Developing Java Beans

Creating a JAR File

Let’s package up the simulator classes in a JAR file. This will allow us to distribute the entire package in one unit, as well as to test the Beans using BeanBox. The first step is to create a manifest file called Simulator.mf, naming each class and specifying whether or not they are Beans. Marking a class as a Bean is meant to indicate that it qualifies as an object that exposes events, methods, and properties, and that it is a useful object in its own right. The listener interfaces and the event objects are useful, but they provide no useful function by themselves. The TemperatureModifier isn’t marked as a Bean; it is the abstract base class for the Cooler and Boiler Beans, and so can never be instantiated by itself. The manifest file looks as follows:

Manifest-Version: 1.0

Name: BeansBook/Simulator/Boiler.class
Java-Bean: True

Name: BeansBook/Simulator/Cooler.class
Java-Bean: True

Name: BeansBook/Simulator/CoolingRequestListener.class
Java-Bean: False

Name: BeansBook/Simulator/HeatingRequestListener.class
Java-Bean: False

Name: BeansBook/Simulator/ServiceRequestEvent.class
Java-Bean: False

Name: BeansBook/Simulator/Temperature.class
Java-Bean: True

Name: BeansBook/Simulator/TemperatureModifier.class
Java-Bean: False

Name: BeansBook/Simulator/TemperaturePulseEvent.class
Java-Bean: False

Name: BeansBook/Simulator/TemperaturePulseListener.class
Java-Bean: False

Name: BeansBook/Simulator/Thermostat.class
Java-Bean: True

Note that only the Boiler, Cooler, Temperature ...