sampleaction.java

本书以大量精简的实例介绍了Java安全性编程方面的概念和技术

/*
 * @(#)SampleAction.java	1.4 00/01/11
 *
 * Copyright 2000-2002 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met:
 * 
 * -Redistributions of source code must retain the above copyright  
 * notice, this  list of conditions and the following disclaimer.
 * 
 * -Redistribution in binary form must reproduct the above copyright 
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 * the documentation and/or other materials provided with the 
 * distribution.
 * 
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 * contributors may be used to endorse or promote products derived 
 * from this software without specific prior written permission.
 * 
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 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
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 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY 
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 */

package sample;

import java.io.File;
import java.security.PrivilegedAction;

/**
 * <p> This is a Sample PrivilegedAction implementation, designed to be
 * used with the Sample application.
 *
 * @version 1.4, 01/11/00
 */
public class SampleAction implements PrivilegedAction {

    /**
     * <p> This Sample PrivilegedAction performs the following operations:
     * <ul>
     * <li> Access the System property, <i>java.home</i>
     * <li> Access the System property, <i>user.home</i>
     * <li> Access the file, <i>foo.txt</i>
     * </ul>
     *
     * @return <code>null</code> in all cases.
     *
     * @exception SecurityException if the caller does not have permission
     *		to perform the operations listed above.
     */
    public Object run() {
	System.out.println("\nYour java.home property: "
			    +System.getProperty("java.home"));

	System.out.println("\nYour user.home property: "
			    +System.getProperty("user.home"));

	File f = new File("foo.txt");
	System.out.print("\nfoo.txt does ");
	if (!f.exists())
	    System.out.print("not ");
	System.out.println("exist in the current working directory.");
	return null;
    }
}