Java Reference
In-Depth Information
*/
void
void
loadApplet
(
String appletName
,
int
int
h
) {
// appletName = ... extract from the HTML CODE= somehow ...;
// width = ditto
// height = ditto
try
int
w
,
int
try
{
// get a Class object for the Applet subclass
ac
=
Class
.
forName
(
appletName
);
// Construct an instance (as if using no-argument constructor)
ai
= (
Applet
)
ac
.
newInstance
();
}
catch
catch
(
ClassNotFoundException e
) {
showStatus
(
"Applet subclass "
+
appletName
+
" did not load"
);
return
return
;
}
catch
catch
(
Exception e
){
showStatus
(
"Applet "
+
appletName
+
" did not instantiate"
);
return
return
;
}
ai
.
setSize
(
w
,
h
);
}
public
public
void
void
showStatus
(
String s
) {
aa
.
getAppletContext
().
showStatus
(
s
);
}
}
For
Applet
methods to work, two additional classes must be defined:
AppletStub
and
Ap-
pletContext
. The
AppletStub
is the tie-in between the applet and the browser, and the
Ap-
pletContext
is a set of methods used by the applet. In a real browser, they are probably im-
plemented separately, but I have combined them into one class (see
Example 23-25
)
. Note
that the scope of applets that will work without throwing exceptions is rather limited, be-
cause so many of the methods here are, at present, dummied out. This
AppletViewer
is not a
full replacement for the standard
AppletViewer
; it has been tested only with a basic Hello
World applet, and it is simply provided as a starting point for those who want to fill in the
gaps and make a full-blown applet viewer program or some other reflection-based tool that
works in a similar fashion.
Example 23-25. AppletAdapter.java, partial AppletStub, and AppletContext
public
public class
class
AppletAdapter
AppletAdapter
extends
extends
Panel
implements
implements
AppletStub
,
AppletContext
{
private
private static
long
serialVersionUID
=
1L
;
/** The status window at the bottom */
Label status
=
null
static final
final
long
null
;
