1,ServletInvokerApplet base class for the calling applet.

• By David Tayouri
• November 17, 2000

  /** Extend this applet to have the ability of
      servlet method invocation.
      The servlet to be invoked usually will
      extend InvocableServlet
*/
public abstract class ServletInvokerApplet
    extends java.applet.Applet
{
    protected URL servletUrl;

    //=========================================
    /** Opens an output connection to the
        servlet and passes the method name
        and its parameters (as a vector).
        The return value is read from the input
        stream and returned as an object.
     */
    protected Object invokeServletMethod(
        String methodName,
        Vector params)
    {
        Object returnValue = null;
        try {
            // Connect
            URLConnection conn = 
                servletUrl.openConnection();
            conn.setDoOutput(true);
            conn.setUseCaches(false);
            conn.setRequestProperty(
                "Content-Type",
                "application/octet-stream");

            // Open output stream, send method
            // name and its params
            // and close the stream
            ObjectOutputStream out =
                new ObjectOutputStream(
                    conn.getOutputStream());
            out.writeObject(methodName);
            out.writeObject(params);
            out.flush();
            out.close();

            // Open input stream, read the
            // data and close the stream
            ObjectInputStream in =
                new ObjectInputStream(
                   conn.getInputStream());
            returnValue = in.readObject();
            in.close();
        } catch (Exception e) {
            System.out.println(e);
        }
        return returnValue;
    }
}