DATAREDIS-392 - Add Gerneric Jackson2 RedisSerializer.

We introduced GenericJackson2JsonRedisSerializer holding a preconfigured ObjectMapper which writes Class type informations into the JSON structure. This enables polymorphic deserialization and allows RedisCache manager to operate upon a RedisTemplate storing data in JSON format, which had until this only been possible using the Jdk Serializer.

src/main/java/org/springframework/data/redis/serializer/GenericJackson2JsonRedisSerializer.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright 2015 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 org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.annotation.JsonTypeInfo.As;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectMapper.DefaultTyping;
+import com.fasterxml.jackson.databind.ser.SerializerFactory;
+
+/**
+ * @author Christoph Strobl
+ * @since 1.6
+ */
+public class GenericJackson2JsonRedisSerializer implements RedisSerializer<Object> {
+
+	private final ObjectMapper mapper;
+
+	/**
+	 * Creates {@link GenericJackson2JsonRedisSerializer} and configures {@link ObjectMapper} for default typing.
+	 */
+	public GenericJackson2JsonRedisSerializer() {
+		this((String) null);
+	}
+
+	/**
+	 * Creates {@link GenericJackson2JsonRedisSerializer} and configures {@link ObjectMapper} for default typing using the
+	 * given {@literal name}. In case of an {@literal empty} or {@literal null} String the default
+	 * {@link JsonTypeInfo.Id#CLASS} will be used.
+	 * 
+	 * @param classPropertyTypeName Name of the JSON property holding type information. Can be {@literal null}.
+	 */
+	public GenericJackson2JsonRedisSerializer(String classPropertyTypeName) {
+
+		this(new ObjectMapper());
+
+		if (StringUtils.hasText(classPropertyTypeName)) {
+			mapper.enableDefaultTypingAsProperty(DefaultTyping.NON_FINAL, classPropertyTypeName);
+		} else {
+			mapper.enableDefaultTyping(DefaultTyping.NON_FINAL, As.PROPERTY);
+		}
+	}
+
+	/**
+	 * Setting a custom-configured {@link 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.
+	 * 
+	 * @param mapper must not be {@literal null}.
+	 */
+	public GenericJackson2JsonRedisSerializer(ObjectMapper mapper) {
+
+		Assert.notNull(mapper, "ObjectMapper must not be null!");
+		this.mapper = mapper;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.serializer.RedisSerializer#serialize(java.lang.Object)
+	 */
+	@Override
+	public byte[] serialize(Object source) throws SerializationException {
+
+		if (source == null) {
+			return SerializationUtils.EMPTY_ARRAY;
+		}
+
+		try {
+			return mapper.writeValueAsBytes(source);
+		} catch (JsonProcessingException e) {
+			throw new SerializationException("Could not write JSON: " + e.getMessage(), e);
+		}
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.serializer.RedisSerializer#deserialize(byte[])
+	 */
+	@Override
+	public Object deserialize(byte[] source) throws SerializationException {
+		return deserialize(source, Object.class);
+	}
+
+	/**
+	 * @param source can be {@literal null}.
+	 * @param type must not be {@literal null}.
+	 * @return {@literal null} for empty source.
+	 * @throws SerializationException
+	 */
+	public <T> T deserialize(byte[] source, Class<T> type) throws SerializationException {
+
+		Assert.notNull(type,
+				"Deserialization type must not be null! Pleaes provide Object.class to make use of Jackson2 default typing.");
+
+		if (SerializationUtils.isEmpty(source)) {
+			return null;
+		}
+
+		try {
+			return mapper.readValue(source, type);
+		} catch (Exception ex) {
+			throw new SerializationException("Could not read JSON: " + ex.getMessage(), ex);
+		}
+	}
+}