Added an easier way to serialize simple objects using gson since this…

… is wideley used in the platform and core library.

src/main/java/org/hobbit/core/rabbit/GsonUtils.java

@@ -0,0 +1,59 @@
+package org.hobbit.core.rabbit;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.gson.Gson;
+
+/**
+ * A class that offers simple utility methods that hide some steps that are
+ * necessary to transform java objects into JSON containing byte arrays and vice
+ * versa.
+ * 
+ * @author Michael Röder ([email protected])
+ *
+ */
+public class GsonUtils {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(GsonUtils.class);
+
+    /**
+     * Serialize a Java object as JSON using the given {@link Gson} instance and the
+     * {@link RabbitMQUtils} class.
+     * 
+     * @param <T>    The class of the given object
+     * @param gson   The Gson instance used for the serialization as JSON
+     * @param object The object that should be serialized
+     * @return The serialized object as JSON in a byte representation or null if the
+     *         given object was null
+     */
+    public static <T> byte[] serializeObjectWithGson(Gson gson, T object) {
+        if (object != null) {
+            return RabbitMQUtils.writeString(gson.toJson(object));
+        }
+        return null;
+    }
+
+    /**
+     * Deserialize a Java data object that was received as JSON with a command.
+     * First, the given byte array will be transformed into a String using the
+     * {@link RabbitMQUtils} class, before it will be deserialized using the
+     * controller's {@link #gson} object.
+     * 
+     * @param <T>   The class that the data object should have.
+     * @param data  The byte array that has been received.
+     * @param clazz The class that the data object should have.
+     * @return The deserialized object or null if an error occurred
+     */
+    public static <T> T deserializeObjectWithGson(Gson gson, byte[] data, Class<? extends T> clazz) {
+        if (data != null) {
+            String dataString = RabbitMQUtils.readString(data);
+            try {
+                return gson.fromJson(dataString, clazz);
+            } catch (Exception e) {
+                LOGGER.error("Error while parsing JSON data. Returning null.");
+            }
+        }
+        return null;
+    }
+}

src/test/java/org/hobbit/core/rabbit/GsonUtilsTest.java

@@ -0,0 +1,39 @@
+package org.hobbit.core.rabbit;
+
+import org.hobbit.core.data.ErrorData;
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.google.gson.Gson;
+
+public class GsonUtilsTest {
+
+    @Test
+    public void testErrorData() {
+        ErrorData original = new ErrorData();
+        original.setErrorType("http://example.org/generalError");
+        original.setContainerId("123");
+
+        Gson gson = new Gson();
+        ErrorData received;
+
+        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
+                ErrorData.class);
+        Assert.assertEquals(original, received);
+
+        original.setLabel("Example label");
+        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
+                ErrorData.class);
+        Assert.assertEquals(original, received);
+
+        original.setDescription("Some description");
+        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
+                ErrorData.class);
+        Assert.assertEquals(original, received);
+
+        original.setDetails("A lot of details....");
+        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
+                ErrorData.class);
+        Assert.assertEquals(original, received);
+    }
+}