java - WebStart 可以使用 DownloadService 动态加载 jar 吗？

Question

我尝试使用以下代码动态加载 jar 资源。

    DownloadService ds; 

    try { 
        ds = (DownloadService)ServiceManager.lookup("javax.jnlp.DownloadService"); 

        // determine if a particular resource is cached
        URL url = 
                new URL("http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar"); 
        boolean cached = ds.isResourceCached(url, "1.0"); 
        // remove the resource from the cache 
        if (cached) { 
            ds.removeResource(url, "1.0"); 
        } 
        // reload the resource into the cache 
        DownloadServiceListener dsl = ds.getDefaultProgressWindow(); 
        ds.loadResource(url, "1.0", dsl); 
    } catch (Exception e) { 
        e.printStackTrace(); 
    } 

但是我收到如下错误。

    cache: Create from verifier: JarSigningData{hasOnlySignedEntries=true, hasSingleCodeSource=true, hasMissingSignedEntries=false}
    network: Cache: Enable a new CacheEntry: http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar
    network: CleanupThread used 1 us
    network: Downloaded http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar: C:\Users\Administrator\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\63\774e407f-457c5f64-1.0-
    cache: Adding MemoryCache entry: http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar
    network: Download Progress: jarsDone: 1
     2013-08-30 14:19:53,959     4881 [AWT-EventQueue-2] INFO  com.ktnet.pki.multibrowser.dialog.SelectCertificateDlg$10  -  MOBILE_PHONE  param BOKJIRO;KTNET;null;null;null
    security: blacklist: hasBeenModifiedSince 1377837583053 (we have 1377739208656)
    network: cache found [URL: http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar, 버전: null] prevalidated=false/0
    cache: MemoryCache replacing http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar (refcnt=2). Was: URL: http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar | C:\Users\Administrator\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\63\774e407f-457c5f64-1.0-.idx Now: URL: http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar | C:\Users\Administrator\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\63\774e407f-13638c52.idx
    cache: Reading Signers from 4389 http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar | C:\Users\Administrator\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\63\774e407f-13638c52.idx
    cache: Done readSigners(http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar)
    cache:  Read manifest for http://localhost:11090/MultiToolkitDemo/download/ubikey-1.0.2.5.jar: read=72 full=5090
    Exception in thread "AWT-EventQueue-2" java.lang.NullPointerException
        at sun.plugin2.applet.JNLP2ClassLoader.getAppInfo(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.isTrustedByTrustDecider(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.getTrustedCodeSources(Unknown Source)
        at com.sun.deploy.security.CPCallbackHandler$ParentCallback.strategy(Unknown Source)
        at com.sun.deploy.security.CPCallbackHandler$ParentCallback.openClassPathElement(Unknown Source)
        at com.sun.deploy.security.DeployURLClassPath$JarLoader.getJarFile(Unknown Source)
        at com.sun.deploy.security.DeployURLClassPath$JarLoader.access$1000(Unknown Source)
        at com.sun.deploy.security.DeployURLClassPath$JarLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.deploy.security.DeployURLClassPath$JarLoader.ensureOpen(Unknown Source)
        at com.sun.deploy.security.DeployURLClassPath$JarLoader.<init>(Unknown Source)
        at com.sun.deploy.security.DeployURLClassPath$3.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
        at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
        at com.sun.deploy.security.DeployURLClassPath.getResource(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Unknown Source)
        at sun.plugin2.applet.JNLP2ClassLoader.findClass(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at com.ktnet.pki.multibrowser.certificate.infovine.InfovineController.init(InfovineController.java:19)

我认为 AppInfo 丢失了。有没有办法动态插入AppInfo。

顺便说一句，像下面这样在 jnlp 中指定 jar 就可以了。

    <resources>
        <j2se version="1.6+" java-vm-args="-Dfile.encoding=UTF-8" />

        <jar href="ubikey-1.0.2.5.jar" />

    </resources>

Answer 1

Its possibly a bug in java7. Don't know that for sure.

The issue here is that the application won't launch unless we manually clear the cache everytime before clicking the JNLP link in webpage.

Possible solutions are

Try Java 6 or Java 7 u12.

看 where我发现了这个问题。