Hello world! as a Java Applet

We are interested now in focusing on those changes that have to be made to make HelloClient.java an applet.
In what follows, we assume that the applet runs in the appletviewer.
Modification are indicated in red.
In this example, I have created a package called examples.helloApplet.
To properly access the class files that we create and put into it, we set the CLASSPATH environment variable to the directory in which examples/helloApplet is rooted.
For example, if our packages our in $home/packages, then we set CLASSPATH to $home/packages.

The client

package examples.helloApplet

import java.applet.Applet;
import java.awt.Graphics;
import java.rmi.Naming;
import java.rmi.RemoteException;

public class HelloApplet extends Applet {

String message = "blank"; // the string constructed in the try statement
Hello obj = null;

            public void init() {
                try {                       // "//<hostname>/<objectname>"
                    obj = (Hello)Naming.lookup("//lysander.cs.ucsb.edu/HelloServer");
                    message = obj.sayHello();
                } catch (Exception e) {
                    System.out.println("HelloApplet exception: " + e.getMessage());
                    e.printStackTrace();
                }
            }

            public void paint(Graphics g) {
                g.drawString(message, 25, 50);
            }
        }

Here is the HTML code for the web page that references the Hello World applet:

    <HTML>
    <title>Hello World</title>
    <center> <h1>Hello World</h1> </center>

    The message from the HelloServer is:
    <p>
    <applet code="examples.helloApplet.HelloApplet.class"
            width=500 height=120>
    </applet>
    </HTML>

Since CLASSPATH is set, the applet's code attribute specifies the fully-qualified package name of the applet:

code="examples.helloApplet.HelloApplet.class"

Compile and Deploy Class Files

When you use the javac and rmic compilers, you must specify where the resulting class files should reside.

Compile the Java source files

$HOME/myclasses

$HOME/mysrc/examples/hello

CLASSPATH

While in the source directory where these files reside, execute:

javac -d $HOME/packages Hello.java HelloImpl.java HelloApplet.java

This command creates the directory examples/helloApplet (if it does not already exist) in the directory $HOME/packages.
The command then writes to that directory the files Hello.class, HelloImpl.class, and HelloApplet.class. These are the remote interface, the implementation, and the client respectively.

javac

Solaris javac manual page

Win32 javac manual page

Use `rmic` to generate skeletons and/or stubs

rmic

rmic examples.helloApplet.HelloImpl

Start the RMI registry, server, and client

Start the RMI registry
For example, on Solaris:
rmiregistry &
For example, on Windows 95 or Windows NT:
start rmiregistry
For more on the rmiregistry, please refer to the Solaris rmiregistry manual page or the Win32 rmiregistry manual page.
Start the server

For Solaris:

java examples.helloApplet.HelloImpl &

For Windows:

java examples.helloApplet.HelloImpl

Run the client
Once the registry and server are running, the client can be run as follows, from within the directory that contains the html file:
appletviewer HelloApplet.html
After running the client, you will see "Hello world!".

Hello world! as a Java Applet

The client

Compile and Deploy Class Files

Compile the Java source files

Use rmic to generate skeletons and/or stubs

Start the RMI registry, server, and client

Start the RMI registry

Start the server

Run the client

Use `rmic` to generate skeletons and/or stubs