提问人：Spidermaninja 提问时间：9/10/2013 最后编辑：NimanthaSpidermaninja 更新时间：11/15/2023 访问量：544
Java 小程序在 IDE 中有效，但在浏览器中无效
Java applet works in IDE, but not in browser
问：
因此，我创建了一个简单的游戏，不久前就可以运行了。但是，最近，当我尝试在任何浏览器中运行它时，它只会给我一个 NullPointerException。线程堆栈如下：
cache: Initialize resource manager: com.sun.deploy.cache.ResourceProviderImpl@18a270a
security: property package.access value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.
security: property package.access new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.definition value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.
security: property package.definition new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.access value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.access new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.definition value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.definition new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.access value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.access new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss,com.sun.browser,com.sun.glass,com.sun.javafx,com.sun.media.jfxmedia,com.sun.media.jfxmediaimpl,com.sun.openpisces,com.sun.prism,com.sun.scenario,com.sun.t2k,com.sun.webpane,com.sun.pisces,com.sun.webkit
security: property package.definition value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.definition new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss,com.sun.browser,com.sun.glass,com.sun.javafx,com.sun.media.jfxmedia,com.sun.media.jfxmediaimpl,com.sun.openpisces,com.sun.prism,com.sun.scenario,com.sun.t2k,com.sun.webpane,com.sun.pisces,com.sun.webkit
basic: Added progress listener: sun.plugin.util.ProgressMonitorAdapter@13b7c28
network: Cache entry not found [url: file:////files5.ad.lake.stark.k12.oh.us/shd/2015/15TROYERJONATHAN/Documents/Computer%20Science/Game/GUI.class, version: null]
network: Cache entry not found [url: file:////files5.ad.lake.stark.k12.oh.us/shd/2015/15TROYERJONATHAN/Documents/Computer%20Science/Game/, version: null]
security: Accessing keys and certificate in Mozilla user profile: null
network: Created version ID: 1.7.0.25
network: Created version ID: 1.7.0.25
security: SSV validation: running: 1.7.0_25, requested: null, range: null
network: Created version ID: 1.7.0.25
network: Created version ID: 1.7.0.25
security: continue with running version
network: Cache entry not found [url: file:////files5.ad.lake.stark.k12.oh.us/shd/2015/15TROYERJONATHAN/Documents/Computer%20Science/Game/ColorPanel.class, version: null]
basic: Applet loaded.
basic: Applet resized and added to parent container
basic: PERF: AppletExecutionRunnable - applet.init() BEGIN ; jvmLaunch dt 216867 us, pluginInit dt 217500 us, TotalTime: 434367 us
java.lang.NullPointerException
at GUI.init(GUI.java:70)
at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter.init(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
basic: Removed progress listener: sun.plugin.util.ProgressMonitorAdapter@13b7c28
security: Reset deny session certificate store
这是错误所在（至少据我所知）：
URL url=getCodeBase();
String u=url.toString();
当小程序在 JCreator 中运行时，它可以正常工作，但在任何浏览器或 Adobe Dreamweaver 中都不能。线程堆栈是什么意思？
答：
1赞
C.Champagne
9/18/2013
#1
我想这是你的小程序类的名称。（顺便说一句，如果您定义了它的包，那应该很好，但它对这个问题没有影响）GUI
从您传输的跟踪中的堆栈跟踪中，我还可以假设您在问题中输入的两行代码是第 69 行和第 70 行。
因此，我可以假设返回，以便下一行自动导致 （NPE）。从 Java 7 update 25 开始，当小程序从本地文件系统运行时，getCodeBase（） 返回 null。getCodeBase()nullNullPointerException
因此，您应该检查 getCodeBase（） 返回的值是否为 null，以便您的代码可能如下所示：
String u = "Some default value";
URL url=getCodeBase();
if(url != null) {
u=url.toString();
}
评论
0赞
Spidermaninja
9/23/2013
有什么方法可以规避这一点吗？我知道getDocumentBase（）也返回null，但是应该有某种方法可以访问我的文件。
0赞
C.Champagne
9/24/2013
@Spidermaninja这可能是另一个问题的对象！问题是我并不确切知道你需要什么。无论如何，您输入的用于访问网页的 URL 似乎类似于 file:////my_resource_path....which 是一个文件路径，可以被视为本地路径。您当然应该使用真正的 Web 服务器并使用 HTTP 地址访问它。
评论