Question

Applet, JNLP, native library, UnsatisfiedLinkError

Asked by: KhaiPi

I am using Java 6 Update 16.

I have an applet from which I would like to access code in a DLL (natives-1.1.dll).  The applet is launched via JNLP and is a true applet that runs inside the browser.  I have put the DLL into a JAR (natives-1.1.jar) and signed the JAR and also signed the applet's JAR with the same certificate.  I have included a <nativelib> element in the JNLP.  However, when I try to load the library inside the applet I get an UnsatisfiedLinkError:

Validating http://localhost:8080/test/applet.jar , version null...
Validating http://localhost:8080/test/natives-1.1.jar , version null...
Exception in thread "thread MyApplet-2" java.lang.UnsatisfiedLinkError: no natives-1.1 in java.library.path
      at java.lang.ClassLoader.loadLibrary(Unknown Source)
      at java.lang.Runtime.loadLibrary0(Unknown Source)
      at java.lang.System.loadLibrary(Unknown Source)
      at MyApplet$1.run(MyApplet.java:39)
      at java.security.AccessController.doPrivileged(Native Method)
      at MyApplet.init(MyApplet.java:36)
      at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
      at java.lang.Thread.run(Unknown Source)

So as you can see, it's definitely downloading the JAR containing the DLL.

The code in the applet to load the library looks like this:

AccessController.doPrivileged(new PrivilegedAction() {
    public Object run() {
        try {
            System.loadLibrary("natives-1.1");
        } catch (Exception e) {
        }
        return null;
    }
});

and the relevant JNLP entry looks like this:

<resources os="Windows" arch="x86">
      <nativelib href="natives-1.1.jar" download="eager"/>
</resources>

I am only running on a Windows x86 machine at the moment so it should work and it's definitely being downloaded as above.

Can someone tell me why the DLL is not being found?

Thanks,

KP

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Asked On
2009-08-22 at 20:18:24ID24674231
Tags

Java

,

JNLP

,

applet

Topic

Java Programming Language

Participating Experts
1
Points
500
Comments
7

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Answers

 

by: objectsPosted on 2009-08-22 at 20:23:44ID: 25161236

jnlp is used for loading applications, not applets so my guess is the jnlp is not getting loaded.
How are you loading the applet?

 

by: objectsPosted on 2009-08-22 at 20:25:38ID: 25161241

and check your jar contains the correctly named dll

 

by: objectsPosted on 2009-08-22 at 20:28:16ID: 25161244

Ignore my first comment if you're using the latest plugin on the client

 

by: KhaiPiPosted on 2009-08-22 at 20:30:20ID: 25161248

Actually JNLP can be used to load applets.  You just have an <applet> tag in the HTML page which links to a JNLP file via a "jnlp_href" parameter.

And I've checked that the JAR contains the correctly named DLL.

 

by: objectsPosted on 2009-08-22 at 20:31:35ID: 25161250

whats the name of the dll in the jar

jar tvf natives-1.1.jar

 

by: KhaiPiPosted on 2009-08-22 at 21:23:43ID: 25161353

natives-1.1.dll

 

by: KhaiPiPosted on 2009-08-22 at 21:55:19ID: 31619305

Hi objects,

I have decided to give you the points even though the solution was a little different.  The problem was that the JAR containing the DLL was signed by a different cert than the applet's JAR.  Your suggestion was close as it was related to that JAR.

Thanks.

20120131-EE-VQP-002

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