Add ObjetToJsonConverter interface implementation to convert an Object or PDX to JSON using Apache Geode's o.a.g.pdx.JSONFormatter class.

This converter extends (is backed by) the JacksonObjectToJsonConverter implementation to fallback on Jackson's ObjectMapper if the Object to convert is not a o.a.g.pdx.PdxInstance.

Resolves gh-67.

spring-geode/src/main/java/org/springframework/geode/data/json/converter/support/JSONFormatterPdxToJsonConverter.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package org.springframework.geode.data.json.converter.support;
+
+import java.util.Optional;
+
+import org.apache.geode.pdx.JSONFormatter;
+import org.apache.geode.pdx.PdxInstance;
+
+import org.springframework.geode.data.json.converter.ObjectToJsonConverter;
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
+
+/**
+ * An {@link ObjectToJsonConverter} implementation using the Apache Geode {@link JSONFormatter} to convert
+ * from a {@link PdxInstance} to a {@literal JSON} {@link String}.
+ *
+ * @author John Blum
+ * @see org.apache.geode.pdx.JSONFormatter
+ * @see org.apache.geode.pdx.PdxInstance
+ * @see org.springframework.geode.data.json.converter.ObjectToJsonConverter
+ * @see org.springframework.geode.data.json.converter.support.JacksonObjectToJsonConverter
+ * @since 1.3.0
+ */
+public class JSONFormatterPdxToJsonConverter extends JacksonObjectToJsonConverter {
+
+	/**
+	 * @inheritDoc
+	 */
+	@Nullable @Override
+	public final String convert(@Nullable Object source) {
+
+		return Optional.ofNullable(source)
+			.filter(PdxInstance.class::isInstance)
+			.map(PdxInstance.class::cast)
+			.map(this::convertPdxToJson)
+			.orElseGet(() -> convertObjectToJson(source));
+	}
+
+	/**
+	 * Converts the given {@link Object} to JSON.
+	 *
+	 * @param source {@link Object} to convert to JSON.
+	 * @return the JSON generated from the given {@link Object}.
+	 * @see JacksonObjectToJsonConverter#convert(Object)
+	 */
+	protected @Nullable String convertObjectToJson(Object source) {
+		return super.convert(source);
+	}
+
+	/**
+	 * Converts the given {@link PdxInstance PDX} to JSON.
+	 *
+	 * @param pdxInstance {@link PdxInstance} to convert to JSON; must not be {@literal null}.
+	 * @return JSON generated from the given {@link PdxInstance}.
+	 * @see org.apache.geode.pdx.JSONFormatter#toJSON(PdxInstance)
+	 * @see org.apache.geode.pdx.PdxInstance
+	 */
+	protected @NonNull String convertPdxToJson(@NonNull PdxInstance pdxInstance) {
+		return JSONFormatter.toJSON(pdxInstance);
+	}
+}

spring-geode/src/test/java/org/springframework/geode/data/json/converter/support/JSONFormatterPdxToJsonConverterUnitTests.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package org.springframework.geode.data.json.converter.support;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+
+import org.junit.Test;
+
+import org.apache.geode.pdx.PdxInstance;
+
+/**
+ * Unit Tests for {@link JSONFormatterPdxToJsonConverter}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.apache.geode.pdx.PdxInstance
+ * @see org.springframework.geode.data.json.converter.support.JSONFormatterPdxToJsonConverter
+ * @since 1.3.0
+ */
+public class JSONFormatterPdxToJsonConverterUnitTests {
+
+	@Test
+	public void convertsObjectToJson() {
+
+		String json = "{ \"name\": \"Jason Doe\" }";
+
+		Object object = new Object();
+
+		JSONFormatterPdxToJsonConverter converter = spy(new JSONFormatterPdxToJsonConverter());
+
+		doReturn(json).when(converter).convertObjectToJson(eq(object));
+
+		assertThat(converter.convert(object)).isEqualTo(json);
+
+		verify(converter, times(1)).convertObjectToJson(eq(object));
+		verify(converter, never()).convertPdxToJson(any());
+	}
+
+	@Test
+	public void convertsPdxInstanceToJson() {
+
+		String json = "{ \"name\": \"Jon Doe\" }";
+
+		PdxInstance mockPdxInstance = mock(PdxInstance.class);
+
+		JSONFormatterPdxToJsonConverter converter = spy(new JSONFormatterPdxToJsonConverter());
+
+		doReturn(json).when(converter).convertPdxToJson(eq(mockPdxInstance));
+
+		assertThat(converter.convertPdxToJson(mockPdxInstance)).isEqualTo(json);
+
+		verify(converter, times(1)).convertPdxToJson(eq(mockPdxInstance));
+		verify(converter, never()).convertObjectToJson(any());
+		verifyNoInteractions(mockPdxInstance);
+	}
+}