Starting to reorganize serializer a bit to later add

some features that will make it slightly less fragile.
The code that registers a serializer for an ID has
been centralized.
A method was added to hand out new IDs and it now
skips IDs that are already in use.  This will allow
certain serializers to be fixed against specific IDs
to maintain backwards and forwards compatability even
as the automatically registered list of serializers
changes.


git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@9455 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/networking/com/jme3/network/serializing/Serializer.java

@@ -69,7 +69,7 @@ public abstract class Serializer {
     private static final Serializer                         serializableSerializer  = new SerializableSerializer();
     private static final Serializer                         arraySerializer         = new ArraySerializer();
 
-    private static short                                    nextId                  = -1;
+    private static short nextAvailableId = -2; // historically the first ID was always -2
 
     private static boolean strictRegistration = true;
 
@@ -139,6 +139,7 @@ public abstract class Serializer {
         registerClass(HashMap.class,                    new MapSerializer());
         registerClass(Hashtable.class,                  new MapSerializer());
         registerClass(IdentityHashMap.class,            new MapSerializer());
+        //registerClass(java.awt.RenderingHints.class,    new MapSerializer());
         registerClass(TreeMap.class,                    new MapSerializer());
         registerClass(WeakHashMap.class,                new MapSerializer());
         
@@ -171,6 +172,33 @@ public abstract class Serializer {
         }
     }
     
+    private static short nextId() {
+    
+        // If the ID we are about to return is already in use
+        // then skip it.
+        while (idRegistrations.containsKey(nextAvailableId) ) {
+            nextAvailableId--;   
+        }
+        
+        // Return the available ID and post-decrement to get
+        // ready for next time.    
+        return nextAvailableId--;
+    }
+ 
+    protected static SerializerRegistration registerClassForId( short id, Class cls, Serializer serializer ) {
+    
+        SerializerRegistration reg = new SerializerRegistration(serializer, cls, id);
+
+        idRegistrations.put(id, reg);
+        classRegistrations.put(cls, reg);
+        
+        log.log( Level.INFO, "Registered class[" + id + "]:{0} to:" + serializer, cls );
+
+        serializer.initialize(cls);
+
+        return reg;    
+    }
+    
     /**
      *  Registers the specified class. The failOnMiss flag controls whether or
      *  not this method returns null for failed registration or throws an exception.
@@ -182,7 +210,7 @@ public abstract class Serializer {
 
             Class serializerClass = serializable.serializer();
             short classId = serializable.id();
-            if (classId == 0) classId = --nextId;
+            if (classId == 0) classId = nextId();
 
             Serializer serializer = getSerializer(serializerClass, false);
 
@@ -191,15 +219,10 @@ public abstract class Serializer {
             SerializerRegistration existingReg = getExactSerializerRegistration(cls);
 
             if (existingReg != null) classId = existingReg.getId();
+            
             SerializerRegistration reg = new SerializerRegistration(serializer, cls, classId);
 
-            idRegistrations.put(classId, reg);
-            classRegistrations.put(cls, reg);
-
-            serializer.initialize(cls);
-
-            log.log( Level.INFO, "Registered class[" + classId + "]:{0}.", cls );
-            return reg;
+            return registerClassForId( classId, cls, serializer );
         }
         if (failOnMiss) {
             throw new IllegalArgumentException( "Class is not marked @Serializable:" + cls );            
@@ -263,18 +286,9 @@ public abstract class Serializer {
         if (existingReg != null) { 
             id = existingReg.getId();
         } else {
-            id = --nextId;
+            id = nextId();
         }            
-        SerializerRegistration reg = new SerializerRegistration(serializer, cls, id);
-
-        idRegistrations.put(id, reg);
-        classRegistrations.put(cls, reg);
-        
-        log.log( Level.INFO, "Registered class[" + id + "]:{0} to:" + serializer, cls );
-
-        serializer.initialize(cls);
-
-        return reg;
+        return registerClassForId( id, cls, serializer );
     }
 
     public static Serializer getExactSerializer(Class cls) {