Fixed EsotericSoftware#180. Added support for field annotations.

src/com/esotericsoftware/kryo/serializers/CollectionSerializer.java

@@ -1,6 +1,10 @@
 
 package com.esotericsoftware.kryo.serializers;
 
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
 import java.util.ArrayList;
 import java.util.Collection;
 
@@ -127,4 +131,34 @@ public Collection copy (Kryo kryo, Collection original) {
 			copy.add(kryo.copy(element));
 		return copy;
 	}
+
+	/**
+	 * Used to annotate fields that are collections with specific Kryo serializers
+	 * for their values.
+	 */
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target(ElementType.FIELD)
+	public @interface BindKryoSerializer {
+	    /**
+	     * Serializer to be used for values
+	     * 
+	     * @return the class<? extends Serializer> used for values serialization
+	     */
+	    @SuppressWarnings("rawtypes")
+	    Class<? extends Serializer> elementSerializer() default Serializer.class;
+
+	    /**
+	     * Class used for elements
+	     * 
+	     * @return the class used for elements
+	     */
+	    Class<?> elementClass() default Object.class;
+
+	    /**
+	     * Indicates if elements can be null
+	     * 
+	     * @return true, if elements can be null
+	     */
+	    boolean elementsCanBeNull() default true;
+	}
 }

src/com/esotericsoftware/kryo/serializers/FieldSerializer.java

@@ -14,6 +14,7 @@
 import java.security.AccessControlException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
@@ -26,6 +27,7 @@
 import com.esotericsoftware.kryo.NotNull;
 import com.esotericsoftware.kryo.Registration;
 import com.esotericsoftware.kryo.Serializer;
+import com.esotericsoftware.kryo.factories.ReflectionSerializerFactory;
 import com.esotericsoftware.kryo.io.Input;
 import com.esotericsoftware.kryo.io.Output;
 import com.esotericsoftware.kryo.util.IntArray;
@@ -224,6 +226,102 @@ protected void rebuildCachedFields () {
 
 		for (String fieldName : removedFields.keySet())
 			removeField(fieldName);
+
+		processAnnotatedFields();
+	}
+
+	/**
+	 * Process annotated fields and set serializers according to the 
+	 * provided annotation.
+	 * 
+	 * @see BindKryoSerializer
+	 * @see CollectionSerializer.BindKryoSerializer
+	 * @see MapSerializer.BindKryoSerializer
+	 */
+	protected void processAnnotatedFields () {
+		for (int i = 0, n = fields.length; i < n; i++) {
+			Field field = fields[i].getField();
+
+			// Set a specific serializer for a particular field
+			if (field.isAnnotationPresent(FieldSerializer.BindKryoSerializer.class)) {
+				Class<? extends Serializer> serializerClass = field.getAnnotation(FieldSerializer.BindKryoSerializer.class).value();
+				Serializer s = ReflectionSerializerFactory.makeSerializer(this.getKryo(), serializerClass, field.getClass());
+				fields[i].setSerializer(s);
+			}
+
+			if (field.isAnnotationPresent(CollectionSerializer.BindKryoSerializer.class)
+				&& field.isAnnotationPresent(MapSerializer.BindKryoSerializer.class)) {
+
+			}
+			// Set a specific collection serializer for a particular field
+			if (field.isAnnotationPresent(CollectionSerializer.BindKryoSerializer.class)) {
+				if (fields[i].serializer != null)
+					throw new RuntimeException("CollectionSerialier.BindKryoSerializer cannot be used with field "
+						+ fields[i].getField().getDeclaringClass().getName() + "." + fields[i].getField().getName()
+						+ ", because it has a serializer already.");
+				CollectionSerializer.BindKryoSerializer annotation = field
+					.getAnnotation(CollectionSerializer.BindKryoSerializer.class);
+				if (Collection.class.isAssignableFrom(fields[i].field.getType())) {
+					Class<? extends Serializer> elementSerializerClass = annotation.elementSerializer();
+					if (elementSerializerClass == Serializer.class) elementSerializerClass = null;
+					Serializer elementSerializer = (elementSerializerClass == null) ? null : ReflectionSerializerFactory
+						.makeSerializer(this.getKryo(), elementSerializerClass, field.getClass());
+					boolean elementsCanBeNull = annotation.elementsCanBeNull();
+					Class<?> elementClass = annotation.elementClass();
+					if (elementClass == Object.class) elementClass = null;
+					CollectionSerializer serializer = new CollectionSerializer();
+					serializer.setElementsCanBeNull(elementsCanBeNull);
+					serializer.setElementClass(elementClass, elementSerializer);
+					fields[i].setSerializer(serializer);
+				} else {
+					throw new RuntimeException(
+						"CollectionSerialier.BindKryoSerializer should be used only with fields implementing java.util.Collection, but field "
+							+ fields[i].getField().getDeclaringClass().getName() + "." + fields[i].getField().getName()
+							+ " does not implement it.");
+				}
+			}
+
+			// Set a specific map serializer for a particular field
+			if (field.isAnnotationPresent(MapSerializer.BindKryoSerializer.class)) {
+				if (fields[i].serializer != null)
+					throw new RuntimeException("MapSerialier.BindKryoSerializer cannot be used with field "
+						+ fields[i].getField().getDeclaringClass().getName() + "." + fields[i].getField().getName()
+						+ ", because it has a serializer already.");
+				MapSerializer.BindKryoSerializer annotation = field.getAnnotation(MapSerializer.BindKryoSerializer.class);
+				if (Map.class.isAssignableFrom(fields[i].field.getType())) {
+					Class<? extends Serializer> valueSerializerClass = annotation.valueSerializer();
+					Class<? extends Serializer> keySerializerClass = annotation.keySerializer();
+
+					if (valueSerializerClass == Serializer.class) valueSerializerClass = null;
+					if (keySerializerClass == Serializer.class) keySerializerClass = null;
+
+					Serializer valueSerializer = (valueSerializerClass == null) ? null : ReflectionSerializerFactory.makeSerializer(
+						this.getKryo(), valueSerializerClass, field.getClass());
+					Serializer keySerializer = (keySerializerClass == null) ? null : ReflectionSerializerFactory.makeSerializer(
+						this.getKryo(), keySerializerClass, field.getClass());
+					boolean valuesCanBeNull = annotation.valuesCanBeNull();
+					boolean keysCanBeNull = annotation.keysCanBeNull();
+					Class<?> keyClass = annotation.keyClass();
+					Class<?> valueClass = annotation.valueClass();
+
+					if (keyClass == Object.class) keyClass = null;
+					if (valueClass == Object.class) valueClass = null;
+
+					MapSerializer serializer = new MapSerializer();
+					serializer.setKeysCanBeNull(keysCanBeNull);
+					serializer.setValuesCanBeNull(valuesCanBeNull);
+					serializer.setKeyClass(keyClass, keySerializer);
+					serializer.setValueClass(valueClass, valueSerializer);
+					fields[i].setSerializer(serializer);
+				} else {
+					throw new RuntimeException(
+						"MapSerialier.BindKryoSerializer should be used only with fields implementing java.util.Map, but field "
+							+ fields[i].getField().getDeclaringClass().getName() + "." + fields[i].getField().getName()
+							+ " does not implement it.");
+				}
+			}
+
+		}
 	}
 
 	private List<Field> buildValidFields (boolean transientFields, List<Field> allFields, ObjectMap context, IntArray useAsm) {
@@ -524,10 +622,14 @@ public void removeField (String fieldName) {
 		throw new IllegalArgumentException("Field \"" + fieldName + "\" not found on class: " + type.getName());
 	}
 
+	/**
+	 * Get all fields controlled by this FieldSerializer 
+	 * @return all fields controlled by this FieldSerializer
+	 */
 	public CachedField[] getFields () {
 		return fields;
 	}
-
+	
 	public Class getType () {
 		return type;
 	}
@@ -603,6 +705,10 @@ public void setClass (Class valueClass, Serializer serializer) {
 		public void setSerializer (Serializer serializer) {
 			this.serializer = serializer;
 		}
+
+		public Serializer getSerializer() {
+			return this.serializer;
+		}
 
 		public void setCanBeNull (boolean canBeNull) {
 			this.canBeNull = canBeNull;
@@ -637,4 +743,21 @@ public static interface CachedFieldFactory {
 	static public @interface Optional {
 		public String value();
 	}
+
+	/**
+	 * Used to annotate fields with a specific Kryo serializer.
+	 */
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target(ElementType.FIELD)
+	public @interface BindKryoSerializer {
+
+	    /**
+	     * Value.
+	     * 
+	     * @return the class<? extends serializer> used for this field
+	     */
+	    @SuppressWarnings("rawtypes")
+	    Class<? extends Serializer> value();
+
+	}
 }

src/com/esotericsoftware/kryo/serializers/MapSerializer.java

@@ -1,6 +1,10 @@
 
 package com.esotericsoftware.kryo.serializers;
 
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -154,4 +158,57 @@ public Map copy (Kryo kryo, Map original) {
 		}
 		return copy;
 	}
+
+	/** 
+	 * Used to annotate fields that are maps with specific Kryo serializers for 
+	 * their keys or values. 
+	 */
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target(ElementType.FIELD)
+	public @interface BindKryoSerializer {
+
+		/** 
+		 * Serializer to be used for keys
+		 * 
+		 * @return the class<? extends serializer> used for keys serialization
+		 */
+		@SuppressWarnings("rawtypes")
+		Class<? extends Serializer> keySerializer() default Serializer.class;
+
+		/** 
+		 * Serializer to be used for values
+		 * 
+		 * @return the class<? extends serializer> used for values serialization 
+		 */
+		@SuppressWarnings("rawtypes")
+		Class<? extends Serializer> valueSerializer() default Serializer.class;
+
+		/** 
+		 * Class used for keys
+		 * 
+		 * @return the class used for keys 
+		 */
+		Class<?> keyClass() default Object.class;
+
+		/** 
+		 * Class used for values
+		 * 
+		 * @return the class used for values 
+		 */
+		Class<?> valueClass() default Object.class;
+
+		/** 
+		 * Indicates if keys can be null
+		 * 
+		 * @return true, if keys can be null 
+		 */
+		boolean keysCanBeNull() default true;
+
+		/** 
+		 * Indicates if values can be null
+		 * 
+		 * @return true, if values can be null 
+		 */
+		boolean valuesCanBeNull() default true;
+	}
 }