Updates Jackson usage to use immutable ObjectReader/Writer instead of ObjectMapper

Jackson 2.10+ recommend using `ObjectReader` and `ObjectWriter` as opposed to `ObjectMapper`
https://cowtowncoder.medium.com/jackson-3-0-immutability-w-builders-d9c532860d88

Author: bdemers

CHANGELOG.md

@@ -5,7 +5,8 @@
 This patch release:
 
 * Adds additional handling for rare JSON parsing exceptions and wraps them in a `JwtException` to allow the application to handle these conditions as JWT concerns.
-* Upgrades the `jjwt-jackson` module's Jackson dependency to `2.9.10.7`.
+* Upgrades the `jjwt-jackson` module's Jackson dependency to `2.12.4`.
+* Updates Jackson usage (in `jjwt-jackson`) to use immutable classes instead of using `ObjectMapper` directly.
 
 ### 0.11.2
 

extensions/jackson/src/main/java/io/jsonwebtoken/jackson/io/JacksonDeserializer.java

@@ -19,6 +19,7 @@
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import com.fasterxml.jackson.databind.ObjectReader;
 import com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import io.jsonwebtoken.io.DeserializationException;
@@ -35,7 +36,7 @@
 public class JacksonDeserializer<T> implements Deserializer<T> {
 
     private final Class<T> returnType;
-    private final ObjectMapper objectMapper;
+    private final ObjectReader objectReader;
 
     @SuppressWarnings("unused") //used via reflection by RuntimeClasspathDeserializerLocator
     public JacksonDeserializer() {
@@ -68,14 +69,7 @@ public JacksonDeserializer() {
      * @param claimTypeMap The claim name-to-class map used to deserialize claims into the given type
      */
     public JacksonDeserializer(Map<String, Class> claimTypeMap) {
-        // DO NOT reuse JacksonSerializer.DEFAULT_OBJECT_MAPPER as this could result in sharing the custom deserializer
-        // between instances
-        this(new ObjectMapper());
-        Assert.notNull(claimTypeMap, "Claim type map cannot be null.");
-        // register a new Deserializer
-        SimpleModule module = new SimpleModule();
-        module.addDeserializer(Object.class, new MappedTypeDeserializer(Collections.unmodifiableMap(claimTypeMap)));
-        objectMapper.registerModule(module);
+        this(objectMapperWithMappedTypes(claimTypeMap));
     }
 
     @SuppressWarnings({"unchecked", "WeakerAccess", "unused"}) // for end-users providing a custom ObjectMapper
@@ -86,7 +80,7 @@ public JacksonDeserializer(ObjectMapper objectMapper) {
     private JacksonDeserializer(ObjectMapper objectMapper, Class<T> returnType) {
         Assert.notNull(objectMapper, "ObjectMapper cannot be null.");
         Assert.notNull(returnType, "Return type cannot be null.");
-        this.objectMapper = objectMapper;
+        this.objectReader = objectMapper.reader();
         this.returnType = returnType;
     }
 
@@ -101,7 +95,19 @@ public T deserialize(byte[] bytes) throws DeserializationException {
     }
 
     protected T readValue(byte[] bytes) throws IOException {
-        return objectMapper.readValue(bytes, returnType);
+        return objectReader.readValue(bytes, returnType);
+    }
+
+    private static ObjectMapper objectMapperWithMappedTypes(Map<String, Class> claimTypeMap) {
+        // DO NOT reuse JacksonSerializer.DEFAULT_OBJECT_MAPPER as this could result in sharing the custom deserializer
+        // between instances
+        Assert.notNull(claimTypeMap, "Claim type map cannot be null.");
+        ObjectMapper objectMapper = new ObjectMapper();
+        // register a new Deserializer
+        SimpleModule module = new SimpleModule();
+        module.addDeserializer(Object.class, new MappedTypeDeserializer(Collections.unmodifiableMap(claimTypeMap)));
+        objectMapper.registerModule(module);
+        return objectMapper;
     }
 
     /**
@@ -122,7 +128,7 @@ public Object deserialize(JsonParser parser, DeserializationContext context) thr
             // check if the current claim key is mapped, if so traverse it's value
             String name = parser.currentName();
             if (claimTypeMap != null && name != null && claimTypeMap.containsKey(name)) {
-                Class type = claimTypeMap.get(name);
+                Class<?> type = claimTypeMap.get(name);
                 return parser.readValueAsTree().traverse(parser.getCodec()).readValueAs(type);
             }
             // otherwise default to super

extensions/jackson/src/main/java/io/jsonwebtoken/jackson/io/JacksonSerializer.java

@@ -17,6 +17,7 @@
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectWriter;
 import io.jsonwebtoken.io.SerializationException;
 import io.jsonwebtoken.io.Serializer;
 import io.jsonwebtoken.lang.Assert;
@@ -28,7 +29,7 @@ public class JacksonSerializer<T> implements Serializer<T> {
 
     static final ObjectMapper DEFAULT_OBJECT_MAPPER = new ObjectMapper();
 
-    private final ObjectMapper objectMapper;
+    private final ObjectWriter objectWriter;
 
     @SuppressWarnings("unused") //used via reflection by RuntimeClasspathDeserializerLocator
     public JacksonSerializer() {
@@ -38,7 +39,7 @@ public JacksonSerializer() {
     @SuppressWarnings("WeakerAccess") //intended for end-users to use when providing a custom ObjectMapper
     public JacksonSerializer(ObjectMapper objectMapper) {
         Assert.notNull(objectMapper, "ObjectMapper cannot be null.");
-        this.objectMapper = objectMapper;
+        this.objectWriter = objectMapper.writer();
     }
 
     @Override
@@ -54,6 +55,6 @@ public byte[] serialize(T t) throws SerializationException {
 
     @SuppressWarnings("WeakerAccess") //for testing
     protected byte[] writeValueAsBytes(T t) throws JsonProcessingException {
-        return this.objectMapper.writeValueAsBytes(t);
+        return this.objectWriter.writeValueAsBytes(t);
     }
 }

extensions/jackson/src/test/groovy/io/jsonwebtoken/jackson/io/JacksonDeserializerTest.groovy

@@ -38,14 +38,14 @@ class JacksonDeserializerTest {
     @Test
     void testDefaultConstructor() {
         def deserializer = new JacksonDeserializer()
-        assertNotNull deserializer.objectMapper
+        assertNotNull deserializer.objectReader
     }
 
     @Test
     void testObjectMapperConstructor() {
         def customOM = new ObjectMapper()
         def deserializer = new JacksonDeserializer(customOM)
-        assertSame customOM, deserializer.objectMapper
+        assertSame customOM.getDeserializationConfig(), deserializer.objectReader.config
     }
 
     @Test(expected = IllegalArgumentException)

extensions/jackson/src/test/groovy/io/jsonwebtoken/jackson/io/JacksonSerializerTest.groovy

@@ -37,14 +37,14 @@ class JacksonSerializerTest {
     @Test
     void testDefaultConstructor() {
         def serializer = new JacksonSerializer()
-        assertNotNull serializer.objectMapper
+        assertNotNull serializer.objectWriter
     }
 
     @Test
     void testObjectMapperConstructor() {
         def customOM = new ObjectMapper()
         def serializer = new JacksonSerializer<>(customOM)
-        assertSame customOM, serializer.objectMapper
+        assertSame customOM.getSerializationConfig(), serializer.objectWriter.config
     }
 
     @Test(expected = IllegalArgumentException)

pom.xml

@@ -74,7 +74,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <buildNumber>${user.name}-${maven.build.timestamp}</buildNumber>
 
-        <jackson.version>2.9.10.7</jackson.version>
+        <jackson.version>2.12.4</jackson.version>
         <orgjson.version>20180130</orgjson.version>
         <gson.version>2.8.5</gson.version>