adding helper for serialization format of object mapper to be array

msgpack-jackson/README.md

@@ -83,3 +83,15 @@ Java
   // xs => [zero, 1, 2.0, null]
 ```
 
+### Serialization format
+
+By default, the serialization format is object, which means it includes the schema of the serialized entity (POJO).
+To serialize an entity without the schema, only as array, you can add the annotation `@JsonFormat(shape=JsonFormat.Shape.ARRAY)` to the entity definition.
+Also, it's possible to set the serialization format for the object mapper instance to be array by changing the annotation inspector of object mapper to `JsonArrayFormat`:
+
+```
+  ObjectMapper objectMapper = new ObjectMapper(new MessagePackFactory());
+  objectMapper.setAnnotationIntrospector(new JsonArrayFormat());
+```
+
+This format provides compatibility with msgpack-java 0.6.x serialization api.

msgpack-jackson/src/main/java/org/msgpack/jackson/dataformat/JsonArrayFormat.java

@@ -0,0 +1,33 @@
+package org.msgpack.jackson.dataformat;
+
+import com.fasterxml.jackson.annotation.JsonFormat;
+import com.fasterxml.jackson.databind.introspect.Annotated;
+import com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector;
+
+import static com.fasterxml.jackson.annotation.JsonFormat.Shape.ARRAY;
+
+/**
+ * Provides the ability of serializing POJOs without their schema.
+ * Similar to @JsonFormat annotation with JsonFormat.Shape.ARRAY, but in a programmatic
+ * way.
+ *
+ * This also provides same behavior as msgpack-java 0.6.x serialization api.
+ *
+ * @author marenzo
+ */
+public class JsonArrayFormat extends JacksonAnnotationIntrospector {
+
+  private final static JsonFormat.Value ARRAY_FORMAT = new JsonFormat.Value().withShape(ARRAY);
+
+  @Override
+  public JsonFormat.Value findFormat(Annotated ann)
+  {
+    // If the entity contains JsonFormat annotation, give it higher priority.
+    JsonFormat.Value precedenceFormat = super.findFormat(ann);
+    if (precedenceFormat != null) {
+      return precedenceFormat;
+    }
+
+    return ARRAY_FORMAT;
+  }
+}

msgpack-jackson/src/test/java/org/msgpack/jackson/dataformat/MessagePackDataformatForPojoTest.java

@@ -15,12 +15,18 @@
 //
 package org.msgpack.jackson.dataformat;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.Test;
 
 import java.io.IOException;
+import java.nio.charset.Charset;
 import java.util.Arrays;
 
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.CoreMatchers.containsString;
+
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
 public class MessagePackDataformatForPojoTest
@@ -99,4 +105,18 @@ public void testChangingPropertyNames()
         ChangingPropertyNamesPojo value = objectMapper.readValue(bytes, ChangingPropertyNamesPojo.class);
         assertEquals("komamitsu", value.getTheName());
     }
+
+    @Test
+    public void testSerializationWithoutSchema()
+            throws IOException
+    {
+        ObjectMapper objectMapper = new ObjectMapper(factory); // to not affect shared objectMapper state
+        UsingCustomConstructorPojo orig = new UsingCustomConstructorPojo("komamitsu", 55);
+        objectMapper.setAnnotationIntrospector(new JsonArrayFormat());
+        byte[] bytes = objectMapper.writeValueAsBytes(orig);
+        String scheme = new String(bytes, Charset.forName("UTF-8"));
+        assertThat(scheme, not(containsString("name")));
+        UsingCustomConstructorPojo value = objectMapper.readValue(bytes, UsingCustomConstructorPojo.class);
+        assertEquals("komamitsu", value.name);
+    }
 }