Main.java Source code

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Here is the source code for Main.java

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//package com.java2s;
/*
 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

import java.security.*;
import java.lang.reflect.*;
import java.awt.*;

import java.awt.event.*;

import sun.awt.*;

public class Main {
    private static Field inputEvent_CanAccessSystemClipboard_Field = null;
    private static final String UntrustedClipboardAccess = "UNTRUSTED_CLIPBOARD_ACCESS_KEY";

    /**
     * checks the security permissions for accessing system clipboard
     *
     * for untrusted context (see isTrustedContext) checks the
     * permissions for the current event being handled
     *
     */
    public static boolean canAccessSystemClipboard() {
        boolean canAccess = false;
        if (!GraphicsEnvironment.isHeadless()) {
            SecurityManager sm = System.getSecurityManager();
            if (sm == null) {
                canAccess = true;
            } else {
                try {
                    sm.checkSystemClipboardAccess();
                    canAccess = true;
                } catch (SecurityException e) {
                }
                if (canAccess && !isTrustedContext()) {
                    canAccess = canCurrentEventAccessSystemClipboard(true);
                }
            }
        }
        return canAccess;
    }

    /**
     * see RFE 5012841 [Per AppContect security permissions] for the
     * details
     *
     */
    private static boolean isTrustedContext() {
        return (System.getSecurityManager() == null)
                || (AppContext.getAppContext().get(UntrustedClipboardAccess) == null);
    }

    /**
     * Returns true if EventQueue.getCurrentEvent() has the permissions to
     * access the system clipboard
     */
    public static boolean canCurrentEventAccessSystemClipboard() {
        return isTrustedContext() || canCurrentEventAccessSystemClipboard(false);
    }

    /**
     * Returns true if EventQueue.getCurrentEvent() has the permissions to
     * access the system clipboard and if it is allowed gesture (if
     * checkGesture true)
     *
     * @param checkGesture boolean
     */
    private static boolean canCurrentEventAccessSystemClipboard(boolean checkGesture) {
        AWTEvent event = EventQueue.getCurrentEvent();
        return canEventAccessSystemClipboard(event, checkGesture);
    }

    /**
     * Returns true if the given event has permissions to access the
     * system clipboard
     *
     * @param e AWTEvent to check
     */
    public static boolean canEventAccessSystemClipboard(AWTEvent e) {
        return isTrustedContext() || canEventAccessSystemClipboard(e, false);
    }

    /**
     * Returns true if e has the permissions to
     * access the system clipboard and if it is allowed gesture (if
     * checkGesture is true)
     *
     * @param e AWTEvent to check
     * @param checkGesture boolean
     */
    private static boolean canEventAccessSystemClipboard(AWTEvent e, boolean checkGesture) {
        if (EventQueue.isDispatchThread()) {
            /*
             * Checking event permissions makes sense only for event
             * dispathing thread
             */
            if (e instanceof InputEvent && (!checkGesture || isAccessClipboardGesture((InputEvent) e))) {
                return inputEvent_canAccessSystemClipboard((InputEvent) e);
            } else {
                return false;
            }
        } else {
            return true;
        }
    }

    /**
     * Returns true if the given event is corrent gesture for
     * accessing clipboard
     *
     * @param ie InputEvent to check
     */

    private static boolean isAccessClipboardGesture(InputEvent ie) {
        boolean allowedGesture = false;
        if (ie instanceof KeyEvent) { //we can validate only keyboard gestures
            KeyEvent ke = (KeyEvent) ie;
            int keyCode = ke.getKeyCode();
            int keyModifiers = ke.getModifiers();
            switch (keyCode) {
            case KeyEvent.VK_C:
            case KeyEvent.VK_V:
            case KeyEvent.VK_X:
                allowedGesture = (keyModifiers == InputEvent.CTRL_MASK);
                break;
            case KeyEvent.VK_INSERT:
                allowedGesture = (keyModifiers == InputEvent.CTRL_MASK || keyModifiers == InputEvent.SHIFT_MASK);
                break;
            case KeyEvent.VK_COPY:
            case KeyEvent.VK_PASTE:
            case KeyEvent.VK_CUT:
                allowedGesture = true;
                break;
            case KeyEvent.VK_DELETE:
                allowedGesture = (keyModifiers == InputEvent.SHIFT_MASK);
                break;
            }
        }
        return allowedGesture;
    }

    /**
     * returns canAccessSystemClipboard field from InputEvent
     *
     * @param ie InputEvent to get the field from
     */
    private static synchronized boolean inputEvent_canAccessSystemClipboard(InputEvent ie) {
        if (inputEvent_CanAccessSystemClipboard_Field == null) {
            inputEvent_CanAccessSystemClipboard_Field = AccessController
                    .doPrivileged(new java.security.PrivilegedAction<Field>() {
                        public Field run() {
                            try {
                                Field field = InputEvent.class.getDeclaredField("canAccessSystemClipboard");
                                field.setAccessible(true);
                                return field;
                            } catch (SecurityException e) {
                            } catch (NoSuchFieldException e) {
                            }
                            return null;
                        }
                    });
        }
        if (inputEvent_CanAccessSystemClipboard_Field == null) {
            return false;
        }
        boolean ret = false;
        try {
            ret = inputEvent_CanAccessSystemClipboard_Field.getBoolean(ie);
        } catch (IllegalAccessException e) {
        }
        return ret;
    }
}