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The Desktop.java Java example source code
/*
* Copyright (c) 2005, 2006, 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.
*/
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 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 if this class is supported on the
* current platform; <code>false 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 if the specified action is supported on
* the current platform; <code>false 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 == null) throw new NullPointerException("File must not be null");
if (!file.exists()) {
throw new IllegalArgumentException("The file: "
+ file.getPath() + " doesn't exist.");
}
file.canRead();
}
/**
* 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 method with
* an <code>AWTPermission("showWindowWithoutWarningBanner")
* 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")
* permission, or the calling thread is not allowed to create a
* subprocess
* @see java.awt.AWTPermission
*/
public void open(File file) throws IOException {
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")
* permission, or the calling thread is not allowed to create a
* subprocess
* @see java.awt.AWTPermission
*/
public void edit(File file) throws IOException {
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 {
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")
* 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")
* 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 mailto: URI can specify message fields
* including <i>"to", "cc", "subject",
* <i>"body", etc. See
* @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")
* 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("<",
SecurityConstants.FILE_EXECUTE_ACTION));
}
}
}
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