向Eclipse插件添加Jar包至类路径失败，报NoClassDefFoundError

问题描述 #

我正尝试将org.json.simple Jar包添加至一个Eclipse插件中。查阅资料后，我尝试了右键项目→Build Path→配置→库→添加外部Jar的操作，也试过使用“添加Jar”并将Jar包放在项目根目录或lib文件夹下，但均未生效。无论是在Eclipse中启动应用，还是导出后启动，都持续出现NoClassDefFoundError错误（启动画面不显示为另一独立问题）。我目前的临时解决方案是将该Jar包的源码制作成插件并添加到我的feature中。

错误日志 #

!SESSION 2024-09-01 13:58:16.796 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.8.0_421
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments:  -product tcmagic.ui.product -clearPersistedState
Command-line arguments:  -product tcmagic.ui.product -data C:\Users\Danny\Downloads\EclipseRcpPluginDev\Neon3\workspace11/../runtime-tcmagic.product -dev file:C:/Users/Danny/Downloads/EclipseRcpPluginDev/Neon3/workspace11/.metadata/.plugins/org.eclipse.pde.core/tcmagic.product/dev.properties -os win32 -ws win32 -arch x86_64 -consoleLog -clearPersistedState -data @noDefault

!ENTRY org.eclipse.osgi 4 0 2024-09-01 13:58:20.829
!MESSAGE Application error
!STACK 1
org.eclipse.e4.core.di.InjectionException: org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NoClassDefFoundError: org/json/simple/parser/ParseException)
    at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:65)
    at org.eclipse.e4.core.internal.di.InjectorImpl.invokeUsingClass(InjectorImpl.java:282)
    at org.eclipse.e4.core.internal.di.InjectorImpl.invoke(InjectorImpl.java:259)
    at org.eclipse.e4.core.contexts.ContextInjectionFactory.invoke(ContextInjectionFactory.java:107)
    at org.eclipse.e4.ui.internal.workbench.swt.E4Application.lambda$0(E4Application.java:238)
    at java.util.Optional.ifPresent(Unknown Source)
    at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:234)
    at org.eclipse.e4.ui.internal.workbench.swt.E4Application.start(E4Application.java:148)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1519)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1492)
Caused by: org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NoClassDefFoundError: org/json/simple/parser/ParseException)
    at org.eclipse.swt.SWT.error(SWT.java:4533)
    at org.eclipse.swt.SWT.error(SWT.java:4448)
    at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:185)
    at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4211)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3827)
    at tcmagic.ui.Splash.prompt(Splash.java:119)
    at tcmagic.ui.LifeCycle.postContextCreate(LifeCycle.java:25)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:55)
    ... 20 more
Caused by: java.lang.NoClassDefFoundError: org/json/simple/parser/ParseException
    at tcmagic.db.mtgjson.Mtgjson.getSetListFile(Mtgjson.java:102)
    at tcmagic.db.mtgjson.Mtgjson.getSetLists(Mtgjson.java:110)
    at tcmagic.db.Database.createCards(Database.java:41)
    at tcmagic.ui.Splash.run(Splash.java:51)
    at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
    at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:182)
    ... 29 more
Caused by: java.lang.ClassNotFoundException: org.json.simple.parser.ParseException cannot be found by tcmagic.db_1.0.0.qualifier
    at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:461)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:372)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:364)
    at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 35 more
An error has occurred. See the log file
C:\Users\Danny\Downloads\EclipseRcpPluginDev\Neon3\workspace11\.metadata\.plugins\org.eclipse.pde.core\tcmagic.product\1725217097207.log.

解决方案 #

方法1：将Jar包嵌入到插件中（推荐） #

• 在插件项目内创建lib文件夹，把org.json.simple.jar复制进去
• 右键插件项目 → PDE Tools → Open Manifest Editor（打开MANIFEST.MF文件）
• 切换到Runtime标签页，在Classpath区域点击Add，选择lib/org.json.simple.jar添加
• 切换到Build标签页，在Binary Build区域勾选lib文件夹及其中的Jar包，确保构建时包含该文件
• 保存MANIFEST.MF，重新构建插件项目后测试

方法2：将Jar包转换为独立OSGi插件（适合多项目复用） #

• 打开File → New → Project → Plug-in from existing JAR archives
• 选择org.json.simple.jar，按照向导完成OSGi插件的创建
• 在目标插件的MANIFEST.MF的Dependencies标签页，添加这个新插件的依赖
• 更新feature和product配置，确保包含该新插件

配置验证要点 #

• 检查MANIFEST.MF的Bundle-ClassPath是否包含lib/org.json.simple.jar（方法1）
• 确认插件依赖列表已正确添加对应的OSGi插件（方法2）
• 重启PDE应用，验证NoClassDefFoundError是否消失

内容的提问来源于stack exchange，提问作者Daniel Vaughn