related methods that work on JDK 1.1.
 */
class SecuritySupport {

    /*
     * Make this of type Object so that the verifier won't try to
     * prove its type, thus possibly trying to load the SecuritySupport12
     * class.
     */
    private static final Object securitySupport;

    static {
	SecuritySupport ss = null;
	try {
	    Class c = Class.forName("java.security.AccessController");
	    // if that worked, we're on 1.2.
	    /*
	    // don't reference the class explicitly so it doesn't
	    // get dragged in accidentally.
	    c = Class.forName("javax.mail.SecuritySupport12");
	    Constructor cons = c.getConstructor(new Class[] { });
	    ss = (SecuritySupport)cons.newInstance(new Object[] { });
	    */
	    /*
	     * Unfortunately, we can't load the class using reflection
	     * because the class is package private.  And the class has
	     * to be package private so the APIs aren't exposed to other
	     * code that could use them to circumvent security.  Thus,
	     * we accept the risk that the direct reference might fail
	     * on some JDK 1.1 JVMs, even though we would never execute
	     * this code in such a case.  Sigh...
	     */
	    ss = new SecuritySupport12();
	} catch (Exception ex) {
	    // ignore it
	} finally {
	    if (ss == null)
		ss = new SecuritySupport();
	    securitySupport = ss;
	}
    }

    /**
     * Return an appropriate instance of this class, depending on whether
     * we're on a JDK 1.1 or J2SE 1.2 (or later) system.
     */
    static SecuritySupport getInstance() {
	return (SecuritySupport)securitySupport;
    }

    ClassLoader getContextClassLoader() {
	return null;
    }

    ClassLoader getSystemClassLoader() {
        return null;
    }

    ClassLoader getParentClassLoader(ClassLoader cl) {
        return null;
    }

    String getSystemProperty(String propName) {
        return System.getProperty(propName);
    }

    FileInputStream getFileInputStream(File file)
        throws FileNotFoundException
    {
        return new FileInputStream(file);
    }

    InputStream getResourceAsStream(ClassLoader cl, String name) {
        InputStream ris;
        if (cl == null) {
            ris = ClassLoader.getSystemResourceAsStream(name);
        } else {
            ris = cl.getResourceAsStream(name);
        }
        return ris;
    }

    boolean getFileExists(File f) {
        return f.exists();
    }

    long getLastModified(File f) {
        return f.lastModified();
    }
}