Work on #2539 (for master first)

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/databind/deser/BasicDeserializerFactory.java

@@ -1568,7 +1568,7 @@ protected JsonDeserializer<?> findOptionalStdDeserializer(DeserializationContext
     {
         return OptionalHandlerFactory.instance.findDeserializer(ctxt.getConfig(), type);
     }
-    
+
     /*
     /**********************************************************************
     /* DeserializerFactory impl (partial): key deserializers
@@ -1728,7 +1728,7 @@ public JsonDeserializer<?> findDefaultDeserializer(DeserializationContext ctxt,
         String clsName = rawType.getName();
         if (rawType.isPrimitive() || clsName.startsWith("java.")) {
             // Primitives/wrappers, other Numbers:
-            JsonDeserializer<?> deser = NumberDeserializers.find(rawType, clsName);
+            JsonDeserializer<?> deser = NumberDeserializers.find(rawType);
             if (deser == null) {
                 deser = DateDeserializers.find(rawType, clsName);
             }
@@ -1747,6 +1747,45 @@ public JsonDeserializer<?> findDefaultDeserializer(DeserializationContext ctxt,
         return StdJdkDeserializers.find(rawType, clsName);
     }
 
+    /**
+     * Method that can be used to check if databind module has deserializer
+     * for given (likely JDK) type: explicit meaning that it is not automatically
+     * generated for POJO.
+     *<p>
+     * This matches {@link Deserializers#hasDeserializerFor(Class)} method.
+     *
+     * @since 3.0
+     */
+    protected boolean hasExplicitDeserializerFor(Class<?> valueType) {
+        // Yes, we handle all Enum types
+        if (Enum.class.isAssignableFrom(valueType)) {
+            return true;
+        }
+        // Numbers?
+        final String clsName = valueType.getName();
+        if (clsName.startsWith("java.")) {
+            if (Number.class.isAssignableFrom(valueType)) {
+                return NumberDeserializers.find(valueType) != null;
+            }
+            if ((valueType == CLASS_STRING)
+                    || (valueType == Boolean.class)
+                    || (valueType == EnumMap.class)
+                    || (valueType == AtomicReference.class)
+                    ) {
+                return true;
+            }
+            if (DateDeserializers.hasDeserializerFor(valueType)) {
+                return true;
+            }
+        } else if (clsName.startsWith("com.fasterxml.")) {
+            return JsonNode.class.isAssignableFrom(valueType)
+                   || (valueType == TokenBuffer.class);
+        } else {
+            return OptionalHandlerFactory.instance.hasDeserializerFor(valueType);
+        }
+        return false;
+    }
+
     private JavaType _findRemappedType(DeserializationConfig config, Class<?> rawType)
             throws JsonMappingException
     {

src/main/java/com/fasterxml/jackson/databind/deser/Deserializers.java

@@ -234,8 +234,21 @@ public JsonDeserializer<?> findMapLikeDeserializer(MapLikeType type,
             TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
         throws JsonMappingException;
 
-    // To be added in 3.0
-//    public boolean hasDeserializerFor(Class<?> valueType);
+    /**
+     * Method that may be called to check whether this deserializer provider would provide
+     * deserializer for values of given type, without attempting to construct (and possibly
+     * fail in some cases) actual deserializer. Mostly needed to support validation
+     * of polymorphic type ids.
+     *<p>
+     * Note: implementations should take care NOT to claim supporting types that they do
+     * not recognize as this could to incorrect assumption of safe support by caller.
+     *<p>
+     * Method added in this implementation since adding new methods for interfaces
+     * before Java 8 is not a good idea: will be added in Jackson 3.0 for `Deserializers`.
+     *
+     * @since 3.0
+     */
+    public boolean hasDeserializerFor(Class<?> valueType);
 
     /*
     /**********************************************************
@@ -333,23 +346,7 @@ public JsonDeserializer<?> findMapLikeDeserializer(MapLikeType type,
             return null;
         }
 
-        /**
-         * Method that may be called to check whether this deserializer provider would provide
-         * deserializer for values of given type, without attempting to construct (and possibly
-         * fail in some cases) actual deserializer. Mostly needed to support validation
-         * of polymorphic type ids.
-         *<p>
-         * Note: implementations should take care NOT to claim supporting types that they do
-         * not recognize as this could to incorrect assumption of safe support by caller.
-         *<p>
-         * Method added in this implementation since adding new methods for interfaces
-         * before Java 8 is not a good idea: will be added in Jackson 3.0 for `Deserializers`.
-         *
-         * @since 2.11
-         */
-        public boolean hasDeserializerFor(Class<?> valueType) {
-            return false;
-        }
-//      public abstract boolean hasDeserializerFor(Class<?> valueType);
+        @Override
+        public abstract boolean hasDeserializerFor(Class<?> valueType);
     }
 }

src/main/java/com/fasterxml/jackson/databind/deser/std/DateDeserializers.java

@@ -58,6 +58,10 @@ public static JsonDeserializer<?> find(Class<?> rawType, String clsName)
         return null;
     }
 
+    public static boolean hasDeserializerFor(Class<?> rawType) {
+        return _classNames.contains(rawType.getName());
+    }
+
     /*
     /**********************************************************
     /* Intermediate class for Date-based ones

src/main/java/com/fasterxml/jackson/databind/deser/std/NumberDeserializers.java

@@ -41,7 +41,7 @@ public class NumberDeserializers
         }
     }
 
-    public static JsonDeserializer<?> find(Class<?> rawType, String clsName) {
+    public static JsonDeserializer<?> find(Class<?> rawType) {
         if (rawType.isPrimitive()) {
             if (rawType == Integer.TYPE) {
                 return IntegerDeserializer.primitiveInstance;
@@ -67,7 +67,7 @@ public static JsonDeserializer<?> find(Class<?> rawType, String clsName) {
             if (rawType == Float.TYPE) {
                 return FloatDeserializer.primitiveInstance;
             }
-        } else if (_classNames.contains(clsName)) {
+        } else if (_classNames.contains(rawType.getName())) {
             // Start with most common types; int, boolean, long, double
             if (rawType == Integer.class) {
                 return IntegerDeserializer.wrapperInstance;

src/main/java/com/fasterxml/jackson/databind/ext/CoreXMLDeserializers.java

@@ -48,8 +48,7 @@ public static JsonDeserializer<?> findBeanDeserializer(DeserializationConfig con
         return null;
     }
 
-    @Override // since 2.11
-    public boolean hasDeserializerFor(Class<?> valueType) {
+    public static boolean hasDeserializerFor(Class<?> valueType) {
         return (valueType == QName.class)
                 || (valueType == XMLGregorianCalendar.class)
                 || (valueType == Duration.class)

src/main/java/com/fasterxml/jackson/databind/ext/OptionalHandlerFactory.java

@@ -76,6 +76,22 @@ public JsonDeserializer<?> findDeserializer(DeserializationConfig config, JavaTy
         return null;
     }
 
+    public boolean hasDeserializerFor(Class<?> valueType) {
+        if ((CLASS_DOM_NODE != null) && CLASS_DOM_NODE.isAssignableFrom(valueType)) {
+            return true;
+        }
+        if ((CLASS_DOM_DOCUMENT != null) && CLASS_DOM_DOCUMENT.isAssignableFrom(valueType)) {
+            return true;
+        }
+        String className = valueType.getName();
+
+        if (className.startsWith(PACKAGE_PREFIX_JAVAX_XML)
+                || hasSuperClassStartingWith(valueType, PACKAGE_PREFIX_JAVAX_XML)) {
+            return CoreXMLDeserializers.hasDeserializerFor(valueType);
+        }
+        return false;
+    }
+    
     /*
     /**********************************************************************
     /* Internal helper methods