+ add append and substract operations

spring-data-redis/src/main/java/org/springframework/data/keyvalue/redis/connection/RedisStringCommands.java

@@ -52,5 +52,5 @@ public interface RedisStringCommands {
 
 	Long append(byte[] key, byte[] value);
 
-	byte[] substr(byte[] key, long start, long end);
+	byte[] substr(byte[] key, int start, int end);
 }

spring-data-redis/src/main/java/org/springframework/data/keyvalue/redis/connection/jedis/JedisConnection.java

@@ -499,7 +499,7 @@ public class JedisConnection implements RedisConnection {
 	}
 
 	@Override
-	public byte[] substr(byte[] key, long start, long end) {
+	public byte[] substr(byte[] key, int start, int end) {
 		try {
 			if (isQueueing()) {
 				transaction.substr(key, (int) start, (int) end);

spring-data-redis/src/main/java/org/springframework/data/keyvalue/redis/connection/jredis/JredisConnection.java

@@ -330,7 +330,7 @@ public class JredisConnection implements RedisConnection {
 	}
 
 	@Override
-	public byte[] substr(byte[] key, long start, long end) {
+	public byte[] substr(byte[] key, int start, int end) {
 		try {
 			return jredis.substr(JredisUtils.decode(key), start, end);
 		} catch (RedisException ex) {

spring-data-redis/src/main/java/org/springframework/data/keyvalue/redis/core/BoundValueOperations.java

@@ -38,4 +38,8 @@ public interface BoundValueOperations<K, V> extends KeyBound<K> {
 
 	Long increment(long delta);
 
+	Integer append(String value);
+
+	String substract(int start, int end);
+
 }

spring-data-redis/src/main/java/org/springframework/data/keyvalue/redis/core/DefaultBoundValueOperations.java

@@ -50,6 +50,16 @@ class DefaultBoundValueOperations<K, V> extends DefaultKeyBound<K> implements Bo
 		return ops.increment(getKey(), delta);
 	}
 
+	@Override
+	public Integer append(String value) {
+		return ops.append(getKey(), value);
+	}
+
+	@Override
+	public String substract(int start, int end) {
+		return ops.substract(getKey(), start, end);
+	}
+
 	@Override
 	public void set(V value, long timeout, TimeUnit unit) {
 		ops.set(getKey(), value, timeout, unit);

spring-data-redis/src/main/java/org/springframework/data/keyvalue/redis/core/RedisTemplate.java

@@ -71,6 +71,7 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 	private RedisSerializer valueSerializer = new SimpleRedisSerializer();
 	private RedisSerializer hashKeySerializer = new SimpleRedisSerializer();
 	private RedisSerializer hashValueSerializer = new SimpleRedisSerializer();
+	private RedisSerializer stringSerializer = new StringRedisSerializer();
 
 	// cache singleton objects (where possible)
 	private final ValueOperations<K, V> valueOps = new DefaultValueOperations();
@@ -205,6 +206,16 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 		this.hashValueSerializer = hashValueSerializer;
 	}
 
+	/**
+	 * Sets the string value serializer to be used by this template (when the arguments or return types
+	 * are always strings). Defaults to {@link StringRedisSerializer}.
+	 * 
+	 * @see ValueOperations#substract(Object, int, int)
+	 * @param stringSerializer The stringValueSerializer to set.
+	 */
+	public void setStringSerializer(RedisSerializer<?> stringSerializer) {
+		this.stringSerializer = stringSerializer;
+	}
 
 	/**
 	 * Invocation handler that suppresses close calls on JDO PersistenceManagers.
@@ -250,6 +261,11 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 		return (key != null ? keySerializer.serialize(key) : null);
 	}
 
+	@SuppressWarnings("unchecked")
+	private byte[] rawString(String key) {
+		return (key != null ? stringSerializer.serialize(key) : null);
+	}
+
 	@SuppressWarnings("unchecked")
 	private <T> byte[] rawValue(T value) {
 		return (value != null ? valueSerializer.serialize(value) : null);
@@ -339,6 +355,11 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 		return (V) deserialize(value, valueSerializer);
 	}
 
+	@SuppressWarnings("unchecked")
+	private String deserializeString(byte[] value) {
+		return (String) deserialize(value, stringSerializer);
+	}
+
 	@SuppressWarnings( { "unchecked", "unused" })
 	private <HK> HK deserializeHashKey(byte[] value) {
 		return (HK) deserialize(value, hashKeySerializer);
@@ -356,6 +377,7 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 		return serializer.deserialize(value);
 	}
 
+
 	private static boolean isEmpty(byte[] data) {
 		return (data == null || data.length == 0);
 	}
@@ -676,6 +698,33 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 			}, true);
 		}
 
+		@Override
+		public Integer append(K key, String value) {
+			final byte[] rawKey = rawKey(key);
+			final byte[] rawString = rawString(value);
+
+			return execute(new RedisCallback<Integer>() {
+				@Override
+				public Integer doInRedis(RedisConnection connection) {
+					return connection.append(rawKey, rawString).intValue();
+				}
+			}, true);
+		}
+
+		@Override
+		public String substract(K key, final int start, final int end) {
+			final byte[] rawKey = rawKey(key);
+
+			byte[] rawReturn = execute(new RedisCallback<byte[]>() {
+				@Override
+				public byte[] doInRedis(RedisConnection connection) {
+					return connection.substr(rawKey, start, end);
+				}
+			}, true);
+
+			return deserializeString(rawReturn);
+		}
+
 		@Override
 		public Collection<V> multiGet(Collection<K> keys) {
 			if (keys.isEmpty()) {

spring-data-redis/src/main/java/org/springframework/data/keyvalue/redis/core/ValueOperations.java

@@ -44,5 +44,9 @@ public interface ValueOperations<K, V> {
 
 	Long increment(K key, long delta);
 
+	Integer append(K key, String value);
+
+	String substract(K key, int start, int end);
+
 	RedisOperations<K, V> getOperations();
 }