Add jackson behavior for methods

Added classes to make gson treat methods as jackson does.
Remove unneeded "forGetter" parameter from constructors.
Fixed sonar issue with too long "if" test.
Corrected comment about annotation names.
Adjusted error message.
Removed unused constant.
Removed trailing spaces.

Change-Id: I3a4fc92193737a0dc89f1218e70f093aedbdb152
Issue-ID: POLICY-1428
Signed-off-by: Jim Hahn <jrh3@att.com>

1 files changed, 202 insertions, 0 deletions

diff --git a/gson/src/main/java/org/onap/policy/common/gson/JacksonMethodAdapterFactory.java b/gson/src/main/java/org/onap/policy/common/gson/JacksonMethodAdapterFactory.java
new file mode 100644
index 00000000..1c3039f7
--- /dev/null
+++ b/gson/src/main/java/org/onap/policy/common/gson/JacksonMethodAdapterFactory.java
@@ -0,0 +1,202 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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=========================================================
+ */
+
+package org.onap.policy.common.gson;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+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.JsonWriter;
+import java.io.IOException;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import org.onap.policy.common.gson.internal.AnyGetterSerializer;
+import org.onap.policy.common.gson.internal.AnySetterDeserializer;
+import org.onap.policy.common.gson.internal.ClassWalker;
+import org.onap.policy.common.gson.internal.Deserializer;
+import org.onap.policy.common.gson.internal.MethodDeserializer;
+import org.onap.policy.common.gson.internal.MethodSerializer;
+import org.onap.policy.common.gson.internal.Serializer;
+
+/**
+ * Factory that serializes/deserializes class methods following the normal behavior of
+ * jackson. Supports the following annotations:
+ * <ul>
+ * <li>GsonJsonIgnore</li>
+ * <li>GsonJsonProperty</li>
+ * <li>GsonJsonAnyGetter</li>
+ * <li>GsonJsonAnySetter</li>
+ * </ul>
+ */
+public class JacksonMethodAdapterFactory implements TypeAdapterFactory {
+
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+        Class<? super T> clazz = type.getRawType();
+
+        if (!JacksonExclusionStrategy.isManaged(clazz)) {
+            return null;
+        }
+
+        ClassWalker data = new ClassWalker();
+        data.walkClassHierarchy(clazz);
+
+        if (data.getInProps(Method.class).isEmpty() && data.getOutProps(Method.class).isEmpty()) {
+            if (data.getAnyGetter() == null && data.getAnySetter() == null) {
+                // no methods to serialize
+                return null;
+            }
+        }
+
+        return new JacksonMethodAdapter<>(gson, data, gson.getDelegateAdapter(this, type));
+    }
+
+    /**
+     * Adapter for a single class.
+     *
+     * @param <T> type of class on which the adapter works
+     */
+    private static class JacksonMethodAdapter<T> extends TypeAdapter<T> {
+
+        /**
+         * Used to create an object of the given class.
+         */
+        private final TypeAdapter<T> delegate;
+
+        /**
+         * Used to serialize/deserialize a JsonElement.
+         */
+        private final TypeAdapter<JsonElement> elementAdapter;
+
+        /**
+         * Serializers for each item within the object.
+         */
+        private final Serializer[] serializers;
+
+        /**
+         * Deserializers for each item within the object.
+         */
+        private final Deserializer[] deserializers;
+
+        /**
+         * Constructs the object.
+         *
+         * @param gson the associated gson object
+         * @param data data used to configure the adapter
+         * @param delegate default constructor for the type
+         */
+        public JacksonMethodAdapter(Gson gson, ClassWalker data, TypeAdapter<T> delegate) {
+            this.delegate = delegate;
+
+            this.elementAdapter = gson.getAdapter(JsonElement.class);
+
+            Set<String> unliftedProps = new HashSet<>();
+            unliftedProps.addAll(data.getInNotIgnored());
+            unliftedProps.addAll(data.getOutNotIgnored());
+
+            // create serializers
+            this.serializers = makeSerializers(gson, data, unliftedProps).toArray(new Serializer[0]);
+
+            // create deserializers
+            this.deserializers = makeDeserializers(gson, data, unliftedProps).toArray(new Deserializer[0]);
+        }
+
+        /**
+         * Creates a complete list of serializers.
+         *
+         * @param gson the associated gson object
+         * @param data data used to configure the serializers
+         * @param unliftedProps properties that should not be lowered by "any-getters"
+         * @return a list of all serializers
+         */
+        private List<Serializer> makeSerializers(Gson gson, ClassWalker data, Set<String> unliftedProps) {
+            List<Serializer> ser = new ArrayList<Serializer>();
+
+            if (data.getAnyGetter() != null) {
+                ser.add(new AnyGetterSerializer(gson, unliftedProps, data.getAnyGetter()));
+            }
+
+            data.getOutProps(Method.class).forEach(method -> ser.add(new MethodSerializer(gson, method)));
+
+            return ser;
+        }
+
+        /**
+         * Creates a complete list of deserializers.
+         *
+         * @param gson the associated gson object
+         * @param data data used to configure the deserializers
+         * @param unliftedProps properties that should not be lifted by "any-setters"
+         * @return a list of all deserializers
+         */
+        private List<Deserializer> makeDeserializers(Gson gson, ClassWalker data, Set<String> unliftedProps) {
+            List<Deserializer> deser = new ArrayList<Deserializer>();
+
+            if (data.getAnySetter() != null) {
+                deser.add(new AnySetterDeserializer(gson, unliftedProps, data.getAnySetter()));
+            }
+
+            data.getInProps(Method.class).forEach(method -> deser.add(new MethodDeserializer(gson, method)));
+
+            return deser;
+        }
+
+        @Override
+        public void write(JsonWriter out, T value) throws IOException {
+            JsonElement tree = delegate.toJsonTree(value);
+
+            if (tree.isJsonObject()) {
+                JsonObject jsonObj = tree.getAsJsonObject();
+
+                // serialize each item from the value into the target tree
+                for (Serializer serializer : serializers) {
+                    serializer.addToTree(value, jsonObj);
+                }
+            }
+
+            elementAdapter.write(out, tree);
+        }
+
+        @Override
+        public T read(JsonReader in) throws IOException {
+            JsonElement tree = elementAdapter.read(in);
+
+            T object = delegate.fromJsonTree(tree);
+
+            if (tree.isJsonObject()) {
+                JsonObject jsonObj = tree.getAsJsonObject();
+
+                // deserialize each item from the tree into the target object
+                for (Deserializer dser : deserializers) {
+                    dser.getFromTree(jsonObj, object);
+                }
+            }
+
+            return object;
+        }
+    }
+}