439 lines
15 KiB
Java
439 lines
15 KiB
Java
/* java.beans.Introspector
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Copyright (C) 1998 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 gnu.java.beans.*;
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import java.util.*;
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import java.lang.reflect.*;
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import gnu.java.lang.*;
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/**
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** Introspector is the class that does the bulk of the
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** design-time work in Java Beans. Every class must have
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** a BeanInfo in order for an RAD tool to use it; but, as
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** promised, you don't have to write the BeanInfo class
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** yourself if you don't want to. All you have to do is
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** call getBeanInfo() in the Introspector and it will use
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** standard JavaBeans-defined method signatures to
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** determine the information about your class.<P>
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**
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** Don't worry about it too much, though: you can provide
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** JavaBeans with as much customized information as you
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** want, or as little as you want, using the BeanInfo
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** interface (see BeanInfo for details).<P>
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**
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** <STRONG>Order of Operations</STRONG><P>
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**
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** When you call getBeanInfo(class c), the Introspector
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** first searches for BeanInfo class to see if you
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** provided any explicit information. It searches for a
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** class named <bean class name>BeanInfo in different
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** packages, first searching the bean class's package
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** and then moving on to search the beanInfoSearchPath.<P>
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**
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** If it does not find a BeanInfo class, it acts as though
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** it had found a BeanInfo class returning null from all
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** methods (meaning it should discover everything through
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** Introspection). If it does, then it takes the
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** information it finds in the BeanInfo class to be
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** canonical (that is, the information speaks for its
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** class as well as all superclasses).<P>
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**
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** When it has introspected the class, calls
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** getBeanInfo(c.getSuperclass) and adds that information
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** to the information it has, not adding to any information
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** it already has that is canonical.<P>
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**
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** <STRONG>Introspection Design Patterns</STRONG><P>
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**
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** When the Introspector goes in to read the class, it
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** follows a well-defined order in order to not leave any
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** methods unaccounted for. Its job is to step over all
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** of the public methods in a class and determine whether
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** they are part of a property, an event, or a method (in
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** that order).
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**
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**
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** <STRONG>Properties:</STRONG><P>
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**
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** <OL>
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** <LI>If there is a <CODE>public boolean isXXX()</CODE>
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** method, then XXX is a read-only boolean property.
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** <CODE>boolean getXXX()</CODE> may be supplied in
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** addition to this method, although isXXX() is the
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** one that will be used in this case and getXXX()
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** will be ignored. If there is a
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** <CODE>public void setXXX(boolean)</CODE> method,
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** it is part of this group and makes it a read-write
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** property.</LI>
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** <LI>If there is a
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** <CODE>public <type> getXXX(int)</CODE>
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** method, then XXX is a read-only indexed property of
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** type <type>. If there is a
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** <CODE>public void setXXX(int,<type>)</CODE>
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** method, then it is a read-write indexed property of
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** type <type>. There may also be a
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** <CODE>public <type>[] getXXX()</CODE> and a
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** <CODE>public void setXXX(<type>)</CODE>
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** method as well.</CODE></LI>
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** <LI>If there is a
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** <CODE>public void setXXX(int,<type>)</CODE>
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** method, then it is a write-only indexed property of
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** type <type>. There may also be a
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** <CODE>public <type>[] getXXX()</CODE> and a
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** <CODE>public void setXXX(<type>)</CODE>
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** method as well.</CODE></LI>
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** <LI>If there is a
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** <CODE>public <type> getXXX()</CODE> method,
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** then XXX is a read-only property of type
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** <type>. If there is a
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** <CODE>public void setXXX(<type>)</CODE>
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** method, then it will be used for the property and
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** the property will be considered read-write.</LI>
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** <LI>If there is a
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** <CODE>public void setXXX(<type>)</CODE>
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** method, then as long as XXX is not already used as
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** the name of a property, XXX is assumed to be a
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** write-only property of type <type>.</LI>
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** <LI>In all of the above cases, if the setXXX() method
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** throws <CODE>PropertyVetoException</CODE>, then the
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** property in question is assumed to be constrained.
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** No properties are ever assumed to be bound
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** (<STRONG>Spec Note:</STRONG> this is not in the
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** spec, it just makes sense). See PropertyDescriptor
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** for a description of bound and constrained
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** properties.</LI>
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** </OL>
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**
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** <STRONG>Events:</STRONG><P>
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**
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** If there is a pair of methods,
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** <CODE>public void addXXX(<type>)</CODE> and
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** <CODE>public void removeXXX(<type>)</CODE>, where
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** <type> is a descendant of
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** <CODE>java.util.EventListener</CODE>, then the pair of
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** methods imply that this Bean will fire events to
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** listeners of type <type>.<P>
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**
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** If the addXXX() method throws
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** <CODE>java.util.TooManyListenersException</CODE>, then
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** the event set is assumed to be <EM>unicast</EM>. See
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** EventSetDescriptor for a discussion of unicast event
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** sets.<P>
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**
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** <STRONG>Spec Note:</STRONG> the spec seems to say that
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** the listener type's classname must be equal to the XXX
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** part of addXXX() and removeXXX(), but that is not the
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** case in Sun's implementation, so I am assuming it is
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** not the case in general.<P>
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**
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** <STRONG>Methods:</STRONG><P>
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**
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** Any public methods (including those which were used
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** for Properties or Events) are used as Methods.
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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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** @see java.beans.BeanInfo
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**/
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public class Introspector {
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static String[] beanInfoSearchPath = {"gnu.java.beans.info", "sun.beans.infos"};
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static Hashtable beanInfoCache = new Hashtable();
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private Introspector() {}
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/** Get the BeanInfo for class <CODE>beanClass</CODE>,
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** first by looking for explicit information, next by
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** using standard design patterns to determine
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** information about the class.
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** @param beanClass the class to get BeanInfo about.
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** @return the BeanInfo object representing the class.
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**/
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public static BeanInfo getBeanInfo(Class beanClass) throws IntrospectionException {
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BeanInfo cachedInfo;
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synchronized(beanClass) {
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cachedInfo = (BeanInfo)beanInfoCache.get(beanClass);
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if(cachedInfo != null) {
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return cachedInfo;
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}
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cachedInfo = getBeanInfo(beanClass,null);
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beanInfoCache.put(beanClass,cachedInfo);
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return cachedInfo;
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}
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}
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/** Get the BeanInfo for class <CODE>beanClass</CODE>,
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** first by looking for explicit information, next by
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** using standard design patterns to determine
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** information about the class. It crawls up the
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** inheritance tree until it hits <CODE>topClass</CODE>.
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** @param beanClass the Bean class.
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** @param stopClass the class to stop at.
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** @return the BeanInfo object representing the class.
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**/
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public static BeanInfo getBeanInfo(Class beanClass, Class stopClass) throws IntrospectionException {
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ExplicitInfo explicit = new ExplicitInfo(beanClass,stopClass);
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IntrospectionIncubator ii = new IntrospectionIncubator();
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ii.setPropertyStopClass(explicit.propertyStopClass);
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ii.setEventStopClass(explicit.eventStopClass);
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ii.setMethodStopClass(explicit.methodStopClass);
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ii.addMethods(beanClass.getMethods());
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BeanInfoEmbryo currentInfo = ii.getBeanInfoEmbryo();
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PropertyDescriptor[] p = explicit.explicitPropertyDescriptors;
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if(p!=null) {
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for(int i=0;i<p.length;i++) {
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if(!currentInfo.hasProperty(p[i])) {
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currentInfo.addProperty(p[i]);
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}
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}
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if(explicit.defaultProperty != -1) {
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currentInfo.setDefaultPropertyName(p[explicit.defaultProperty].getName());
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}
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}
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EventSetDescriptor[] e = explicit.explicitEventSetDescriptors;
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if(e!=null) {
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for(int i=0;i<e.length;i++) {
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if(!currentInfo.hasEvent(e[i])) {
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currentInfo.addEvent(e[i]);
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}
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}
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if(explicit.defaultEvent != -1) {
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currentInfo.setDefaultEventName(e[explicit.defaultEvent].getName());
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}
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}
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MethodDescriptor[] m = explicit.explicitMethodDescriptors;
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if(m!=null) {
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for(int i=0;i<m.length;i++) {
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if(!currentInfo.hasMethod(m[i])) {
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currentInfo.addMethod(m[i]);
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}
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}
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}
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if(explicit.explicitBeanDescriptor != null) {
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currentInfo.setBeanDescriptor(new BeanDescriptor(beanClass,explicit.explicitBeanDescriptor.getCustomizerClass()));
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} else {
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currentInfo.setBeanDescriptor(new BeanDescriptor(beanClass,null));
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}
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currentInfo.setAdditionalBeanInfo(explicit.explicitBeanInfo);
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currentInfo.setIcons(explicit.im);
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return currentInfo.getBeanInfo();
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}
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/** Get the search path for BeanInfo classes.
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** @return the BeanInfo search path.
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**/
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public static String[] getBeanInfoSearchPath() {
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return beanInfoSearchPath;
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}
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/** Set the search path for BeanInfo classes.
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** @param beanInfoSearchPath the new BeanInfo search
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** path.
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**/
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public static void setBeanInfoSearchPath(String[] beanInfoSearchPath) {
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Introspector.beanInfoSearchPath = beanInfoSearchPath;
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}
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/** A helper method to convert a name to standard Java
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** naming conventions: anything with two capitals as the
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** first two letters remains the same, otherwise the
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** first letter is decapitalized. URL = URL, I = i,
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** MyMethod = myMethod.
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** @param name the name to decapitalize.
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** @return the decapitalized name.
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**/
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public static String decapitalize(String name) {
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try {
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if(!Character.isUpperCase(name.charAt(0))) {
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return name;
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} else {
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try {
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if(Character.isUpperCase(name.charAt(1))) {
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return name;
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} else {
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char[] c = name.toCharArray();
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c[0] = Character.toLowerCase(c[0]);
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return new String(c);
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}
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} catch(StringIndexOutOfBoundsException E) {
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char[] c = new char[1];
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c[0] = Character.toLowerCase(name.charAt(0));
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return new String(c);
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}
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}
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} catch(StringIndexOutOfBoundsException E) {
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return name;
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} catch(NullPointerException E) {
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return null;
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}
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}
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static BeanInfo copyBeanInfo(BeanInfo b) {
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java.awt.Image[] icons = new java.awt.Image[4];
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for(int i=1;i<=4;i++) {
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icons[i-1] = b.getIcon(i);
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}
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return new ExplicitBeanInfo(b.getBeanDescriptor(),b.getAdditionalBeanInfo(),
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b.getPropertyDescriptors(),b.getDefaultPropertyIndex(),
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b.getEventSetDescriptors(),b.getDefaultEventIndex(),
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b.getMethodDescriptors(),icons);
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}
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}
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class ExplicitInfo {
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BeanDescriptor explicitBeanDescriptor;
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BeanInfo[] explicitBeanInfo;
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PropertyDescriptor[] explicitPropertyDescriptors;
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EventSetDescriptor[] explicitEventSetDescriptors;
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MethodDescriptor[] explicitMethodDescriptors;
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int defaultProperty;
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int defaultEvent;
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java.awt.Image[] im = new java.awt.Image[4];
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Class propertyStopClass;
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Class eventStopClass;
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Class methodStopClass;
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ExplicitInfo(Class beanClass, Class stopClass) {
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while(beanClass != null && !beanClass.equals(stopClass)) {
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BeanInfo explicit = findExplicitBeanInfo(beanClass);
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if(explicit != null) {
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if(explicitBeanDescriptor == null) {
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explicitBeanDescriptor = explicit.getBeanDescriptor();
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}
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if(explicitBeanInfo == null) {
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explicitBeanInfo = explicit.getAdditionalBeanInfo();
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}
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if(explicitPropertyDescriptors == null) {
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if(explicit.getPropertyDescriptors() != null) {
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explicitPropertyDescriptors = explicit.getPropertyDescriptors();
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defaultProperty = explicit.getDefaultPropertyIndex();
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propertyStopClass = beanClass;
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}
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}
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if(explicitEventSetDescriptors == null) {
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if(explicit.getEventSetDescriptors() != null) {
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explicitEventSetDescriptors = explicit.getEventSetDescriptors();
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defaultEvent = explicit.getDefaultEventIndex();
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eventStopClass = beanClass;
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}
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}
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if(explicitMethodDescriptors == null) {
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if(explicit.getMethodDescriptors() != null) {
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explicitMethodDescriptors = explicit.getMethodDescriptors();
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methodStopClass = beanClass;
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}
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}
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if(im[0] == null
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&& im[1] == null
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&& im[2] == null
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&& im[3] == null) {
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im[0] = explicit.getIcon(0);
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im[1] = explicit.getIcon(1);
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im[2] = explicit.getIcon(2);
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im[3] = explicit.getIcon(3);
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}
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}
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beanClass = beanClass.getSuperclass();
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}
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if(propertyStopClass == null) {
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propertyStopClass = stopClass;
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}
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if(eventStopClass == null) {
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eventStopClass = stopClass;
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}
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if(methodStopClass == null) {
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methodStopClass = stopClass;
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}
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}
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static Hashtable explicitBeanInfos = new Hashtable();
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static Vector emptyBeanInfos = new Vector();
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static BeanInfo findExplicitBeanInfo(Class beanClass) {
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BeanInfo retval = (BeanInfo)explicitBeanInfos.get(beanClass);
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if(retval != null) {
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return retval;
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} else if(emptyBeanInfos.indexOf(beanClass) != -1) {
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return null;
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} else {
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retval = reallyFindExplicitBeanInfo(beanClass);
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if(retval != null) {
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explicitBeanInfos.put(beanClass,retval);
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} else {
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emptyBeanInfos.addElement(beanClass);
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}
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return retval;
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}
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}
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static BeanInfo reallyFindExplicitBeanInfo(Class beanClass) {
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try {
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try {
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return (BeanInfo)Class.forName(beanClass.getName()+"BeanInfo").newInstance();
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} catch(ClassNotFoundException E) {
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}
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String newName = ClassHelper.getTruncatedClassName(beanClass) + "BeanInfo";
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for(int i=0;i<Introspector.beanInfoSearchPath.length;i++) {
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try {
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if(Introspector.beanInfoSearchPath[i].equals("")) {
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return (BeanInfo)Class.forName(newName).newInstance();
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} else {
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return (BeanInfo)Class.forName(Introspector.beanInfoSearchPath[i] + "." + newName).newInstance();
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}
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} catch(ClassNotFoundException E) {
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}
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}
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} catch(IllegalAccessException E) {
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} catch(InstantiationException E) {
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}
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return null;
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}
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}
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