Add support for Jackson 3-based HashMapper and RedisSerializer.

We now support Jackson 3 through a separate Jackson3HashMapper, Jackson3JsonRedisSerializer, and GenericJackson3JsonRedisSerializer.

Jackson 3 uses different defaults than Jackson 2 did therefore, we also provide configuration variants that reflect Jackson 2 behavior for smoother upgrade paths.

Original pull request: #3168
Closes #3154

Author: christophstrobl

pom.xml

@@ -149,6 +149,20 @@
 			<optional>true</optional>
 		</dependency>
 
+		<!-- jackson 3 -->
+		<dependency>
+			<groupId>tools.jackson.core</groupId>
+			<artifactId>jackson-databind</artifactId>
+			<optional>true</optional>
+		</dependency>
+
+		<dependency>
+			<groupId>com.fasterxml.jackson.core</groupId>
+			<artifactId>jackson-annotations</artifactId>
+			<version>3.0-rc5</version>
+			<optional>true</optional>
+		</dependency>
+
 		<dependency>
 			<groupId>commons-beanutils</groupId>
 			<artifactId>commons-beanutils</artifactId>

src/main/antora/modules/ROOT/pages/redis/hash-mappers.adoc

@@ -1,7 +1,7 @@
 [[redis.hashmappers.root]]
 = Hash Mapping
 
-Data can be stored by using various data structures within Redis. javadoc:org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer[] can convert objects in https://en.wikipedia.org/wiki/JSON[JSON] format. Ideally, JSON can be stored as a value by using plain keys. You can achieve a more sophisticated mapping of structured objects by using Redis hashes. Spring Data Redis offers various strategies for mapping data to hashes (depending on the use case):
+Data can be stored by using various data structures within Redis. javadoc:org.springframework.data.redis.serializer.Jackson3JsonRedisSerializer[] can convert objects in https://en.wikipedia.org/wiki/JSON[JSON] format. Ideally, JSON can be stored as a value by using plain keys. You can achieve a more sophisticated mapping of structured objects by using Redis hashes. Spring Data Redis offers various strategies for mapping data to hashes (depending on the use case):
 
 * Direct mapping, by using javadoc:org.springframework.data.redis.core.HashOperations[] and a xref:redis.adoc#redis:serializer[serializer]
 * Using xref:repositories.adoc[Redis Repositories]
@@ -16,7 +16,8 @@ Multiple implementations are available:
 
 * javadoc:org.springframework.data.redis.hash.BeanUtilsHashMapper[] using Spring's {spring-framework-javadoc}/org/springframework/beans/BeanUtils.html[BeanUtils].
 * javadoc:org.springframework.data.redis.hash.ObjectHashMapper[] using xref:redis/redis-repositories/mapping.adoc[Object-to-Hash Mapping].
-* <<redis.hashmappers.jackson2,`Jackson2HashMapper`>> using https://github.com/FasterXML/jackson[FasterXML Jackson].
+* <<redis.hashmappers.jackson3,`Jackson3HashMapper`>> using https://github.com/FasterXML/jackson[FasterXML Jackson 3].
+* <<redis.hashmappers.jackson2,`Jackson2HashMapper`>> (deprecated) using https://github.com/FasterXML/jackson[FasterXML Jackson 2].
 
 The following example shows one way to implement hash mapping:
 
@@ -50,9 +51,91 @@ public class HashMapping {
 }
 ----
 
+[[redis.hashmappers.jackson3]]
+=== Jackson3HashMapper
+
+javadoc:org.springframework.data.redis.hash.Jackson3HashMapper[] provides Redis Hash mapping for domain objects by using https://github.com/FasterXML/jackson[FasterXML Jackson 3].
+`Jackson3HashMapper` can map top-level properties as Hash field names and, optionally, flatten the structure.
+Simple types map to simple values. Complex types (nested objects, collections, maps, and so on) are represented as nested JSON.
+
+Flattening creates individual hash entries for all nested properties and resolves complex types into simple types, as far as possible.
+
+Consider the following class and the data structure it contains:
+
+[source,java]
+----
+public class Person {
+  String firstname;
+  String lastname;
+  Address address;
+  Date date;
+  LocalDateTime localDateTime;
+}
+
+public class Address {
+  String city;
+  String country;
+}
+----
+
+The following table shows how the data in the preceding class would appear in normal mapping:
+
+.Normal Mapping
+[width="80%",cols="<1,<2",options="header"]
+|====
+|Hash Field
+|Value
+
+|firstname
+|`Jon`
+
+|lastname
+|`Snow`
+
+|address
+|`{ "city" : "Castle Black", "country" : "The North" }`
+
+|date
+|1561543964015
+
+|localDateTime
+|`2018-01-02T12:13:14`
+|====
+
+The following table shows how the data in the preceding class would appear in flat mapping:
+
+.Flat Mapping
+[width="80%",cols="<1,<2",options="header"]
+|====
+|Hash Field
+|Value
+
+|firstname
+|`Jon`
+
+|lastname
+|`Snow`
+
+|address.city
+|`Castle Black`
+
+|address.country
+|`The North`
+
+|date
+|1561543964015
+
+|localDateTime
+|`2018-01-02T12:13:14`
+|====
+
+NOTE: Flattening requires all property names to not interfere with the JSON path. Using dots or brackets in map keys or as property names is not supported when you use flattening. The resulting hash cannot be mapped back into an Object.
+
 [[redis.hashmappers.jackson2]]
 === Jackson2HashMapper
 
+WARNING: Jackson 2 based implementations have been deprecated and are subject to removal in a subsequent release.
+
 javadoc:org.springframework.data.redis.hash.Jackson2HashMapper[] provides Redis Hash mapping for domain objects by using https://github.com/FasterXML/jackson[FasterXML Jackson].
 `Jackson2HashMapper` can map top-level properties as Hash field names and, optionally, flatten the structure.
 Simple types map to simple values. Complex types (nested objects, collections, maps, and so on) are represented as nested JSON.

src/main/antora/modules/ROOT/pages/redis/redis-repositories/mapping.adoc

@@ -92,11 +92,11 @@ The following example shows two sample byte array converters:
 @WritingConverter
 public class AddressToBytesConverter implements Converter<Address, byte[]> {
 
-  private final Jackson2JsonRedisSerializer<Address> serializer;
+  private final Jackson3JsonRedisSerializer<Address> serializer;
 
   public AddressToBytesConverter() {
 
-    serializer = new Jackson2JsonRedisSerializer<Address>(Address.class);
+    serializer = new Jackson3JsonRedisSerializer<Address>(Address.class);
     serializer.setObjectMapper(new ObjectMapper());
   }
 
@@ -109,11 +109,11 @@ public class AddressToBytesConverter implements Converter<Address, byte[]> {
 @ReadingConverter
 public class BytesToAddressConverter implements Converter<byte[], Address> {
 
-  private final Jackson2JsonRedisSerializer<Address> serializer;
+  private final Jackson3JsonRedisSerializer<Address> serializer;
 
   public BytesToAddressConverter() {
 
-    serializer = new Jackson2JsonRedisSerializer<Address>(Address.class);
+    serializer = new Jackson3JsonRedisSerializer<Address>(Address.class);
     serializer.setObjectMapper(new ObjectMapper());
   }
 

src/main/antora/modules/ROOT/pages/redis/redis-streams.adoc

@@ -291,7 +291,7 @@ You may provide a `HashMapper` suitable for your requirements when obtaining `St
 [source,java]
 ----
 redisTemplate()
-    .opsForStream(new Jackson2HashMapper(true))
+    .opsForStream(new Jackson3HashMapper(true))
     .add(record); <1>
 ----
 <1> XADD user-logon * "firstname" "night" "@class" "com.example.User" "lastname" "angel"

src/main/antora/modules/ROOT/pages/redis/template.adoc

@@ -365,7 +365,7 @@ Multiple implementations are available (including two that have been already men
 * javadoc:org.springframework.data.redis.serializer.JdkSerializationRedisSerializer[], which is used by default for javadoc:org.springframework.data.redis.cache.RedisCache[] and javadoc:org.springframework.data.redis.core.RedisTemplate[].
 * the `StringRedisSerializer`.
 
-However, one can use `OxmSerializer` for Object/XML mapping through Spring {spring-framework-docs}/data-access.html#oxm[OXM] support or javadoc:org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer[] or javadoc:org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer[] for storing data in https://en.wikipedia.org/wiki/JSON[JSON] format.
+However, one can use `OxmSerializer` for Object/XML mapping through Spring {spring-framework-docs}/data-access.html#oxm[OXM] support or javadoc:org.springframework.data.redis.serializer.Jackson3JsonRedisSerializer[] or javadoc:org.springframework.data.redis.serializer.GenericJackson3JsonRedisSerializer[] for storing data in https://en.wikipedia.org/wiki/JSON[JSON] format.
 
 Do note that the storage format is not limited only to values.
 It can be used for keys, values, or hashes without any restrictions.

src/main/java/org/springframework/data/redis/hash/Jackson2HashMapper.java

@@ -143,7 +143,9 @@
  * @author Mark Paluch
  * @author John Blum
  * @since 1.8
+ * @deprecated since 4.0
  */
+@Deprecated(since = "4.0", forRemoval = true)
 public class Jackson2HashMapper implements HashMapper<Object, String, Object> {
 
 	private static final boolean SOURCE_VERSION_PRESENT =