I was aware of it is good to use data handler in Java to transfer files. Anyone can point me a good example or tutorial which help me understand this class.
Also, the package belongs to javax.activation.DataHandler, what is activation mean? is it a special library?
The JavaDocs for the javax.activation package somewhat clarifies the use of "activation" in the name.
It refers to the JavaBeans Activation Framework:
With the JavaBeans Activation Framework standard extension, developers who use Java technology can take advantage of standard services to determine the type of an arbitrary piece of data, encapsulate access to it, discover the operations available on it, and to instantiate the appropriate bean to perform said operation(s). For example, if a browser obtained a JPEG image, this framework would enable the browser to identify that stream of data as an JPEG image, and from that type, the browser could locate and instantiate an object that could manipulate, or view that image.
