Add 1-based Month[De]serializer enabled with JavaTimeFeature.ONE_BASED_MONTHS option

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/JavaTimeFeature.java

@@ -29,7 +29,9 @@ public enum JavaTimeFeature implements JacksonFeature
      * stringified numbers are always accepted as timestamps regardless of
      * this feature.
      */
-    ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS(false)
+    ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS(false),
+
+    ONE_BASED_MONTHS(false)
     ;
 
   /**

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/JavaTimeModule.java

@@ -18,6 +18,7 @@
 
 import java.time.*;
 
+import com.fasterxml.jackson.core.json.PackageVersion;
 import com.fasterxml.jackson.core.util.JacksonFeatureSet;
 
 import com.fasterxml.jackson.databind.*;
@@ -142,6 +143,11 @@ public void setupModule(SetupContext context) {
         desers.addDeserializer(ZoneOffset.class, JSR310StringParsableDeserializer.ZONE_OFFSET);
 
         context.addDeserializers(desers);
+
+        boolean oneBasedMonth = _features.isEnabled(JavaTimeFeature.ONE_BASED_MONTHS);
+        context.addBeanDeserializerModifier(new JavaTimeDeserializerModifier(oneBasedMonth));
+        context.addBeanSerializerModifier(new JavaTimeSerializerModifier(oneBasedMonth));
+
         // 20-Nov-2023, tatu: [modules-java8#288]: someone may have directly
         //     added entries, need to add for backwards compatibility
         if (_deserializers != null) {

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/deser/JavaTimeDeserializerModifier.java

@@ -0,0 +1,32 @@
+package com.fasterxml.jackson.datatype.jsr310.deser;
+
+import java.time.Month;
+
+import com.fasterxml.jackson.databind.BeanDescription;
+import com.fasterxml.jackson.databind.DeserializationConfig;
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.JsonDeserializer;
+import com.fasterxml.jackson.databind.deser.BeanDeserializerModifier;
+
+/**
+ * @since 2.17
+ */
+public class JavaTimeDeserializerModifier extends BeanDeserializerModifier {
+    private final boolean _oneBaseMonths;
+
+    public JavaTimeDeserializerModifier() {
+        this(false);
+    }
+
+    public JavaTimeDeserializerModifier(boolean oneBaseMonths) {
+        _oneBaseMonths = oneBaseMonths;
+    }
+
+    @Override
+    public JsonDeserializer<?> modifyEnumDeserializer(DeserializationConfig config, JavaType type, BeanDescription beanDesc, JsonDeserializer<?> defaultDeserializer) {
+        if (type.hasRawClass(Month.class)) {
+            return new MonthDeserializer((JsonDeserializer<Enum>) defaultDeserializer, _oneBaseMonths);
+        }
+        return defaultDeserializer;
+    }
+}

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/deser/MonthDeserializer.java

@@ -0,0 +1,51 @@
+package com.fasterxml.jackson.datatype.jsr310.deser;
+
+import java.io.IOException;
+import java.time.Month;
+import java.util.regex.Pattern;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonDeserializer;
+import com.fasterxml.jackson.databind.deser.std.DelegatingDeserializer;
+import com.fasterxml.jackson.databind.exc.InvalidFormatException;
+
+/**
+ * @since 2.17
+ */
+public class MonthDeserializer extends DelegatingDeserializer {
+    private static final Pattern HAS_ONE_OR_TWO_DIGITS = Pattern.compile("^\\d{1,2}$");
+    private final boolean _enableOneBaseMonths;
+
+    public MonthDeserializer(JsonDeserializer<Enum> defaultDeserializer, boolean oneBaseMonths) {
+        super(defaultDeserializer);
+        _enableOneBaseMonths = oneBaseMonths;
+    }
+
+    @Override
+    public Object deserialize(JsonParser parser, DeserializationContext context) throws IOException {
+        JsonToken token = parser.currentToken();
+        Month zeroBaseMonth = (Month) getDelegatee().deserialize(parser, context);
+        if (!_enableOneBaseMonths || !_isNumericValue(parser.getText(), token)) {
+            return zeroBaseMonth;
+        }
+        if (zeroBaseMonth == Month.JANUARY) {
+            throw new InvalidFormatException(parser, "Month.JANUARY value not allowed for 1-based Month.", zeroBaseMonth, Month.class);
+        }
+        return zeroBaseMonth.minus(1);
+    }
+
+    private boolean _isNumericValue(String text, JsonToken token) {
+        return token == JsonToken.VALUE_NUMBER_INT || _isNumberAsString(text, token);
+    }
+
+    private boolean _isNumberAsString(String text, JsonToken token) {
+        return token == JsonToken.VALUE_STRING &&  HAS_ONE_OR_TWO_DIGITS.matcher(text).find();
+    }
+
+    @Override
+    protected JsonDeserializer<?> newDelegatingInstance(JsonDeserializer<?> newDelegatee) {
+        return new MonthDeserializer((JsonDeserializer<Enum>) newDelegatee, _enableOneBaseMonths);
+    }
+}

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/ser/JavaTimeSerializerModifier.java

@@ -0,0 +1,33 @@
+package com.fasterxml.jackson.datatype.jsr310.ser;
+
+import java.time.Month;
+
+import com.fasterxml.jackson.databind.BeanDescription;
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.SerializationConfig;
+import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;
+
+/**
+ * @since 2.17
+ */
+public class JavaTimeSerializerModifier extends BeanSerializerModifier {
+    private final boolean _oneBaseMonths;
+
+    public JavaTimeSerializerModifier() {
+        this(false);
+    }
+
+    public JavaTimeSerializerModifier(boolean oneBaseMonths) {
+        _oneBaseMonths = oneBaseMonths;
+    }
+
+    @Override
+    public JsonSerializer<?> modifyEnumSerializer(SerializationConfig config, JavaType valueType, BeanDescription beanDesc, JsonSerializer<?> serializer) {
+        if (valueType.hasRawClass(Month.class)) {
+            return new MonthSerializer((JsonSerializer<Enum>) serializer, _oneBaseMonths);
+        }
+        return serializer;
+    }
+
+}

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/ser/MonthSerializer.java

@@ -0,0 +1,36 @@
+package com.fasterxml.jackson.datatype.jsr310.ser;
+
+import java.io.IOException;
+import java.time.Month;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.SerializerProvider;
+
+/**
+ * @since 2.17
+ */
+public class MonthSerializer extends JsonSerializer<Enum<Month>> {
+    private final boolean _enableOneBaseMonths;
+    private final JsonSerializer<Enum> _defaultSerializer;
+
+    public MonthSerializer(JsonSerializer<Enum> defaultSerializer, boolean oneBaseMonths) {
+        _defaultSerializer = defaultSerializer;
+        _enableOneBaseMonths = oneBaseMonths;
+    }
+
+    @Override
+    public void serialize(Enum<Month> value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
+        if(_enableOneBaseMonths
+            /*
+                && we write the enum ordinal (int) value,
+                via WRITE_ENUMS_USING_INDEX or other similar construct
+            */
+        ) {
+            gen.writeNumber(value.ordinal() + 1);
+            return;
+        }
+        _defaultSerializer.serialize(value, gen, serializers);
+    }
+
+}