DATAREDIS-713 - Introduce constants for commonly used StringSerializers.

We now provide constant StringSerializers for US-ASCII, ISO 8859-1 and UTF-8 encoding.

Original Pull Request: spring-projects#288

Author: mp911de

src/main/java/org/springframework/data/redis/cache/RedisCacheConfiguration.java

@@ -95,7 +95,7 @@ public static RedisCacheConfiguration defaultCacheConfig() {
 		registerDefaultConverters(conversionService);
 
 		return new RedisCacheConfiguration(Duration.ZERO, true, true, null,
-				SerializationPair.fromSerializer(new StringRedisSerializer()),
+				SerializationPair.fromSerializer(StringRedisSerializer.UTF_8),
 				SerializationPair.fromSerializer(new JdkSerializationRedisSerializer()), conversionService);
 	}
 

src/main/java/org/springframework/data/redis/connection/DefaultStringRedisConnection.java

@@ -117,7 +117,7 @@ public List<Object> convert(List<Object> execResults) {
 	 * @param connection Redis connection
 	 */
 	public DefaultStringRedisConnection(RedisConnection connection) {
-		this(connection, new StringRedisSerializer());
+		this(connection, StringRedisSerializer.UTF_8);
 	}
 
 	/**

src/main/java/org/springframework/data/redis/core/RedisTemplate.java

@@ -96,7 +96,7 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 	@SuppressWarnings("rawtypes") private @Nullable RedisSerializer valueSerializer = null;
 	@SuppressWarnings("rawtypes") private @Nullable RedisSerializer hashKeySerializer = null;
 	@SuppressWarnings("rawtypes") private @Nullable RedisSerializer hashValueSerializer = null;
-	private RedisSerializer<String> stringSerializer = new StringRedisSerializer();
+	private RedisSerializer<String> stringSerializer = StringRedisSerializer.UTF_8;
 
 	private @Nullable ScriptExecutor<K> scriptExecutor;
 

src/main/java/org/springframework/data/redis/core/StringRedisTemplate.java

@@ -31,6 +31,7 @@
  * {@link StringRedisConnection}.
  * 
  * @author Costin Leau
+ * @author Mark Paluch
  */
 public class StringRedisTemplate extends RedisTemplate<String, String> {
 
@@ -39,11 +40,10 @@ public class StringRedisTemplate extends RedisTemplate<String, String> {
 	 * and {@link #afterPropertiesSet()} still need to be called.
 	 */
 	public StringRedisTemplate() {
-		RedisSerializer<String> stringSerializer = new StringRedisSerializer();
-		setKeySerializer(stringSerializer);
-		setValueSerializer(stringSerializer);
-		setHashKeySerializer(stringSerializer);
-		setHashValueSerializer(stringSerializer);
+		setKeySerializer(StringRedisSerializer.UTF_8);
+		setValueSerializer(StringRedisSerializer.UTF_8);
+		setHashKeySerializer(StringRedisSerializer.UTF_8);
+		setHashValueSerializer(StringRedisSerializer.UTF_8);
 	}
 
 	/**

src/main/java/org/springframework/data/redis/listener/RedisMessageListenerContainer.java

@@ -127,7 +127,7 @@ public class RedisMessageListenerContainer implements InitializingBean, Disposab
 
 	private final SubscriptionTask subscriptionTask = new SubscriptionTask();
 
-	private volatile RedisSerializer<String> serializer = new StringRedisSerializer();
+	private volatile RedisSerializer<String> serializer = StringRedisSerializer.UTF_8;
 
 	private long recoveryInterval = DEFAULT_RECOVERY_INTERVAL;
 

src/main/java/org/springframework/data/redis/listener/adapter/MessageListenerAdapter.java

@@ -92,6 +92,7 @@
  * @author Greg Turnquist
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @see org.springframework.jms.listener.adapter.MessageListenerAdapter
  */
 public class MessageListenerAdapter implements InitializingBean, MessageListener {
@@ -317,9 +318,8 @@ public void onMessage(Message message, @Nullable byte[] pattern) {
 	 * @see JdkSerializationRedisSerializer
 	 */
 	protected void initDefaultStrategies() {
-		RedisSerializer<String> serializer = new StringRedisSerializer();
-		setSerializer(serializer);
-		setStringSerializer(serializer);
+		setSerializer(StringRedisSerializer.UTF_8);
+		setStringSerializer(StringRedisSerializer.UTF_8);
 	}
 
 	/**

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

@@ -98,7 +98,7 @@ static class DefaultRedisSerializationContextBuilder<K, V> implements RedisSeria
 		private @Nullable SerializationPair<V> valueTuple;
 		private @Nullable SerializationPair<?> hashKeyTuple;
 		private @Nullable SerializationPair<?> hashValueTuple;
-		private SerializationPair<String> stringTuple = SerializationPair.fromSerializer(new StringRedisSerializer());
+		private SerializationPair<String> stringTuple = SerializationPair.fromSerializer(StringRedisSerializer.UTF_8);
 
 		/* (non-Javadoc)
 		 * @see org.springframework.data.redis.serializer.RedisSerializationContextBuilder#key(SerializationPair)

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

@@ -93,7 +93,7 @@ static RedisSerializationContext<byte[], byte[]> raw() {
 	 * @return
 	 */
 	static RedisSerializationContext<String, String> string() {
-		return fromSerializer(new StringRedisSerializer());
+		return fromSerializer(StringRedisSerializer.UTF_8);
 	}
 
 	/**

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

@@ -22,20 +22,42 @@
 import org.springframework.util.Assert;
 
 /**
- * Simple String to byte[] (and back) serializer. Converts Strings into bytes and vice-versa using the specified charset
- * (by default UTF-8).
+ * Simple {@literal} to {@literal byte[]} (and back) serializer. Converts Strings into bytes and vice-versa using the
+ * specified charset (by default UTF-8).
  * <p>
  * Useful when the interaction with the Redis happens mainly through Strings.
  * <p>
- * Does not perform any null conversion since empty strings are valid keys/values.
+ * Does not perform any {@literal null} conversion since empty strings are valid keys/values.
  *
  * @author Costin Leau
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public class StringRedisSerializer implements RedisSerializer<String> {
 
 	private final Charset charset;
 
+	/**
+	 * Serializer to use 7 bit ASCII, a.k.a. ISO646-US, a.k.a. the Basic Latin block of the Unicode character set.
+	 * 
+	 * @since 2.1
+	 */
+	public static final StringRedisSerializer US_ASCII = new StringRedisSerializer(StandardCharsets.US_ASCII);
+
+	/**
+	 * Serializer to use ISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1.
+	 * 
+	 * @since 2.1
+	 */
+	public static final StringRedisSerializer ISO_8859_1 = new StringRedisSerializer(StandardCharsets.ISO_8859_1);
+
+	/**
+	 * Serializer to use 8 bit UCS Transformation Format.
+	 * 
+	 * @since 2.1
+	 */
+	public static final StringRedisSerializer UTF_8 = new StringRedisSerializer(StandardCharsets.UTF_8);
+
 	/**
 	 * Creates a new {@link StringRedisSerializer} using {@link StandardCharsets#UTF_8 UTF-8}.
 	 */

src/main/java/org/springframework/data/redis/support/atomic/RedisAtomicDouble.java

@@ -79,7 +79,7 @@ private RedisAtomicDouble(String redisCounter, RedisConnectionFactory factory, @
 		Assert.notNull(factory, "a valid factory is required");
 
 		RedisTemplate<String, Double> redisTemplate = new RedisTemplate<>();
-		redisTemplate.setKeySerializer(new StringRedisSerializer());
+		redisTemplate.setKeySerializer(StringRedisSerializer.UTF_8);
 		redisTemplate.setValueSerializer(new GenericToStringSerializer<>(Double.class));
 		redisTemplate.setExposeConnection(true);
 		redisTemplate.setConnectionFactory(factory);