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Putting Applets into Web Pages

Two things are involved in the process of
putting applets onto web pages
◦ The .class files of the applet
◦ The html file of the page

Remember: any Java source file that compiles
correctly will produce a .class file.

Compiled .class files for Java source code
should be found:
◦ C:/UserName/workspace/NameOfProject/bin

It may also be found in
◦ C:/UserName/Android/workspace/NameOfProject/
bin

The HTML file should be created inside the
same folder as the .class files for the applet.
◦ This is to reduce complexity in defining the path to
the applet class in the HTML file.

You could start creating an HTML file in
Notepad by:
◦ Starting a new text file, and adding your code from
there
◦ When it comes time to save, remove the *.txt
extension, and add ‘.html’ to the end of the file
instead. (Ex: MyHtmlPage.html)
<html>
<applet code=“MyJavaApplet.class”
width=“500” height=“500”>
</applet>
</html>
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HTML is a markup language, using a system
of tags to define elements of a document.
<html> is a tag that denotes a start of an
html file, while </html> denotes the end.
Likewise, <applet> and </applet> are used
in the same way.

You’ll notice inside the first applet tag, there
are attributes assigned inside it (code, width,
height)
◦ ‘code’ is the directory where the HTML file would be
able to find the main .class entry point for the
applet.
◦ ‘width’ and ‘height’ define the size as it appears on
the web page.
◦ Note that the values assigned to these attributes
are defined in double quotes.

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If you have to change a line in the source
code of the Java files and recompile, you
should replace the .class file in the html
directory with the new one.
When running Java applets, the user must
have the Java Runtime Environment installed.
For security or other reasons, some systems
may not run Java content through web pages.

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With the newest version of Java, unsigned
applets are not allowed to run on any
machine.
This means that if we try running our applet
through an html page we created, the applet
will not run at all, because it is considered a
security risk.
Therefore, we’ll need to create an exception
for this.

Open the Java Control Panel
◦ On Windows start, search for “Configure Java”
◦ Java\jre7\bin\javacpl.exe


Go to the Security tab, and click the “Edit Site
List…” button.
In the blank space on the dialog, type in the file
or html location of the html file you want to run.
◦ Ex: http://math.uaa.alaska.edu/~android/
java/unit5/unit5applet

Click Add, then OK on both dialogs. You should
be able to run that applet now.

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