FOR
DUMMIES
Applets
an introduction
An applet is a small application of Java running in the contents of a
browser. The applet has to obey to security restrictions imposed on it
while running on a client machine. This means that an applet does not
have privilegies like reading files from local client machine in which
it is currently running. In the latest version of Java 2 this can be overriden
using signed applets. A signed applet asks the user if it is granted more
access to the local drive.
The Java virtual machine that is used by the browser determines which JDK is supported. Be sure to always use the latest browser available. However if you must build applets working for all browsers (Netscape and Internet Explorer) you must use JDK 1.0.2. The main problem with using this version is the lack of good IDEs for developing in this JDK. JBuilder from Inprise is an excellent IDE for both applets and applications. Visual J++ 6 sucks hard and long.
FAQ
Q:
Can an applet access my local drive an read secret information?
A: No. An applet extend tha Java class Applet which means that it does
not allow the applet to do so.
Q:
How do I attach an applet to a HTML file?
A: Create a zip file and cab file. There are some obstacles to overcome
due to the always present browser issue, look in the table below to find
out more.
| Netscape 3.02 | Internet Explorer 3.02 | NS4.5 | IE4.01 |
| Use a zip file. But do not compress the *.class files. | Make a cab file and use <param name="cabbase" value="mycabfile.cab"> in the applets inparamters | Use *.jar or *.zip. | Use *.zip or *.cab |