209 lines
6.4 KiB
Java
209 lines
6.4 KiB
Java
/* java.beans.Beans
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Copyright (C) 1998, 1999 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.beans;
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import java.io.*;
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import java.applet.*;
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import gnu.java.io.*;
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/**
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* <code>Beans</code> provides some helper methods that allow the basic operations of Bean-ness.
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*
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* @author John Keiser
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* @since JDK1.1
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* @version 1.1.0, 29 Jul 1998
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*
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*/
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public class Beans {
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static boolean designTime = false;
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static boolean guiAvailable = true;
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/**
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* Once again, we have a java.beans class with only
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* static methods that can be instantiated. When
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* will the madness end? :)
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*/
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public Beans() {
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}
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/**
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* Allows you to instantiate a Bean. This method takes
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* a ClassLoader from which to read the Bean and the
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* name of the Bean.<P>
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*
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* The Bean name should be a dotted name, like a class.
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* It can represent several things. Beans will search
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* for the Bean using the name like this:<P>
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* <OL>
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* <LI>Searches for a serialized instance of the Bean
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* using getResource(), mangling the Bean name by
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* replacing the dots with slashes and appending .ser
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* (for example, gnu.beans.BlahDeBlah would cause
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* Beans to search for gnu/beans/BlahDeBlah.ser using
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* getResource()).</LI>
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* <LI>Searches for the Bean class using the beanName,
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* and then instantiates it with the no-arg constructor.
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* At that point, if it is an Applet, it provides it
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* with AppletContext and AppletStub, and then calls
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* init().</LI>
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* </OL>
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* @param cl the ClassLoader to use, or <CODE>null</CODE>
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* to use the default ClassLoader.
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* @param beanName the name of the Bean.
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* @return the Bean.
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* @XXX
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*/
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public static Object instantiate(ClassLoader cl, String beanName) throws IOException, ClassNotFoundException {
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Object bean;
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InputStream serStream;
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if(cl == null) {
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serStream = ClassLoader.getSystemResourceAsStream(beanName.replace('.','/')+".ser");
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} else {
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serStream = cl.getResourceAsStream(beanName.replace('.','/')+".ser");
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}
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if(serStream != null) {
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if(cl == null) {
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ObjectInputStream ois = new ObjectInputStream(serStream);
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bean = ois.readObject();
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} else {
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ClassLoaderObjectInputStream ois = new ClassLoaderObjectInputStream(serStream, cl);
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bean = ois.readObject();
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}
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} else if(cl == null) {
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Class beanClass = Class.forName(beanName);
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try {
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bean = beanClass.newInstance();
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} catch(IllegalAccessException E) {
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bean = null;
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} catch(InstantiationException E) {
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bean = null;
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}
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} else {
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Class beanClass = cl.loadClass(beanName);
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try {
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bean = beanClass.newInstance();
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} catch(IllegalAccessException E) {
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bean = null;
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} catch(InstantiationException E) {
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bean = null;
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}
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}
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if(bean instanceof Applet) {
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Applet a = (Applet)bean;
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//a.setAppletContext(???);
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//a.setStub(???);
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if(serStream == null) {
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a.init();
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}
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}
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return bean;
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}
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/**
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* Get the Bean as a different class type.
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* This should be used instead of casting to get a new
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* type view of a Bean, because in the future there may
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* be new types of Bean, even Beans spanning multiple
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* Objects.
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* @param bean the Bean to cast.
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* @param newClass the Class to cast it to.
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* @return the Bean as a new view, or if the operation
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* could not be performed, the Bean itself.
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*/
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public static Object getInstanceOf(Object bean, Class newClass) {
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return bean;
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}
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/**
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* Determine whether the Bean can be cast to a different
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* class type.
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* This should be used instead of instanceof to determine
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* a Bean's castability, because in the future there may
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* be new types of Bean, even Beans spanning multiple
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* Objects.
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* @param bean the Bean to cast.
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* @param newClass the Class to cast it to.
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* @return whether the Bean can be cast to the class type
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* in question.
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*/
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public static boolean isInstanceOf(Object bean, Class newBeanClass) {
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return newBeanClass.isInstance(bean);
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}
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/**
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* Find out whether the GUI is available to use.
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* Defaults to true.
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* @return whether the GUI is available to use.
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*/
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public static boolean isGuiAvailable() {
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return guiAvailable;
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}
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/**
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* Find out whether it is design time. Design time means
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* we are in a RAD tool.
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* Defaults to false.
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* @return whether it is design time.
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*/
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public static boolean isDesignTime() {
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return designTime;
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}
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/**
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* Set whether the GUI is available to use.
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* @param guiAvailable whether the GUI is available to use.
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*/
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public static void setGuiAvailable(boolean guiAvailable) throws SecurityException {
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Beans.guiAvailable = guiAvailable;
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}
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/**
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* Set whether it is design time. Design time means we
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* are in a RAD tool.
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* @param designTime whether it is design time.
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*/
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public static void setDesignTime(boolean designTime) throws SecurityException {
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Beans.designTime = designTime;
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}
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}
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