Java Web Start 和 Websockets 的 NoClassDefFoundError

Question

当我运行使用 "Run As -> Java Applet" 时，我的小程序在 Eclipse 中工作，但是当我尝试使用 JNLP 文件启动它时，我得到一个 NoClassDefFoundError。我正在尝试在我的应用程序中使用 javax.websocket-api，它使用 tyrus 实现。

Java代码：

import javax.websocket.DeploymentException;
import org.glassfish.tyrus.server.Server;

public class MyApplet extends Applet {
    Server server = new Server("localhost", 8025, "/root/", MyApplet.class);
    try {
        server.start();
    }
    catch (DeploymentException e) {
        e.printStackTrace();
    }
}

错误信息：

java.lang.RuntimeException: java.lang.NoClassDefFoundError: javax/websocket/DeploymentException
    at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter.instantiateApplet(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoClassDefFoundError: javax/websocket/DeploymentException
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    at java.lang.Class.getConstructor0(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)
    at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access0(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: javax.websocket.DeploymentException
    at sun.plugin2.applet.Plugin2ClassLoader.run(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.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)
    ... 24 more

Jnlp 文件：

<%@ page contentType="application/x-java-jnlp-file"%>
<?xml version="1.0" encoding="UTF-8"?>
<jnlp spec="1.5" codebase="http://localhost:7001/root">
    <information>
        <title>title</title>
        <vendor>vendor</vendor>
    </information>
    <security>
        <all-permissions/>
    </security>
    <resources>
        <java version="1.7*"/>
        <jar href="my_applet.jar" main="true"/>
        <jar href="tyrus-websocket-core-1.1.jar"/>
        <jar href="activation-1.1.jar"/>
        <jar href="tyrus-container-grizzly-1.2.1.jar"/>
        <jar href="tyrus-core-1.1.jar"/>
        <jar href="tyrus-server-1.1.jar"/>
        <jar href="tyrus-spi-1.2.1.jar"/>
        <jar href="grizzly-framework-2.3.3.jar"/>
        <jar href="grizzly-http-2.3.3.jar"/>
        <jar href="grizzly-http-server-2.3.3.jar"/>
        <jar href="grizzly-rcm-2.3.3.jar"/>
        <jar href="javaee-api-7.0.jar"/>
        <jar href="javax.mail-1.5.0.jar"/>
        <jar href="jnlp-api-7.0.jar"/>
        <jar href="javax.websocket-api-1.0.jar"/>
    </resources>
    <applet-desc main-class="myPackage.MyApplet" name="name" width="100" height="10">
</applet-desc>

jnlp 文件中给出的 jars 与在 eclipse 中指定的 Java Build Path 完全相同。 jar 文件部署在服务器上，我可以使用我的网络浏览器访问它们。

我的想法是它与 websockets-api 有关，它无法在运行时加载 tyrus 实现，但我不知道如何修复它。

Answer 1

原来错误是由我的 MANIFEST.MF 文件中的 Trusted-Library 属性引起的。因此，如果有人遇到类似问题，请检查您的清单文件是否不包含任何错误并且与您的 jnlp 文件一致。

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