1 files changed, 76 insertions, 0 deletions
diff --git a/gson/src/main/java/org/onap/policy/common/gson/StringTypeAdapter.java b/gson/src/main/java/org/onap/policy/common/gson/StringTypeAdapter.java
new file mode 100644
index 00000000..22481697
--- /dev/null
+++ b/gson/src/main/java/org/onap/policy/common/gson/StringTypeAdapter.java
@@ -0,0 +1,76 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2021 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.JsonParseException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.util.function.Function;
+
+/**
+ * GSON Type Adapter for fields that are encoded as Strings.
+ */
+public class StringTypeAdapter<T> extends TypeAdapter<T> {
+    private final String exMessage;
+    private final Function<String, T> deserializer;
+    private final Function<T, String> serializer;
+
+    /**
+     * Constructs an adapter.
+     *
+     * @param type type of value, used in exception messages
+     * @param deserializer function used to deserialize a String into a value
+     * @param serializer function used to serialize a value into a String
+     */
+    public StringTypeAdapter(String type, Function<String, T> deserializer, Function<T, String> serializer) {
+        this.exMessage = "invalid " + type;
+        this.deserializer = deserializer;
+        this.serializer = serializer;
+    }
+
+    @Override
+    public T read(JsonReader in) throws IOException {
+        try {
+            if (in.peek() == JsonToken.NULL) {
+                in.nextNull();
+                return null;
+            } else {
+                return deserializer.apply(in.nextString());
+            }
+
+        } catch (RuntimeException e) {
+            throw new JsonParseException(exMessage, e);
+        }
+    }
+
+    @Override
+    public void write(JsonWriter out, T value) throws IOException {
+        if (value == null) {
+            out.nullValue();
+        } else {
+            String text = serializer.apply(value);
+            out.value(text);
+        }
+    }
+}