[BAEL-6750] - Jackson Polymorphic Deserialization and SubTypes registration using Reflection API (#14503)

* [BAEL-6750] - Jackson Polymorphic Deserialization and SubTypes registration using Reflection API

* Renamed test files

---------

Co-authored-by: ovidiu-mihai98 <57233636+ovidiu-mihai98@users.noreply.github.com>

jackson-modules/jackson-polymorphic-deserialization/pom.xml

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>jackson-polymorphic-deserialization</artifactId>
+    <name>jackson-polymorphic-deserialization</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>jackson-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+            <version>${jackson-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.reflections</groupId>
+            <artifactId>reflections</artifactId>
+            <version>${reflections.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>jackson-polymorphic-deserialization</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <jackson-core.version>2.15.2</jackson-core.version>
+        <reflections.version>0.9.11</reflections.version>
+    </properties>
+
+</project>

jackson-modules/jackson-polymorphic-deserialization/src/main/java/com/baeldung/jackson/polymorphic/deserialization/reflection/Vehicle.java

@@ -0,0 +1,47 @@
+package com.baeldung.jackson.polymorphic.deserialization.reflection;
+
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "type", visible = true)
+public class Vehicle {
+
+    public String type;
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    @VehicleSubType("ELECTRIC_VEHICLE")
+    public static class ElectricVehicle extends Vehicle {
+
+        String autonomy;
+        String chargingTime;
+
+        public String getAutonomy() {
+            return autonomy;
+        }
+
+        public void setAutonomy(String autonomy) {
+            this.autonomy = autonomy;
+        }
+
+        public String getChargingTime() {
+            return chargingTime;
+        }
+
+        public void setChargingTime(String chargingTime) {
+            this.chargingTime = chargingTime;
+        }
+    }
+
+    @VehicleSubType("FUEL_VEHICLE")
+    public static class FuelVehicle extends Vehicle {
+
+        String fuelType;
+        String transmissionType;
+    }
+}

jackson-modules/jackson-polymorphic-deserialization/src/main/java/com/baeldung/jackson/polymorphic/deserialization/reflection/VehicleSubType.java

@@ -0,0 +1,13 @@
+package com.baeldung.jackson.polymorphic.deserialization.reflection;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface VehicleSubType {
+
+    String value();
+}

jackson-modules/jackson-polymorphic-deserialization/src/main/java/com/baeldung/jackson/polymorphic/deserialization/typeHandlingAnnotations/Vehicle.java

@@ -0,0 +1,66 @@
+package com.baeldung.jackson.polymorphic.deserialization.typeHandlingAnnotations;
+
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "type", visible = true)
+@JsonSubTypes({
+    @JsonSubTypes.Type(value = Vehicle.ElectricVehicle.class, name = "ELECTRIC_VEHICLE"),
+    @JsonSubTypes.Type(value = Vehicle.FuelVehicle.class, name = "FUEL_VEHICLE")
+})
+public class Vehicle {
+
+    public String type;
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public static class ElectricVehicle extends Vehicle {
+
+        String autonomy;
+        String chargingTime;
+
+        public String getAutonomy() {
+            return autonomy;
+        }
+
+        public void setAutonomy(String autonomy) {
+            this.autonomy = autonomy;
+        }
+
+        public String getChargingTime() {
+            return chargingTime;
+        }
+
+        public void setChargingTime(String chargingTime) {
+            this.chargingTime = chargingTime;
+        }
+    }
+
+    public static class FuelVehicle extends Vehicle {
+
+        String fuelType;
+        String transmissionType;
+
+        public String getFuelType() {
+            return fuelType;
+        }
+
+        public void setFuelType(String fuelType) {
+            this.fuelType = fuelType;
+        }
+
+        public String getTransmissionType() {
+            return transmissionType;
+        }
+
+        public void setTransmissionType(String transmissionType) {
+            this.transmissionType = transmissionType;
+        }
+    }
+}

jackson-modules/jackson-polymorphic-deserialization/src/test/java/com/baeldung/jackson/polymorphic/deserialization/reflection/ReflectionUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.jackson.polymorphic.deserialization.reflection;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+import org.reflections.Reflections;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.jsontype.NamedType;
+
+public class ReflectionUnitTest {
+
+    @Test
+    public void whenDeserializingPolymorphic_thenCorrect() throws JsonProcessingException {
+        String json = "{\"type\":\"ELECTRIC_VEHICLE\",\"autonomy\":\"500\",\"chargingTime\":\"200\"}";
+        ObjectMapper objectMapper = getCustomObjectMapper();
+
+        Vehicle vehicle = objectMapper.readValue(json, Vehicle.class);
+
+        assertEquals(Vehicle.ElectricVehicle.class, vehicle.getClass());
+    }
+
+    private ObjectMapper getCustomObjectMapper() {
+
+        ObjectMapper objectMapper = new ObjectMapper();
+
+        Reflections reflections = new Reflections("com.baeldung.jackson.polymorphic.deserialization.reflection");
+        Set<Class<?>> subtypes = reflections.getTypesAnnotatedWith(VehicleSubType.class);
+
+        for (Class<?> subType : subtypes) {
+            VehicleSubType annotation = subType.getAnnotation(VehicleSubType.class);
+            if (annotation != null) {
+                String typeName = annotation.value();
+                objectMapper.registerSubtypes(new NamedType(subType, typeName));
+            }
+        }
+
+        return objectMapper;
+    }
+}

jackson-modules/jackson-polymorphic-deserialization/src/test/java/com/baeldung/jackson/polymorphic/deserialization/typeHandlingAnnotations/TypeHandlingAnnotationsUnitTest.java

@@ -0,0 +1,20 @@
+package com.baeldung.jackson.polymorphic.deserialization.typeHandlingAnnotations;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class TypeHandlingAnnotationsUnitTest {
+
+    @Test
+    public void whenDeserializingPolymorphic_thenCorrect() throws JsonProcessingException {
+        String json = "{\"type\":\"ELECTRIC_VEHICLE\",\"autonomy\":\"500\",\"chargingTime\":\"200\"}";
+
+        Vehicle vehicle = new ObjectMapper().readerFor(Vehicle.class).readValue(json);
+
+        assertEquals(Vehicle.ElectricVehicle.class, vehicle.getClass());
+    }
+}

jackson-modules/pom.xml

@@ -22,6 +22,7 @@
         <module>jackson-custom-conversions</module>
         <module>jackson-exceptions</module>
         <module>jackson-jr</module>
+        <module>jackson-polymorphic-deserialization</module>
     </modules>
 
     <dependencies>