Move PojoCloudEventData in core

core/src/main/java/io/cloudevents/core/data/PojoCloudEventData.java

@@ -0,0 +1,74 @@
+package io.cloudevents.core.data;
+
+import io.cloudevents.CloudEventData;
+import io.cloudevents.rw.CloudEventRWException;
+
+import java.util.Objects;
+
+public class PojoCloudEventData<T> implements CloudEventData {
+
+    /**
+     * Interface defining a conversion from T to byte array. This is similar to {@link java.util.function.Function}
+     * but it allows checked exceptions.
+     *
+     * @param <T> the source type of the conversion
+     */
+    @FunctionalInterface
+    public interface ToBytes<T> {
+        byte[] convert(T data) throws Exception;
+    }
+
+    private final T value;
+    private byte[] memoizedValue;
+    private final ToBytes<T> mapper;
+
+    private PojoCloudEventData(T value, ToBytes<T> mapper) {
+        this(value, null, mapper);
+    }
+
+    private PojoCloudEventData(T value, byte[] memoizedValue, ToBytes<T> mapper) {
+        Objects.requireNonNull(value);
+        if (memoizedValue == null && mapper == null) {
+            throw new NullPointerException("You must provide the serialized data value or a mapper");
+        }
+        this.value = value;
+        this.memoizedValue = memoizedValue;
+        this.mapper = mapper;
+    }
+
+    public T getValue() {
+        return value;
+    }
+
+    @Override
+    public byte[] toBytes() {
+        if (this.memoizedValue == null) {
+            try {
+                this.memoizedValue = mapper.convert(this.value);
+            } catch (Exception e) {
+                throw CloudEventRWException.newDataConversion(e, value.getClass().toString(), "byte[]");
+            }
+        }
+        return this.memoizedValue;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PojoCloudEventData<?> that = (PojoCloudEventData<?>) o;
+        return Objects.equals(getValue(), that.getValue());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getValue());
+    }
+
+    /**
+     * Wrap the provided data in a {@link PojoCloudEventData} serializable by the provided mapper.
+     */
+    public static <T> PojoCloudEventData<T> wrap(T data, ToBytes<T> mapper) {
+        return new PojoCloudEventData<>(data, mapper);
+    }
+}

core/src/test/java/io/cloudevents/core/data/PojoCloudEventDataTest.java

@@ -0,0 +1,36 @@
+package io.cloudevents.core.data;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class PojoCloudEventDataTest {
+
+    @Test
+    void testWrapAndMemoization() {
+        PojoCloudEventData<Integer> data = PojoCloudEventData.wrap(10, i -> i.toString().getBytes());
+
+        assertThat(data.getValue())
+            .isEqualTo(10);
+
+        byte[] firstConversion = data.toBytes();
+
+        assertThat(firstConversion)
+            .isEqualTo("10".getBytes());
+
+        assertThat(data.toBytes())
+            .isSameAs(firstConversion);
+    }
+
+    @Test
+    void testAlreadySerializedValue() {
+        byte[] serialized = "10".getBytes();
+        PojoCloudEventData<Integer> data = PojoCloudEventData.wrap(10, v -> serialized);
+
+        assertThat(data.getValue())
+            .isEqualTo(10);
+
+        assertThat(data.toBytes())
+            .isSameAs(serialized);
+    }
+}

formats/json-jackson/src/main/java/io/cloudevents/jackson/PojoCloudEventDataMapper.java

@@ -5,8 +5,10 @@
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import io.cloudevents.CloudEventData;
+import io.cloudevents.core.data.PojoCloudEventData;
 import io.cloudevents.rw.CloudEventDataMapper;
 import io.cloudevents.rw.CloudEventRWException;
+
 import java.util.List;
 
 public class PojoCloudEventDataMapper<T> implements CloudEventDataMapper<PojoCloudEventData<T>> {
@@ -30,7 +32,7 @@ public PojoCloudEventData<T> map(CloudEventData data) throws CloudEventRWExcepti
             } catch (Exception e) {
                 throw CloudEventRWException.newDataConversion(e, JsonNode.class.toString(), target.getTypeName());
             }
-            return new PojoCloudEventData<>(mapper, value);
+            return PojoCloudEventData.wrap(value, mapper::writeValueAsBytes);
         }
 
         // Worst case, deserialize from bytes
@@ -41,11 +43,12 @@ public PojoCloudEventData<T> map(CloudEventData data) throws CloudEventRWExcepti
         } catch (Exception e) {
             throw CloudEventRWException.newDataConversion(e, byte[].class.toString(), target.getTypeName());
         }
-        return new PojoCloudEventData<>(mapper, value, bytes);
+        return PojoCloudEventData.wrap(value, v -> bytes);
     }
 
     /**
-     * Creates a {@link PojoCloudEventDataMapper} mapping {@link CloudEventData} into {@link PojoCloudEventData}&lt;T&gt;.
+     * Creates a {@link PojoCloudEventDataMapper} mapping {@link CloudEventData} into {@link PojoCloudEventData}&lt;T&gt;
+     * using a Jackson {@link ObjectMapper}.
      *
      * <p>
      * When working with generic types (e.g. {@link List}&lt;{@link String}&gt;),
@@ -62,7 +65,8 @@ public static <T> PojoCloudEventDataMapper<T> from(ObjectMapper mapper, Class<T>
     }
 
     /**
-     * Creates a {@link PojoCloudEventDataMapper} mapping {@link CloudEventData} into {@link PojoCloudEventData}&lt;T&gt;.
+     * Creates a {@link PojoCloudEventDataMapper} mapping {@link CloudEventData} into {@link PojoCloudEventData}&lt;T&gt;
+     * using a Jackson {@link ObjectMapper}.
      *
      * <p>
      * This overload is more suitable for mapping generic objects (e.g. {@link List}&lt;{@link String}&gt;),

formats/json-jackson/src/test/java/io/cloudevents/jackson/PojoCloudEventDataMapperTest.java

@@ -7,8 +7,8 @@
 import io.cloudevents.CloudEvent;
 import io.cloudevents.core.CloudEventUtils;
 import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.core.data.PojoCloudEventData;
 import io.cloudevents.core.test.Data;
-import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;