Java and XML

Reading an XML Configuration File

To allow our XML-RPC classes to use our configuration file, we must create a helper class that parses the information and then makes it available to the server and clients. Although we could build this behavior into methods within the XML-RPC classes (similar to how the getHandlers( ) method was used in our LightweightServer class), using a separate class allows this class to be shared by both the clients and server, reducing duplication of code. We have already determined the information that needs to be obtained and can begin by writing a skeleton class with accessor methods for that data. The actual contents of the member variables we use will be populated by the parsing behavior we write in a moment.

Getting the Configuration Information

We could add code directly to the com.oreilly.xml.LightweightXmlRpcServer class to parse a configuration file; we could then add similar code to our XML-RPC clients that performed the same task. However, this results in a lot of duplicate code. Instead, another com.oreilly.xml utility class is introduced here: XmlRpcConfiguration. The beginnings of this class are shown in Example 11.3; a constructor takes in either a filename or an InputStream to read XML configuration data from. Simple accessor methods are also provided to access the configuration data once it has been loaded. By isolating the input and output of the class from specific XML constructs, we can change the parsing mechanism (which we look at ...