手动更新jar包中的class文件，报java.lang.ClassNotFoundException或java.lang.NoClassDefFoundError问题记录

Laugh-toy

已于 2022-09-02 14:18:20 修改

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分类专栏： JAVA基础文章标签： tomcat java

于 2022-09-02 14:17:32 首次发布

本文链接：https://blog.youkuaiyun.com/BeginToTiger/article/details/126660978

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博客讨论了在服务器部署时遇到的NoClassDefFoundError和ClassNotFoundException异常。问题源于类加载的不同阶段，NoClassDefFoundError在初始化阶段报错，而ClassNotFoundException在加载阶段找不到类。解决办法是确保在手动更新jar包时包含所有匿名内部类的class文件。这提醒开发者在更新jar时需仔细检查所有依赖和子类。

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1.问题描述

本地代码运行无问题，手动更新class文件到jar包，部署到服务器的tomcat上启动时无报错，但登录网站使用 对应功能 时，报 java.lang.ClassNotFoundException 或 java.lang.NoClassDefFoundError 异常。
java.lang.NoClassDefFoundError 异常堆栈：

SEVERE: Servlet.service() for servlet [WFMDownloadFOAServlet] in context with path [/oss] threw exception [Servlet execution threw an exception] with root cause
java.lang.NoClassDefFoundError: Could not initialize class com.ztesoft.zsmart.oss.prj.entel2.wfm.util.HttpsUtil
	at com.ztesoft.zsmart.oss.prj.entel2.wfm.servlet.CustDownloadFOAServlet.doGet(CustDownloadFOAServlet.java:75)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1115)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)

java.lang.ClassNotFoundException 异常堆栈：

SEVERE: Servlet.service() for servlet [WFMDownloadFOAServlet] in context with path [/oss] threw exception [Servlet execution threw an exception] with root cause
java.lang.ClassNotFoundException: com.ztesoft.zsmart.oss.prj.entel2.wfm.util.Https$1
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1892)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735)
	at com.ztesoft.zsmart.oss.prj.entel2.wfm.util.Https.<clinit>(Https.java:32)
	at com.ztesoft.zsmart.oss.prj.entel2.wfm.servlet.CustDownloadFOAServlet.doGet(CustDownloadFOAServlet.java:72)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1115)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)

2.原因分析

java.lang.NoClassDefFoundError:
Could not initialize class com.ztesoft.zsmart.oss.prj.entel2.wfm.util.HttpsUtil

java.lang.ClassNotFoundException: com.ztesoft.zsmart.oss.prj.entel2.wfm.util.Https$1

java.lang.NoClassDefFoundError与java.lang.ClassNotFoundException这两个报错看似相似，其实不同。NoClassDefFoundError异常是能找到HttpsUtil这个类，但是在初始化这个类的时候报错；而ClassNotFoundException异常就是普通的找不到这个类。这两个报错发生在类加载的不同阶段。
类加载过程分为加载、链接、初始化。ClassNotFoundException异常发生在加载的过程，在加载com.ztesoft.zsmart.oss.prj.entel2.wfm.util.Https$1这个类时，找不到对应的class文件，因此报错；而NoClassDefFoundError异常发生在类的初始化过程，能找到com.ztesoft.zsmart.oss.prj.entel2.wfm.util.HttpsUtil这个类，但是在初始化这个类的时候报错了。初始化类的时候会去加载这个类的父类，并执行静态代码块，因此要检查这个类引用的父类是否存在或静态代码块中有没有问题。