how to write deserlizer java
package net.sghill.example; import net.sghill.example.User; import org.codehaus.jackson.JsonNode; import org.codehaus.jackson.JsonParser; import org.codehaus.jackson.ObjectCodec; import org.codehaus.jackson.map.DeserializationContext; import org.codehaus.jackson.map.JsonDeserializer; import java.io.IOException; public class UserDeserializer extends JsonDeserializer<User> { @Override public User deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException { ObjectCodec oc = jsonParser.getCodec(); JsonNode node = oc.readTree(jsonParser); return new User(null, node.get("username").getTextValue(), node.get("password").getTextValue()); } }