DATAREDIS-241 - Add a Jackson2 based RedisSerializer.

Introduced Jackson2JsonRedisSerializer and added optional dependency for Jackson2 core/databind (fasterxml) library.
Added additional parameterised test cases. Needed to increase the max active connections limit for the connection pools used in RedisMapTests.

src/main/java/org/springframework/data/redis/serializer/Jackson2JsonRedisSerializer.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2011-2014 the original author or authors.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.redis.serializer;
+
+import java.nio.charset.Charset;
+
+import org.springframework.util.Assert;
+
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ser.SerializerFactory;
+import com.fasterxml.jackson.databind.type.TypeFactory;
+
+/**
+ * {@link RedisSerializer} that can read and write JSON using <a
+ * href="https://github.com/FasterXML/jackson-core">Jackson's</a> and <a
+ * href="https://github.com/FasterXML/jackson-databind">Jackson Databind<a> {@link ObjectMapper}.
+ * <p>
+ * This converter can be used to bind to typed beans, or untyped {@link java.util.HashMap HashMap} instances.
+ * <b>Note:</b>Null objects are serialized as empty arrays and vice versa.
+ * 
+ * @author Thomas Darimont
+ * @since 1.2
+ */
+public class Jackson2JsonRedisSerializer<T> implements RedisSerializer<T> {
+
+	public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
+
+	private final JavaType javaType;
+
+	private ObjectMapper objectMapper = new ObjectMapper();
+
+	public Jackson2JsonRedisSerializer(Class<T> type) {
+		this.javaType = TypeFactory.defaultInstance().constructType(type);
+	}
+
+	@SuppressWarnings("unchecked")
+	public T deserialize(byte[] bytes) throws SerializationException {
+		
+		if (SerializationUtils.isEmpty(bytes)) {
+			return null;
+		}
+		try {
+			return (T) this.objectMapper.readValue(bytes, 0, bytes.length, javaType);
+		} catch (Exception ex) {
+			throw new SerializationException("Could not read JSON: " + ex.getMessage(), ex);
+		}
+	}
+
+	public byte[] serialize(Object t) throws SerializationException {
+		
+		if (t == null) {
+			return SerializationUtils.EMPTY_ARRAY;
+		}
+		try {
+			return this.objectMapper.writeValueAsBytes(t);
+		} catch (Exception ex) {
+			throw new SerializationException("Could not write JSON: " + ex.getMessage(), ex);
+		}
+	}
+
+	/**
+	 * Sets the {@code ObjectMapper} for this view. If not set, a default {@link ObjectMapper#ObjectMapper() ObjectMapper}
+	 * is used.
+	 * <p>
+	 * Setting a custom-configured {@code ObjectMapper} is one way to take further control of the JSON serialization
+	 * process. For example, an extended {@link SerializerFactory} can be configured that provides custom serializers for
+	 * specific types. The other option for refining the serialization process is to use Jackson's provided annotations on
+	 * the types to be serialized, in which case a custom-configured ObjectMapper is unnecessary.
+	 */
+	public void setObjectMapper(ObjectMapper objectMapper) {
+		
+		Assert.notNull(objectMapper, "'objectMapper' must not be null");
+		this.objectMapper = objectMapper;
+	}
+
+	/**
+	 * Returns the Jackson {@link JavaType} for the specific class.
+	 * <p>
+	 * Default implementation returns {@link TypeFactory#constructType(java.lang.reflect.Type)}, but this can be
+	 * overridden in subclasses, to allow for custom generic collection handling. For instance:
+	 * 
+	 * <pre class="code">
+	 * protected JavaType getJavaType(Class&lt;?&gt; clazz) {
+	 * 	if (List.class.isAssignableFrom(clazz)) {
+	 * 		return TypeFactory.defaultInstance().constructCollectionType(ArrayList.class, MyBean.class);
+	 * 	} else {
+	 * 		return super.getJavaType(clazz);
+	 * 	}
+	 * }
+	 * </pre>
+	 * 
+	 * @param clazz the class to return the java type for
+	 * @return the java type
+	 */
+	protected JavaType getJavaType(Class<?> clazz) {
+		return TypeFactory.defaultInstance().constructType(clazz);
+	}
+}