ros.tools

Class MessageUnpacker<T>

java.lang.Object

ros.tools.MessageUnpacker<T>

public class MessageUnpacker<T>
extends Object

This is a helper class that may be used for taking a JSON message returned from Ros bridge, and unpacking the actual ros message inside it into a Java bean object. (A Java bean is a Java object that has a default constructor and getter and has either public data members or getter and setter methods for the data members using standard Java naming conventions.)

To use this class, type the generic to the Java Bean class to which the message will be unpacked and provide the constructor the class of it as well. For example:

MessageUnpacker<Twist> unpacker = new MessageUnpacker<Twist>(Twist.class);. Then provide the unpackRosMessage(com.fasterxml.jackson.databind.JsonNode) method the JsonNode provided to a RosListenDelegate to unpack the "msg" field into the Java Bean. This will also work with Java Beans with generics. For example, you can do MessageUnpacker<PrimitiveMsg<String>> unpacker = new MessageUnpacker<PrimitiveMsg<String>>(PrimitiveMsg.class);.

Author:

James MacGlashan.

Field Summary

Fields

Modifier and Type	Field and Description
protected Class<?>	javaClass
protected com.fasterxml.jackson.databind.ObjectMapper	mapper

Constructor Summary

Constructors

Constructor and Description
MessageUnpacker(Class<?> javaClass) Constructor.

Method Summary

Modifier and Type	Method and Description
T	unpackRosMessage(com.fasterxml.jackson.databind.JsonNode rosBridgeMessage) Unpacks a ros message into the appropriate Java bean from the JSON message returned by ros bridge.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

mapper

protected com.fasterxml.jackson.databind.ObjectMapper mapper

javaClass

protected Class<?> javaClass

Constructor Detail

MessageUnpacker

public MessageUnpacker(Class<?> javaClass)

Constructor.

Parameters:

javaClass - a Class specifying the class of the Java bean into which a ros message will be unpacked.

Method Detail

unpackRosMessage

public T unpackRosMessage(com.fasterxml.jackson.databind.JsonNode rosBridgeMessage)

Unpacks a ros message into the appropriate Java bean from the JSON message returned by ros bridge. Note that the Ros bridge JSON message contains header information and the actual ROS message is stored in the 'msg' field in the JSON message. Therefore, this method should be provided the JsonNode that is given to a RosListenDelegate RosListenDelegate.receive(com.fasterxml.jackson.databind.JsonNode, String) method. If the provided JsonNode argument of this method does not have a "msg" field, then it will attempt to unpack from the whole JSON node.

Parameters:

rosBridgeMessage - the JsonNode from RosBridge.

Returns:

the unpacked Java Bean of the ROS message.