问题

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sDefFoundError: com/mysql/jdbc/Driver
d-color:#272822;">

我正在尝试运行简单的代码与MySQL连接。我正在使用Eclipse和Tomcat。 我已经在Libraries中添加了mysql-connector-java-8.0.1.9.jar： Libraries--&gt;mysql--&gt;mysql-connector-java-8.0.1.9.jar 我已经花了几个小时来添加和移除mysql-connector-java-8.0.1.9.jar到构建路径，但无法让它运行。请帮忙。我需要在运行配置中添加任何内容吗？ 这是Eclipse浏览器上的错误： HTTP Status 500 – Internal Server Error

异常报告类型

消息 javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver

描述 服务器遇到了一个意外情况，阻止它完成请求。

异常 org.apache.jasper.JasperException: javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:599) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:500) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

根本原因 javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:917) org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:846) org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:129) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

根本原因 java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver compute.DB.con(DB.java:21) org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:100) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

根本原因 java.lang.ClassNotFoundException: com.mysql.jdbc.Driver org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1951) org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1794) compute.DB.con(DB.java:21) org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:100) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

请注意，根本原因的完整堆栈跟踪在服务器日志中可用。 这是控制台输出： &gt; Mar 16, 2020 4:57:27 PM org.apache.catalina.core.StandardContext reload INFO: 正在重新加载名称为[/Mysql]的上下文 Mar 16, 2020 4:57:27 PM org.apache.catalina.core.StandardContext reload INFO: 重新加载名称为[/Mysql]的上下文已完成 Mar 16, 2020 4:57:41 PM org.apache.catalina.core.StandardWrapperValve invoke SEVERE: 在带有路径[/Mysql]的上下文中为servlet[jsp]提供服务时，抛出异常[javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver]，根本原因为 java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1951) at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1794) at compute.DB.con(DB.java:21) at org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:100) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 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:492) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:165) at org.apache.catalina.valves <details> <summary>英文:</summary> am trying to run simple code to connect with mysql. I m using eclipse and tomcat. have added mysql-connector-java-8.0.1.9.jar in Libraries: Libraries--&gt;mysql--&gt;mysql-connector-java-8.0.1.9.jar have been at it for several hours adding and removing mysql-connector-java-8.0.1.9.jar to build path cannot get it running. Please help. Do I need to add any thing in run configuration?? is the error on eclipse browser: HTTP Status 500 – Internal Server Error

Type Exception Report

Message javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception org.apache.jasper.JasperException: javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:599) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:500) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Root Cause javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:917) org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:846) org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:129) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Root Cause java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver compute.DB.con(DB.java:21) org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:100) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Root Cause java.lang.ClassNotFoundException: com.mysql.jdbc.Driver org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1951) org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1794) compute.DB.con(DB.java:21) org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:100) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

Note The full stack trace of the root cause is available in the server logs. is the output in console: &gt; Mar 16, 2020 4:57:27 PM org.apache.catalina.core.StandardContext reload INFO: Reloading Context with name [/Mysql] has started Mar 16, 2020 4:57:27 PM org.apache.catalina.core.StandardContext reload INFO: Reloading Context with name [/Mysql] is completed Mar 16, 2020 4:57:41 PM org.apache.catalina.core.StandardWrapperValve invoke SEVERE: Servlet.service() for servlet [jsp] in context with path [/Mysql] threw exception [javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver] with root cause java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1951) at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1794) at compute.DB.con(DB.java:21) at org.apache.jsp.regCheck_jsp._jspService(regCheck_jsp.java:100) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:477) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 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:492) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:165) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:1025) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:452) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1195) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:654) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:319) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.base/java.lang.Thread.run(Thread.java:834)

Try - 05 Trying to establish con in regCheck.jsp Con method called Try 5A Try 05a - Trying to connect is DB.java:

package compute;

import java.sql.Connection; import java.sql.DriverManager; import java.sql.Statement; import java.sql.*;

public class DB {

final static String DB_URL = &quot;jdbc:mysql://localhost:3306/new&quot;; final static String USER = &quot;admin&quot;; final static String PASS = &quot;admin&quot;;

public static Connection con() { System.out.println(&quot;Con method called Try 5A&quot;); Connection con; try { System.out.println(&quot;Try 05a - Trying to connect&quot;); DriverManager.registerDriver(new com.mysql.jdbc.Driver()); con = DriverManager.getConnection(DB_URL, USER, PASS); System.out.println(&quot;Try 05a- con established &quot;); return con; }catch(Exception e) { System.out.println(e); return null; } }

public static Statement st() { Statement stmt; try { stmt=DB.con().createStatement(); return null; }catch(Exception e) { System.out.println(e); return null; } } } is regCheck.jsp: &lt;%@page import=&quot;java.sql.Connection&quot; %&gt; &lt;%@page import=&quot;compute.DB&quot; %&gt; &lt;%@page import=&quot;java.sql.PreparedStatement&quot; %&gt;

&lt;%@ page language=&quot;java&quot; contentType=&quot;text/html; charset=ISO-8859-1&quot; pageEncoding=&quot;ISO-8859-1&quot;%&gt; &lt;!DOCTYPE html&gt; &lt;html&gt; &lt;head&gt; &lt;meta charset=&quot;ISO-8859-1&quot;&gt; &lt;title&gt;Insert title here&lt;/title&gt; &lt;/head&gt; &lt;body&gt; &lt;% String user = request.getParameter(&quot;username&quot;); System.out.println(&quot;Try - 05 Trying to establish con in regCheck.jsp&quot;); Connection con = DB.con(); System.out.println(&quot;Preparing Statement in regCheck.jsp&quot;); PreparedStatement p = con.prepareStatement(&quot;Insert into register(username)values(?)&quot;);

p.setString(1,user); System.out.println(&quot;user::&quot; +user);

int R = p.executeUpdate(); if(R!=0) response.sendRedirect(&quot;index.html&quot;); else response.sendRedirect(&quot;register.jsp&quot;);

%&gt;

&lt;/body&gt; &lt;/html&gt; </details> 答案1 0 JDBC驱动程序库在您的*运行时*CLASSPATH中丢失，即Tomcat在其中查找所需的类以执行已编译代码的CLASSPATH。 <details> <summary>英文:</summary> JDBC driver library is missing from your *runtime* CLASSPATH i.e. the CLASSPATH where Tomcat looks for the required classes in order to execute your compiled code. </details> 答案2 0 我将mysql-connector-java-8.0.19.jar添加到Tomcat 7.0/Lib中，现在它正常工作。 我从库中和所有地方都将它移除，它仍然可用。 我创建了一个新项目，使用相同的代码，而没有将mysql-connector-java-8.0.19.jar添加到任何库或构建路径中，它正常运行。 我在某个地方的YouTube上找到了将其添加到Tomcat的说明。 <details> <summary>英文:</summary> added mysql-connector-java-8.0.19.jar  to Tomcat 7.0/Lib and now it&#39;s working find. removed it from Library and everywhere and it works. created new project with the same code and without adding mysql-connector-java-8.0.19.jar to any library or build path, it&#39;s running fine. found the instruction to add to tomcat somewhere on youtube. </details>







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