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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.awt;

import java.io.File;
import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URI;
import java.net.URL;
import java.net.MalformedURLException;
import java.awt.AWTPermission;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.peer.DesktopPeer;
import sun.awt.SunToolkit;
import sun.awt.HeadlessToolkit;
import java.io.FilePermission;
import sun.security.util.SecurityConstants;

/**
 * The {@code Desktop} class allows a Java application to launch
 * associated applications registered on the native desktop to handle
 * a {@link java.net.URI} or a file.
 *
 * <p> Supported operations include:
 * <ul>
 * <li>launching the user-default browser to show a specified
 * URI;</li>
 * <li>launching the user-default mail client with an optional
 * {@code mailto} URI;</li>
 * <li>launching a registered application to open, edit or print a
 * specified file.</li>
 * </ul>
 *
 * <p> This class provides methods corresponding to these
 * operations. The methods look for the associated application
 * registered on the current platform, and launch it to handle a URI
 * or file. If there is no associated application or the associated
 * application fails to be launched, an exception is thrown.
 *
 * <p> An application is registered to a URI or file type; for
 * example, the {@code "sxi"} file extension is typically registered
 * to StarOffice. The mechanism of registering, accessing, and
 * launching the associated application is platform-dependent.
 *
 * <p> Each operation is an action type represented by the {@link
 * Desktop.Action} class.
 *
 * <p> Note: when some action is invoked and the associated
 * application is executed, it will be executed on the same system as
 * the one on which the Java application was launched.
 *
 * @since 1.6
 * @author Armin Chen
 * @author George Zhang
 */
public class Desktop {

 /**
 * Represents an action type. Each platform supports a different
 * set of actions. You may use the {@link Desktop#isSupported}
 * method to determine if the given action is supported by the
 * current platform.
 * @see java.awt.Desktop#isSupported(java.awt.Desktop.Action)
 * @since 1.6
 */
 public static enum Action {
 /**
 * Represents an "open" action.
 * @see Desktop#open(java.io.File)
 */
 OPEN,
 /**
 * Represents an "edit" action.
 * @see Desktop#edit(java.io.File)
 */
 EDIT,
 /**
 * Represents a "print" action.
 * @see Desktop#print(java.io.File)
 */
 PRINT,
 /**
 * Represents a "mail" action.
 * @see Desktop#mail()
 * @see Desktop#mail(java.net.URI)
 */
 MAIL,
 /**
 * Represents a "browse" action.
 * @see Desktop#browse(java.net.URI)
 */
 BROWSE
 };

 private DesktopPeer peer;

 /**
 * Suppresses default constructor for noninstantiability.
 */
 private Desktop() {
 peer = Toolkit.getDefaultToolkit().createDesktopPeer(this);
 }

 /**
 * Returns the <code>Desktop</code> instance of the current
 * browser context. On some platforms the Desktop API may not be
 * supported; use the {@link #isDesktopSupported} method to
 * determine if the current desktop is supported.
 * @return the Desktop instance of the current browser context
 * @throws HeadlessException if {@link
 * GraphicsEnvironment#isHeadless()} returns {@code true}
 * @throws UnsupportedOperationException if this class is not
 * supported on the current platform
 * @see #isDesktopSupported()
 * @see java.awt.GraphicsEnvironment#isHeadless
 */
 public static synchronized Desktop getDesktop(){
 if (GraphicsEnvironment.isHeadless()) throw new HeadlessException();
 if (!Desktop.isDesktopSupported()) {
 throw new UnsupportedOperationException("Desktop API is not " +
 "supported on the current platform");
 }

 sun.awt.AppContext context = sun.awt.AppContext.getAppContext();
 Desktop desktop = (Desktop)context.get(Desktop.class);

 if (desktop == null) {
 desktop = new Desktop();
 context.put(Desktop.class, desktop);
 }

 return desktop;
 }

 /**
 * Tests whether this class is supported on the current platform.
 * If it's supported, use {@link #getDesktop()} to retrieve an
 * instance.
 *
 * @return <code>true</code> if this class is supported on the
 * current platform; <code>false</code> otherwise
 * @see #getDesktop()
 */
 public static boolean isDesktopSupported(){
 Toolkit defaultToolkit = Toolkit.getDefaultToolkit();
 if (defaultToolkit instanceof SunToolkit) {
 return ((SunToolkit)defaultToolkit).isDesktopSupported();
 }
 return false;
 }

 /**
 * Tests whether an action is supported on the current platform.
 *
 * <p>Even when the platform supports an action, a file or URI may
 * not have a registered application for the action. For example,
 * most of the platforms support the {@link Desktop.Action#OPEN}
 * action. But for a specific file, there may not be an
 * application registered to open it. In this case, {@link
 * #isSupported} may return {@code true}, but the corresponding
 * action method will throw an {@link IOException}.
 *
 * @param action the specified {@link Action}
 * @return <code>true</code> if the specified action is supported on
 * the current platform; <code>false</code> otherwise
 * @see Desktop.Action
 */
 public boolean isSupported(Action action) {
 return peer.isSupported(action);
 }

 /**
 * Checks if the file is a valid file and readable.
 *
 * @throws SecurityException If a security manager exists and its
 * {@link SecurityManager#checkRead(java.lang.String)} method
 * denies read access to the file
 * @throws NullPointerException if file is null
 * @throws IllegalArgumentException if file doesn't exist
 */
 private static void checkFileValidation(File file) {
 if (!file.exists()) {
 throw new IllegalArgumentException("The file: "
 + file.getPath() + " doesn't exist.");
 }
 }

 /**
 * Checks if the action type is supported.
 *
 * @param actionType the action type in question
 * @throws UnsupportedOperationException if the specified action type is not
 * supported on the current platform
 */
 private void checkActionSupport(Action actionType){
 if (!isSupported(actionType)) {
 throw new UnsupportedOperationException("The " + actionType.name()
 + " action is not supported on the current platform!");
 }
 }


 /**
 * Calls to the security manager's <code>checkPermission</code> method with
 * an <code>AWTPermission("showWindowWithoutWarningBanner")</code>
 * permission.
 */
 private void checkAWTPermission(){
 SecurityManager sm = System.getSecurityManager();
 if (sm != null) {
 sm.checkPermission(new AWTPermission(
 "showWindowWithoutWarningBanner"));
 }
 }

 /**
 * Launches the associated application to open the file.
 *
 * <p> If the specified file is a directory, the file manager of
 * the current platform is launched to open it.
 *
 * @param file the file to be opened with the associated application
 * @throws NullPointerException if {@code file} is {@code null}
 * @throws IllegalArgumentException if the specified file doesn't
 * exist
 * @throws UnsupportedOperationException if the current platform
 * does not support the {@link Desktop.Action#OPEN} action
 * @throws IOException if the specified file has no associated
 * application or the associated application fails to be launched
 * @throws SecurityException if a security manager exists and its
 * {@link java.lang.SecurityManager#checkRead(java.lang.String)}
 * method denies read access to the file, or it denies the
 * <code>AWTPermission("showWindowWithoutWarningBanner")</code>
 * permission, or the calling thread is not allowed to create a
 * subprocess
 * @see java.awt.AWTPermission
 */
 public void open(File file) throws IOException {
 file = new File(file.getPath());
 checkAWTPermission();
 checkExec();
 checkActionSupport(Action.OPEN);
 checkFileValidation(file);

 peer.open(file);
 }

 /**
 * Launches the associated editor application and opens a file for
 * editing.
 *
 * @param file the file to be opened for editing
 * @throws NullPointerException if the specified file is {@code null}
 * @throws IllegalArgumentException if the specified file doesn't
 * exist
 * @throws UnsupportedOperationException if the current platform
 * does not support the {@link Desktop.Action#EDIT} action
 * @throws IOException if the specified file has no associated
 * editor, or the associated application fails to be launched
 * @throws SecurityException if a security manager exists and its
 * {@link java.lang.SecurityManager#checkRead(java.lang.String)}
 * method denies read access to the file, or {@link
 * java.lang.SecurityManager#checkWrite(java.lang.String)} method
 * denies write access to the file, or it denies the
 * <code>AWTPermission("showWindowWithoutWarningBanner")</code>
 * permission, or the calling thread is not allowed to create a
 * subprocess
 * @see java.awt.AWTPermission
 */
 public void edit(File file) throws IOException {
 file = new File(file.getPath());
 checkAWTPermission();
 checkExec();
 checkActionSupport(Action.EDIT);
 file.canWrite();
 checkFileValidation(file);

 peer.edit(file);
 }

 /**
 * Prints a file with the native desktop printing facility, using
 * the associated application's print command.
 *
 * @param file the file to be printed
 * @throws NullPointerException if the specified file is {@code
 * null}
 * @throws IllegalArgumentException if the specified file doesn't
 * exist
 * @throws UnsupportedOperationException if the current platform
 * does not support the {@link Desktop.Action#PRINT} action
 * @throws IOException if the specified file has no associated
 * application that can be used to print it
 * @throws SecurityException if a security manager exists and its
 * {@link java.lang.SecurityManager#checkRead(java.lang.String)}
 * method denies read access to the file, or its {@link
 * java.lang.SecurityManager#checkPrintJobAccess()} method denies
 * the permission to print the file, or the calling thread is not
 * allowed to create a subprocess
 */
 public void print(File file) throws IOException {
 file = new File(file.getPath());
 checkExec();
 SecurityManager sm = System.getSecurityManager();
 if (sm != null) {
 sm.checkPrintJobAccess();
 }
 checkActionSupport(Action.PRINT);
 checkFileValidation(file);

 peer.print(file);
 }

 /**
 * Launches the default browser to display a {@code URI}.
 * If the default browser is not able to handle the specified
 * {@code URI}, the application registered for handling
 * {@code URIs} of the specified type is invoked. The application
 * is determined from the protocol and path of the {@code URI}, as
 * defined by the {@code URI} class.
 * <p>
 * If the calling thread does not have the necessary permissions,
 * and this is invoked from within an applet,
 * {@code AppletContext.showDocument()} is used. Similarly, if the calling
 * does not have the necessary permissions, and this is invoked from within
 * a Java Web Started application, {@code BasicService.showDocument()}
 * is used.
 *
 * @param uri the URI to be displayed in the user default browser
 * @throws NullPointerException if {@code uri} is {@code null}
 * @throws UnsupportedOperationException if the current platform
 * does not support the {@link Desktop.Action#BROWSE} action
 * @throws IOException if the user default browser is not found,
 * or it fails to be launched, or the default handler application
 * failed to be launched
 * @throws SecurityException if a security manager exists and it
 * denies the
 * <code>AWTPermission("showWindowWithoutWarningBanner")</code>
 * permission, or the calling thread is not allowed to create a
 * subprocess; and not invoked from within an applet or Java Web Started
 * application
 * @throws IllegalArgumentException if the necessary permissions
 * are not available and the URI can not be converted to a {@code URL}
 * @see java.net.URI
 * @see java.awt.AWTPermission
 * @see java.applet.AppletContext
 */
 public void browse(URI uri) throws IOException {
 SecurityException securityException = null;
 try {
 checkAWTPermission();
 checkExec();
 } catch (SecurityException e) {
 securityException = e;
 }
 checkActionSupport(Action.BROWSE);
 if (uri == null) {
 throw new NullPointerException();
 }
 if (securityException == null) {
 peer.browse(uri);
 return;
 }

 // Calling thread doesn't have necessary priviledges.
 // Delegate to DesktopBrowse so that it can work in
 // applet/webstart.
 URL url = null;
 try {
 url = uri.toURL();
 } catch (MalformedURLException e) {
 throw new IllegalArgumentException("Unable to convert URI to URL", e);
 }
 sun.awt.DesktopBrowse db = sun.awt.DesktopBrowse.getInstance();
 if (db == null) {
 // Not in webstart/applet, throw the exception.
 throw securityException;
 }
 db.browse(url);
 }

 /**
 * Launches the mail composing window of the user default mail
 * client.
 *
 * @throws UnsupportedOperationException if the current platform
 * does not support the {@link Desktop.Action#MAIL} action
 * @throws IOException if the user default mail client is not
 * found, or it fails to be launched
 * @throws SecurityException if a security manager exists and it
 * denies the
 * <code>AWTPermission("showWindowWithoutWarningBanner")</code>
 * permission, or the calling thread is not allowed to create a
 * subprocess
 * @see java.awt.AWTPermission
 */
 public void mail() throws IOException {
 checkAWTPermission();
 checkExec();
 checkActionSupport(Action.MAIL);
 URI mailtoURI = null;
 try{
 mailtoURI = new URI("mailto:?");
 peer.mail(mailtoURI);
 } catch (URISyntaxException e){
 // won't reach here.
 }
 }

 /**
 * Launches the mail composing window of the user default mail
 * client, filling the message fields specified by a {@code
 * mailto:} URI.
 *
 * <p> A <code>mailto:</code> URI can specify message fields
 * including <i>"to"</i>, <i>"cc"</i>, <i>"subject"</i>,
 * <i>"body"</i>, etc. See <a
 * href="http://www.ietf.org/rfc/rfc2368.txt">The mailto URL
 * scheme (RFC 2368)</a> for the {@code mailto:} URI specification
 * details.
 *
 * @param mailtoURI the specified {@code mailto:} URI
 * @throws NullPointerException if the specified URI is {@code
 * null}
 * @throws IllegalArgumentException if the URI scheme is not
 * <code>"mailto"</code>
 * @throws UnsupportedOperationException if the current platform
 * does not support the {@link Desktop.Action#MAIL} action
 * @throws IOException if the user default mail client is not
 * found or fails to be launched
 * @throws SecurityException if a security manager exists and it
 * denies the
 * <code>AWTPermission("showWindowWithoutWarningBanner")</code>
 * permission, or the calling thread is not allowed to create a
 * subprocess
 * @see java.net.URI
 * @see java.awt.AWTPermission
 */
 public void mail(URI mailtoURI) throws IOException {
 checkAWTPermission();
 checkExec();
 checkActionSupport(Action.MAIL);
 if (mailtoURI == null) throw new NullPointerException();

 if (!"mailto".equalsIgnoreCase(mailtoURI.getScheme())) {
 throw new IllegalArgumentException("URI scheme is not \"mailto\"");
 }

 peer.mail(mailtoURI);
 }

 private void checkExec() throws SecurityException {
 SecurityManager sm = System.getSecurityManager();
 if (sm != null) {
 sm.checkPermission(new FilePermission("<<ALL FILES>>",
 SecurityConstants.FILE_EXECUTE_ACTION));
 }
 }
}