Applet White Screen

kimechani..

in Integration and Hardware • 1 year ago

Hi,

I'm trying to upload an applet onto the web but I just get a white screen of the correct size. When I opened up the html I just got a white screen and I also uploaded it onto openprocessing http://www.openprocessing.org/sketch/57645 and had the same result.

I wasn't sure what to do with the data folder that has images and an excel sheet. I looked into it and wasn't sure if I had to sign it as well.

Any help would be greatly appreciated, thanks.

Replies(3)

PhiLho

Re: Applet White Screen

1 year ago

It is always useful to look at the Java console when running applets:

Exception in thread "Animation Thread" java.lang.ExceptionInInitializerError
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at org.apache.poi.hssf.record.RecordFactory.class$(RecordFactory.java:46)
    at org.apache.poi.hssf.record.RecordFactory.<clinit>(RecordFactory.java:44)
    at org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:205)
    at org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:153)
    at de.bezier.data.XlsReader.<init>(Unknown Source)
    at HCI.loadExcel(HCI.java:1827)
    at HCI.setup(HCI.java:162)
    at processing.core.PApplet.handleDraw(Unknown Source)
    at processing.core.PApplet.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.security.AccessControlException: access denied (java.util.PropertyPermission poi.deserialize.escher read)
    at java.security.AccessControlContext.checkPermission(Unknown Source)
    at java.security.AccessController.checkPermission(Unknown Source)
    at java.lang.SecurityManager.checkPermission(Unknown Source)
    at java.lang.SecurityManager.checkPropertyAccess(Unknown Source)
    at java.lang.System.getProperty(Unknown Source)
    at org.apache.poi.hssf.record.AbstractEscherHolderRecord.<clinit>(AbstractEscherHolderRecord.java:41)
    ... 12 more

Apparently, Apache POI doesn't like to read a file from a jar, or in an applet context or something.
Or perhaps it is using reflection to create the classes to access the data and this isn't allowed in a low authorization applet environment.
Perhaps you can sign the library jars as well, but IIRC Open Processing doesn't run signed applets (unless it has changed).
A simple workaround would be to export your Excel data to the CSV format. It is less convenient (needing some extra code) but it would avoid to load a complex library just to access the data...

kimechani..

Re: Applet White Screen

1 year ago

Sorry I'm really new to this and have no idea how to look at the Java console. But thanks for your help! I'll try to use a CSV format which will hopefully solve the problem.

PhiLho

Re: Applet White Screen

1 year ago

A little googling can reveal how to show the Java console: http://www.java.com/en/download/help/javaconsole.xml for example.

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