Re: [cp-patches] FYI: XMLEncoder - less dependencies & bugfix

[Robert Schuster]

Hi,
the changelog was missing the info about the changes in 
DefaultPersistenceDelegate.

Fixed that.

2006-01-24  Robert Schuster  <address@hidden>

        * java/beans/XMLEncoder.java:
        (writeExpression): Added early return (fixes PR #25941).
        * java/beans/Encoder: Removed unused imports.
        (setupDefaultPersistenceDelegates): Removed unneccessary
        PersistenceDelegates for subclasses.
        * java/beans/PersistenceDelegate:
        (initialize): Use local variable as first argument as it was
        intended once.
        * java/beans/DefaultPersistenceDelegate:
        (initialize): Added call to superclass' implementation, added
        early return.


Robert Schuster wrote:
> Hi,
> I spend some time finding out how the JDK makes it possible that a
> PersistenceDelegate registered for AbstractMap is used for all its subclasses.
> 
> The funny thing is that the whole behavior depends on three places. Two of 
> them
> were implemented already because they are part of the spec. The final 
> component
> consists only of one line (calling super.inititialize() in
> DefaultPersistenceDelegate.initialize()).
> 
> Along the lines I found out that the XMLEncoder gets into an endless recursion
> when it serializes a class which is not public. The problem is not specific to
> this case the recursion would happen in any when an exception occurs during 
> the
> Expression.getValue() call. A simple early "return" fixes that. I have to 
> admit
> that the wrong behavior slipped in when I copied most of
> Encoder.writeExpression's code into XMLEncoder.writeExpression. Anyway this
> fixes PR #25941 .
> 
> The ChangeLog entry:
> 
> 2006-01-24  Robert Schuster  <address@hidden>
> 
>         * java/beans/XMLEncoder.java:
>         (writeExpression): Added early return (fixes PR #25941).
>         * java/beans/Encoder: Removed unused imports.
>         (setupDefaultPersistenceDelegates): Removed unneccessary
>         PersistenceDelegates for subclasses.
>         * java/beans/PersistenceDelegate:
>         (initialize): Use local variable as first argument as it was
>         intended once.
> 
> 
> 
> ------------------------------------------------------------------------
> 
> Index: java/beans/DefaultPersistenceDelegate.java
> ===================================================================
> RCS file: 
> /cvsroot/classpath/classpath/java/beans/DefaultPersistenceDelegate.java,v
> retrieving revision 1.1
> diff -u -r1.1 DefaultPersistenceDelegate.java
> --- java/beans/DefaultPersistenceDelegate.java        8 Jan 2006 19:31:38 
> -0000       1.1
> +++ java/beans/DefaultPersistenceDelegate.java        24 Jan 2006 16:42:17 
> -0000
> @@ -157,6 +157,23 @@
>    protected void initialize(Class type, Object oldInstance, Object 
> newInstance,
>                              Encoder out)
>    {
> +    // Calling the supertype's implementation of initialize makes it
> +    // possible that descendants of classes like AbstractHashMap
> +    // or Hashtable are serialized correctly. This mechanism grounds on
> +    // two other facts:
> +    // * Each class which has not registered a special purpose
> +    //   PersistenceDelegate is handled by a DefaultPersistenceDelegate
> +    //   instance.
> +    // * PersistenceDelegate.initialize() is implemented in a way that it
> +    //   calls the initialize method of the superclass' persistence delegate.
> +    super.initialize(type, oldInstance, newInstance, out);
> +    
> +    // Suppresses the writing of property setting statements when this 
> delegate
> +    // is not used for the exact instance type. By doing so the following 
> code
> +    // is called only once per object.
> +    if (type != oldInstance.getClass())
> +      return;
> +    
>      try
>        {
>          PropertyDescriptor[] propertyDescs = Introspector.getBeanInfo(
> Index: java/beans/Encoder.java
> ===================================================================
> RCS file: /cvsroot/classpath/classpath/java/beans/Encoder.java,v
> retrieving revision 1.1
> diff -u -r1.1 Encoder.java
> --- java/beans/Encoder.java   8 Jan 2006 19:31:38 -0000       1.1
> +++ java/beans/Encoder.java   24 Jan 2006 16:42:17 -0000
> @@ -44,15 +44,9 @@
>  import gnu.java.beans.encoder.MapPersistenceDelegate;
>  import gnu.java.beans.encoder.PrimitivePersistenceDelegate;
>  
> -import java.util.ArrayList;
> +import java.util.AbstractCollection;
>  import java.util.HashMap;
> -import java.util.HashSet;
>  import java.util.IdentityHashMap;
> -import java.util.LinkedHashSet;
> -import java.util.LinkedList;
> -import java.util.TreeMap;
> -import java.util.TreeSet;
> -import java.util.Vector;
>  
>  /**
>   * @author Robert Schuster (address@hidden)
> @@ -123,31 +117,11 @@
>          delegates.put(Object[].class, new ArrayPersistenceDelegate());
>  
>          pd = new CollectionPersistenceDelegate();
> -        delegates.put(ArrayList.class, pd);
> -        delegates.put(LinkedList.class, pd);
> -        delegates.put(Vector.class, pd);
> -        delegates.put(HashSet.class, pd);
> -        delegates.put(LinkedHashSet.class, pd);
> -        delegates.put(TreeSet.class, pd);
> +        delegates.put(AbstractCollection.class, pd);
>          
>          pd = new MapPersistenceDelegate();
> -        delegates.put(HashMap.class, pd);
> -        delegates.put(TreeMap.class, pd);
> +        delegates.put(java.util.AbstractMap.class, pd);
>          delegates.put(java.util.Hashtable.class, pd);
> -        delegates.put(java.util.IdentityHashMap.class, pd);
> -        
> -        delegates.put(java.util.LinkedHashMap.class, pd);
> -        delegates.put(java.util.Properties.class, pd);
> -
> -        delegates.put(java.awt.RenderingHints.class, pd);
> -        delegates.put(java.util.WeakHashMap.class, pd);
> -        delegates.put(javax.swing.UIDefaults.class, pd);
> -        
> -        // TODO: These classes need to be implemented first
> -        //delegates.put(java.security.AuthProvider.class, pd);
> -        //delegates.put(java.util.concurrent.ConcurrentHashMap.class, pd);
> -        //delegates.put(java.util.EnumMap.class, pd);
> -        //delegates.put(javax.management.openmbean.TabularDataSupport.class, 
> pd);
>          
>          defaultPersistenceDelegate = new DefaultPersistenceDelegate();
>          delegates.put(Object.class, defaultPersistenceDelegate);
> @@ -199,7 +173,6 @@
>        public void exceptionThrown(Exception e)
>        {
>          System.err.println("exception thrown: " + e);
> -        e.printStackTrace();
>        }
>      };
>    }
> Index: java/beans/PersistenceDelegate.java
> ===================================================================
> RCS file: /cvsroot/classpath/classpath/java/beans/PersistenceDelegate.java,v
> retrieving revision 1.1
> diff -u -r1.1 PersistenceDelegate.java
> --- java/beans/PersistenceDelegate.java       8 Jan 2006 19:31:38 -0000       
> 1.1
> +++ java/beans/PersistenceDelegate.java       24 Jan 2006 16:42:17 -0000
> @@ -59,9 +59,8 @@
>        {
>          type = type.getSuperclass();
>  
> -        PersistenceDelegate pd = out.getPersistenceDelegate(
> -          oldInstance.getClass().getSuperclass());
> -
> +        PersistenceDelegate pd = out.getPersistenceDelegate(type);
> +        
>          pd.initialize(type, oldInstance, newInstance, out);
>        }
>    }
> Index: java/beans/XMLEncoder.java
> ===================================================================
> RCS file: /cvsroot/classpath/classpath/java/beans/XMLEncoder.java,v
> retrieving revision 1.1
> diff -u -r1.1 XMLEncoder.java
> --- java/beans/XMLEncoder.java        8 Jan 2006 19:31:38 -0000       1.1
> +++ java/beans/XMLEncoder.java        24 Jan 2006 16:42:17 -0000
> @@ -168,6 +168,8 @@
>              // an erroneous state to the ScanEngine without behaving 
> different
>              // to the JDK.            
>              scanEngine.revoke();
> +            
> +            return;
>            }
>          
>          writeObject(value);
> 
> 
> ------------------------------------------------------------------------
> 
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> address@hidden
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