1 files changed, 124 insertions, 0 deletions
diff --git a/champ-lib/champ-core/src/main/java/org/onap/aai/champcore/event/envelope/util/GsonUtil.java b/champ-lib/champ-core/src/main/java/org/onap/aai/champcore/event/envelope/util/GsonUtil.java
new file mode 100644
index 0000000..df64040
--- /dev/null
+++ b/champ-lib/champ-core/src/main/java/org/onap/aai/champcore/event/envelope/util/GsonUtil.java
@@ -0,0 +1,124 @@
+/**
+ * ============LICENSE_START==========================================
+ * org.onap.aai
+ * ===================================================================
+ * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
+ * Copyright © 2017 Amdocs
+ * ===================================================================
+ * 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
+ *
+ *        http://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.
+ * ============LICENSE_END============================================
+ * ECOMP is a trademark and service mark of AT&T Intellectual Property.
+ */
+package org.onap.aai.champcore.event.envelope.util;
+
+import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.Optional;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+
+public class GsonUtil {
+
+    /**
+     * All methods are static.
+     */
+    private GsonUtil() {
+        // Do not instantiate
+    }
+
+    /**
+     * Tell Gson how to handle Optional fields. This factory builds a Type Adapter for a class wrapped
+     * with Optional
+     *
+     */
+    public static class OptionalTypeAdapterFactory implements TypeAdapterFactory {
+        @SuppressWarnings({"unchecked", "rawtypes"})
+        @Override
+        public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+            Class<T> rawType = (Class<T>) type.getRawType();
+            if (rawType != Optional.class) {
+                return null;
+            }
+            final ParameterizedType parameterizedType = (ParameterizedType) type.getType();
+            final Type actualType = parameterizedType.getActualTypeArguments()[0];
+            return new OptionalTypeAdapter(gson.getAdapter(TypeToken.get(actualType)));
+        }
+    }
+
+    /**
+     * Implementation of the Optional Type Adapter
+     *
+     * @param <E>
+     */
+    public static class OptionalTypeAdapter<E> extends TypeAdapter<Optional<E>> {
+
+        private final TypeAdapter<E> adapter;
+
+        public static final TypeAdapterFactory FACTORY = new OptionalTypeAdapterFactory();
+
+        /**
+         * @param adapter
+         */
+        public OptionalTypeAdapter(TypeAdapter<E> adapter) {
+            this.adapter = adapter;
+        }
+
+        @Override
+        public void write(JsonWriter out, Optional<E> value) throws IOException {
+            if (value != null && value.isPresent()) { // NOSONAR
+                adapter.write(out, value.get());
+            } else {
+                boolean nullsAllowed = out.getSerializeNulls();
+                if (nullsAllowed) {
+                    out.setSerializeNulls(false);
+                }
+                out.nullValue();
+                if (nullsAllowed) {
+                    out.setSerializeNulls(true);
+                }
+            }
+        }
+
+        @Override
+        public Optional<E> read(JsonReader in) throws IOException {
+            final JsonToken peek = in.peek();
+            if (peek != JsonToken.NULL) {
+                return Optional.ofNullable(adapter.read(in));
+            }
+            return Optional.empty();
+        }
+
+    }
+
+    /**
+     * @return a new GsonBuilder with standard settings
+     */
+    public static GsonBuilder createGsonBuilder() {
+        return new GsonBuilder().disableHtmlEscaping().setPrettyPrinting()
+                .registerTypeAdapterFactory(OptionalTypeAdapter.FACTORY);
+    }
+
+    /**
+     * @return a new Gson instance
+     */
+    public static Gson createGson() {
+        return createGsonBuilder().create();
+    }
+}