运行JAR包时出现java.lang.NoClassDefFoundError: sun/reflect/Reflection异常求助
问题描述
使用Eclipse构建了配置好主类的JAR包,在Windows命令行执行以下命令时:
java -Xms512m -Xmx1024m -jar foo.jar config.ini
抛出如下异常:
Exception in thread "main" java.lang.NoClassDefFoundError: sun/reflect/Reflection at com.jidesoft.plaf.UIDefaultsLookup.getCallerClassLoader(Unknown Source) at com.jidesoft.plaf.UIDefaultsLookup.get(Unknown Source) at com.jidesoft.plaf.vsnet.VsnetWindowsUtils.initComponentDefaultsWithMenu(Unknown Source) at com.jidesoft.plaf.LookAndFeelFactory.installJideExtension(Unknown Source) at com.jidesoft.plaf.LookAndFeelFactory.installJideExtension(Unknown Source) at com.jidesoft.plaf.LookAndFeelFactory.installJideExtension(Unknown Source) at com.jidesoft.swing.JideButton.updateUI(Unknown Source) at java.desktop/javax.swing.AbstractButton.init(AbstractButton.java:2136) at java.desktop/javax.swing.JButton.<init>(JButton.java:131) at java.desktop/javax.swing.JButton.<init>(JButton.java:85) at com.jidesoft.swing.JideButton.<init>(Unknown Source) at com.jidesoft.swing.JideButton.<init>(Unknown Source) at ro.sync.ui.application.lb.<init>(Unknown Source) at ro.sync.exml.m.d.<init>(Unknown Source) at ro.sync.exml.m.d.dqe(Unknown Source) at ro.sync.exml.m.c.<init>(Unknown Source) at ro.sync.ecss.extensions.api.component.AuthorComponentFactory$2.<init>(Unknown Source) at ro.sync.ecss.extensions.api.component.AuthorComponentFactory.init(Unknown Source) at ro.sync.ecss.extensions.api.component.AuthorComponentFactory.init(Unknown Source) at ro.sync.ecss.samples.AuthorComponentSample.<init>(AuthorComponentSample.java:311) at ro.sync.ecss.samples.AuthorComponentSample.main(AuthorComponentSample.java:545) Caused by: java.lang.ClassNotFoundException: sun.reflect.Reflection at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:602) at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) ... 21 more
原因分析
sun.reflect.Reflection是Sun/Oracle JDK的内部API,从Java 9开始,模块化系统默认限制了对这类内部API的访问。当前使用的JIDE组件依赖该内部类,而运行环境是Java 9及以上版本,导致类加载失败。
解决方案
- 降级Java运行环境到Java 8:Java 8中
sun.reflect.Reflection属于公开可访问的类,直接使用Java 8执行JAR包即可解决异常。 - 添加JVM参数开放内部API访问(临时方案):如果必须使用Java 9+,在启动命令中添加
--add-exports参数,修改后的命令如下:
注意:该方案仅为临时 workaround,内部API可能在后续Java版本中被移除,不建议长期依赖。java -Xms512m -Xmx1024m --add-exports java.base/sun.reflect=ALL-UNNAMED -jar foo.jar config.ini - 升级JIDE组件版本:查找并使用支持Java 9及以上版本的JIDE库,替换项目中的旧依赖后重新打包JAR,从根源解决兼容性问题。
内容的提问来源于stack exchange,提问作者Mahesh M
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