From f911ba985aa7fe0096c386c5be385ac5825ea527 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Sat, 16 Jul 2005 00:30:23 +0000 Subject: Initial revision From-SVN: r102074 --- libjava/classpath/java/beans/Introspector.java | 608 +++++++++++++++++++++++++ 1 file changed, 608 insertions(+) create mode 100644 libjava/classpath/java/beans/Introspector.java (limited to 'libjava/classpath/java/beans/Introspector.java') diff --git a/libjava/classpath/java/beans/Introspector.java b/libjava/classpath/java/beans/Introspector.java new file mode 100644 index 00000000000..02781b46e0d --- /dev/null +++ b/libjava/classpath/java/beans/Introspector.java @@ -0,0 +1,608 @@ +/* java.beans.Introspector + Copyright (C) 1998, 2002, 2003 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.beans; + +import gnu.java.beans.BeanInfoEmbryo; +import gnu.java.beans.ExplicitBeanInfo; +import gnu.java.beans.IntrospectionIncubator; +import gnu.java.lang.ClassHelper; + +import java.util.Hashtable; +import java.util.Vector; + +/** + * Introspector is the class that does the bulk of the + * design-time work in Java Beans. Every class must have + * a BeanInfo in order for an RAD tool to use it; but, as + * promised, you don't have to write the BeanInfo class + * yourself if you don't want to. All you have to do is + * call getBeanInfo() in the Introspector and it will use + * standard JavaBeans-defined method signatures to + * determine the information about your class.

+ * + * Don't worry about it too much, though: you can provide + * JavaBeans with as much customized information as you + * want, or as little as you want, using the BeanInfo + * interface (see BeanInfo for details).

+ * + * Order of Operations

+ * + * When you call getBeanInfo(class c), the Introspector + * first searches for BeanInfo class to see if you + * provided any explicit information. It searches for a + * class named <bean class name>BeanInfo in different + * packages, first searching the bean class's package + * and then moving on to search the beanInfoSearchPath.

+ * + * If it does not find a BeanInfo class, it acts as though + * it had found a BeanInfo class returning null from all + * methods (meaning it should discover everything through + * Introspection). If it does, then it takes the + * information it finds in the BeanInfo class to be + * canonical (that is, the information speaks for its + * class as well as all superclasses).

+ * + * When it has introspected the class, calls + * getBeanInfo(c.getSuperclass) and adds that information + * to the information it has, not adding to any information + * it already has that is canonical.

+ * + * Introspection Design Patterns

+ * + * When the Introspector goes in to read the class, it + * follows a well-defined order in order to not leave any + * methods unaccounted for. Its job is to step over all + * of the public methods in a class and determine whether + * they are part of a property, an event, or a method (in + * that order). + * + * + * Properties:

+ * + *

    + *
  1. If there is a public boolean isXXX() + * method, then XXX is a read-only boolean property. + * boolean getXXX() may be supplied in + * addition to this method, although isXXX() is the + * one that will be used in this case and getXXX() + * will be ignored. If there is a + * public void setXXX(boolean) method, + * it is part of this group and makes it a read-write + * property.
    2. + *
  2. If there is a + * public <type> getXXX(int) + * method, then XXX is a read-only indexed property of + * type <type>. If there is a + * public void setXXX(int,<type>) + * method, then it is a read-write indexed property of + * type <type>. There may also be a + * public <type>[] getXXX() and a + * public void setXXX(<type>) + * method as well.
    3. + *
  3. If there is a + * public void setXXX(int,<type>) + * method, then it is a write-only indexed property of + * type <type>. There may also be a + * public <type>[] getXXX() and a + * public void setXXX(<type>) + * method as well.
    4. + *
  4. If there is a + * public <type> getXXX() method, + * then XXX is a read-only property of type + * <type>. If there is a + * public void setXXX(<type>) + * method, then it will be used for the property and + * the property will be considered read-write.
    5. + *
  5. If there is a + * public void setXXX(<type>) + * method, then as long as XXX is not already used as + * the name of a property, XXX is assumed to be a + * write-only property of type <type>.
    6. + *
  6. In all of the above cases, if the setXXX() method + * throws PropertyVetoException, then the + * property in question is assumed to be constrained. + * No properties are ever assumed to be bound + * (Spec Note: this is not in the + * spec, it just makes sense). See PropertyDescriptor + * for a description of bound and constrained + * properties.
    7. + *
+ * + * Events:

+ * + * If there is a pair of methods, + * public void addXXX(<type>) and + * public void removeXXX(<type>), where + * <type> is a descendant of + * java.util.EventListener, then the pair of + * methods imply that this Bean will fire events to + * listeners of type <type>.

+ * + * If the addXXX() method throws + * java.util.TooManyListenersException, then + * the event set is assumed to be unicast. See + * EventSetDescriptor for a discussion of unicast event + * sets.

+ * + * Spec Note: the spec seems to say that + * the listener type's classname must be equal to the XXX + * part of addXXX() and removeXXX(), but that is not the + * case in Sun's implementation, so I am assuming it is + * not the case in general.

+ * + * Methods:

+ * + * Any public methods (including those which were used + * for Properties or Events) are used as Methods. + * + * @author John Keiser + * @since JDK1.1 + * @see java.beans.BeanInfo + */ +public class Introspector { + + public static final int USE_ALL_BEANINFO = 1; + public static final int IGNORE_IMMEDIATE_BEANINFO = 2; + public static final int IGNORE_ALL_BEANINFO = 3; + + static String[] beanInfoSearchPath = {"gnu.java.beans.info"}; + static Hashtable beanInfoCache = new Hashtable(); + + private Introspector() {} + + /** + * Get the BeanInfo for class beanClass, + * first by looking for explicit information, next by + * using standard design patterns to determine + * information about the class. + * + * @param beanClass the class to get BeanInfo about. + * @return the BeanInfo object representing the class. + */ + public static BeanInfo getBeanInfo(Class beanClass) + throws IntrospectionException + { + BeanInfo cachedInfo; + synchronized(beanClass) + { + cachedInfo = (BeanInfo)beanInfoCache.get(beanClass); + if(cachedInfo != null) + { + return cachedInfo; + } + cachedInfo = getBeanInfo(beanClass,null); + beanInfoCache.put(beanClass,cachedInfo); + return cachedInfo; + } + } + + /** + * Flush all of the Introspector's internal caches. + * + * @since 1.2 + */ + public static void flushCaches() + { + beanInfoCache.clear(); + + // Clears all the intermediate ExplicitInfo instances which + // have been created. + // This makes sure we have to retrieve stuff like BeanDescriptors + // again. (Remember that FeatureDescriptor can be modified by the user.) + ExplicitInfo.flushCaches(); + } + + /** + * Flush the Introspector's internal cached information for a given + * class. + * + * @param clz the class to be flushed. + * @throws NullPointerException if clz is null. + * @since 1.2 + */ + public static void flushFromCaches(Class clz) + { + synchronized (clz) + { + beanInfoCache.remove(clz); + } + } + + /** + * Get the BeanInfo for class beanClass, + * first by looking for explicit information, next by + * using standard design patterns to determine + * information about the class. It crawls up the + * inheritance tree until it hits topClass. + * + * @param beanClass the Bean class. + * @param stopClass the class to stop at. + * @return the BeanInfo object representing the class. + */ + public static BeanInfo getBeanInfo(Class beanClass, Class stopClass) + throws IntrospectionException + { + ExplicitInfo explicit = new ExplicitInfo(beanClass, stopClass); + + IntrospectionIncubator ii = new IntrospectionIncubator(); + ii.setPropertyStopClass(explicit.propertyStopClass); + ii.setEventStopClass(explicit.eventStopClass); + ii.setMethodStopClass(explicit.methodStopClass); + ii.addMethods(beanClass.getMethods()); + + BeanInfoEmbryo currentInfo = ii.getBeanInfoEmbryo(); + PropertyDescriptor[] p = explicit.explicitPropertyDescriptors; + if(p!=null) + { + for(int i=0;i