GWT -> Javascript -> Applet communication
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rana
Oct 19, 2010, 11:26:36 AM10/19/10
to Google Web Toolkit
I am running a java applet within GWT, and require 2 way
communication.
The applet exposes a public method to do something on the applet. No
problem here, I am able to call this method from my GWT class as
follows:
public static native String invokeOnApplet(String appletID) /*-{
var c = $wnd.document.getElementById(appletID).invokeOnApplet();
return c;
}-*/;
But implementing callback from the Applet is not working. However, I
am able to invoke a pure javascript function defined inside the html
HEAD tag.
My GWT entry class:
--------------------------------------------
public class MyClient implements EntryPoint {
public void onModuleLoad() {
exportCallbackFunction();
}
public static native void exportCallbackFunction() /*-{
$wnd.funcAppletToGWT = @MyClient::funcAppletToGWT(Ljava/lang/
String;Ljava/lang/String;);
}-*/;
public static void funcAppletToGWT(String funcType, String param) {
Window.alert("in funcAppletToGWT() : " + funcType + ", " + param);
}
}
--------------------------------------------
HTML code:
--------------------------------------------
<html>
<head>
<script LANGUAGE="JavaScript">
function funcOther(param1, param2) {
alert('in funcOther() : ' + param1 + ', ' + param2);
}
</script>
</head>
<body>
...
<button type="button"
onclick="funcAppletToGWT('FTYPEX','PARAM33')">test funcAppletToGWT</
button>
<applet name="..." id="..." codebase="..."
code="TestApplet.class" width="100%" height="100%"
archive="..." MAYSCRIPT>
<param name="JS_FUNC_NAME" value="funcAppletToJS" >
</applet>
...
</body>
</html>
--------------------------------------------
Applet code:
--------------------------------------------
import netscape.javascript.*;
public class TestApplet extends Applet {
...
public String invokeOnApplet() {
return "invoked on Applet";
}
public void actionPerformed(ActionEvent ae) {
JSObject win = (JSObject) JSObject.getWindow(this);
win.call(getParameter("JS_FUNC_NAME"), new Object[] {"FTYPEY",
"PARAM44"});
}
}
--------------------------------------------
On button click, funcAppletToGWT() is being correctly called. But when
I invoke the same from my applet, the applet throws the following
error:
[19/10 14:03:55 - AWT-EventQueue-2] ERROR:
[TestApplet.actionPerformed] failed to call javascript-function:
funcAppletToJS with params=[STANDARD_ORDER,20735]
reason: netscape.javascript.JSException: JavaScript error while
calling "funcAppletToJS"
netscape.javascript.JSException: JavaScript error while calling
"funcAppletToJS"
at
sun.plugin2.main.client.MessagePassingJSObject.newJSException(Unknown
Source)
at
sun.plugin2.main.client.MessagePassingJSObject.waitForReply(Unknown
Source)
at sun.plugin2.main.client.MessagePassingJSObject.call(Unknown
Source)
If I replace the exported method with a regular javascript function,
then the function gets invoked fine.
e.g. <param name="JS_FUNC_NAME" value="funcOther" >
Any pointer/help is appreciated.
regards,
Rana
communication.
The applet exposes a public method to do something on the applet. No
problem here, I am able to call this method from my GWT class as
follows:
public static native String invokeOnApplet(String appletID) /*-{
var c = $wnd.document.getElementById(appletID).invokeOnApplet();
return c;
}-*/;
But implementing callback from the Applet is not working. However, I
am able to invoke a pure javascript function defined inside the html
HEAD tag.
My GWT entry class:
--------------------------------------------
public class MyClient implements EntryPoint {
public void onModuleLoad() {
exportCallbackFunction();
}
public static native void exportCallbackFunction() /*-{
$wnd.funcAppletToGWT = @MyClient::funcAppletToGWT(Ljava/lang/
String;Ljava/lang/String;);
}-*/;
public static void funcAppletToGWT(String funcType, String param) {
Window.alert("in funcAppletToGWT() : " + funcType + ", " + param);
}
}
--------------------------------------------
HTML code:
--------------------------------------------
<html>
<head>
<script LANGUAGE="JavaScript">
function funcOther(param1, param2) {
alert('in funcOther() : ' + param1 + ', ' + param2);
}
</script>
</head>
<body>
...
<button type="button"
onclick="funcAppletToGWT('FTYPEX','PARAM33')">test funcAppletToGWT</
button>
<applet name="..." id="..." codebase="..."
code="TestApplet.class" width="100%" height="100%"
archive="..." MAYSCRIPT>
<param name="JS_FUNC_NAME" value="funcAppletToJS" >
</applet>
...
</body>
</html>
--------------------------------------------
Applet code:
--------------------------------------------
import netscape.javascript.*;
public class TestApplet extends Applet {
...
public String invokeOnApplet() {
return "invoked on Applet";
}
public void actionPerformed(ActionEvent ae) {
JSObject win = (JSObject) JSObject.getWindow(this);
win.call(getParameter("JS_FUNC_NAME"), new Object[] {"FTYPEY",
"PARAM44"});
}
}
--------------------------------------------
On button click, funcAppletToGWT() is being correctly called. But when
I invoke the same from my applet, the applet throws the following
error:
[19/10 14:03:55 - AWT-EventQueue-2] ERROR:
[TestApplet.actionPerformed] failed to call javascript-function:
funcAppletToJS with params=[STANDARD_ORDER,20735]
reason: netscape.javascript.JSException: JavaScript error while
calling "funcAppletToJS"
netscape.javascript.JSException: JavaScript error while calling
"funcAppletToJS"
at
sun.plugin2.main.client.MessagePassingJSObject.newJSException(Unknown
Source)
at
sun.plugin2.main.client.MessagePassingJSObject.waitForReply(Unknown
Source)
at sun.plugin2.main.client.MessagePassingJSObject.call(Unknown
Source)
If I replace the exported method with a regular javascript function,
then the function gets invoked fine.
e.g. <param name="JS_FUNC_NAME" value="funcOther" >
Any pointer/help is appreciated.
regards,
Rana
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