Moved ODataTypeParametrizedIJsonBackedObjectAdapter to it's own file.

Author: PrimosK

src/main/java/com/microsoft/graph/serializer/ODataTypeParametrizedIJsonBackedTypedAdapter.java

@@ -0,0 +1,63 @@
+package com.microsoft.graph.serializer;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.TypeAdapter;
+import com.google.gson.internal.Streams;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.microsoft.graph.logger.ILogger;
+
+import java.io.IOException;
+import java.util.Objects;
+import javax.annotation.Nonnull;
+
+/**
+ * This adapter is responsible for deserialization of IJsonBackedObjects where service
+ * returns one of several derived types of a base object, which is defined using the
+ * odata.type parameter. If odata.type parameter is not found, the Gson default
+ * (delegated) type adapter is used.
+ */
+class ODataTypeParametrizedIJsonBackedTypedAdapter extends TypeAdapter<IJsonBackedObject> {
+
+    private final FallbackTypeAdapterFactory fallbackTypeAdapterFactory;
+    private final Gson gson;
+    private final TypeAdapter<IJsonBackedObject> delegatedAdapter;
+    private final TypeToken<IJsonBackedObject> type;
+    private final DerivedClassIdentifier derivedClassIdentifier;
+
+    public ODataTypeParametrizedIJsonBackedTypedAdapter(FallbackTypeAdapterFactory fallbackTypeAdapterFactory, @Nonnull Gson gson,
+        @Nonnull TypeAdapter<IJsonBackedObject> delegatedAdapter, @Nonnull final TypeToken<IJsonBackedObject> type, @Nonnull final ILogger logger)
+    {
+        super();
+        this.fallbackTypeAdapterFactory = fallbackTypeAdapterFactory;
+        this.gson = Objects.requireNonNull(gson, "parameter gson cannot be null");
+        this.delegatedAdapter = Objects.requireNonNull(delegatedAdapter, "object delegated adapted cannot be null");
+        this.type = Objects.requireNonNull(type, "object type cannot be null");
+        this.derivedClassIdentifier = new DerivedClassIdentifier(logger);
+    }
+
+    @Override
+    public void write(JsonWriter out, IJsonBackedObject value)
+        throws IOException
+    {
+        this.delegatedAdapter.write(out, value);
+    }
+
+    @Override
+    public IJsonBackedObject read(JsonReader in) {
+        JsonElement jsonElement = Streams.parse(in);
+
+        if (jsonElement.isJsonObject()) {
+            final Class<?> derivedClass = derivedClassIdentifier.identify(jsonElement.getAsJsonObject(), type.getRawType());
+
+            if (derivedClass != null) {
+                final TypeAdapter<?> subTypeAdapter = gson.getDelegateAdapter(fallbackTypeAdapterFactory, TypeToken.get(derivedClass));
+                return (IJsonBackedObject) subTypeAdapter.fromJsonTree(jsonElement);
+            }
+        }
+
+        return delegatedAdapter.fromJsonTree(jsonElement);
+    }
+}