英文:
javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/mysql/jdbc/Driver
问题
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-->mysql-->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：
> 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>
I am trying to run simple code to connect with mysql. I m using eclipse and tomcat.
I have added mysql-connector-java-8.0.1.9.jar in Libraries:
Libraries-->mysql-->mysql-connector-java-8.0.1.9.jar
I 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??
This 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.
This is the output in console:
> 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
This 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 = "jdbc:mysql://localhost:3306/new";
final static String USER = "admin";
final static String PASS = "admin";
public static Connection con() {
System.out.println("Con method called Try 5A");
Connection con;
try {
System.out.println("Try 05a - Trying to connect");
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
con = DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("Try 05a- con established ");
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;
}
}
}
This is regCheck.jsp:
<%@page import="java.sql.Connection" %>
<%@page import="compute.DB" %>
<%@page import="java.sql.PreparedStatement" %>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
String user = request.getParameter("username");
System.out.println("Try - 05 Trying to establish con in regCheck.jsp");
Connection con = DB.con();
System.out.println("Preparing Statement in regCheck.jsp");
PreparedStatement p = con.prepareStatement("Insert into register(username)values(?)");
p.setString(1,user);
System.out.println("user::" +user);
int R = p.executeUpdate();
if(R!=0)
response.sendRedirect("index.html");
else
response.sendRedirect("register.jsp");
%>
</body>
</html>
</details>
# 答案1
**得分**: 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>
The 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
**得分**: 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>
I added mysql-connector-java-8.0.19.jar to Tomcat 7.0/Lib and now it's working find.
I removed it from Library and everywhere and it works.
I created new project with the same code and without adding mysql-connector-java-8.0.19.jar to any library or build path, it's running fine.
I found the instruction to add to tomcat somewhere on youtube.
</details>
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