Question

index.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>REGISTRATION</title>
</head>
<body>
<form action="reg" method="post">
Name: <input type="text" name="user_name"><br>
EMAIL: <input type="text" name="user_email"><br>
PASSWORD: <input type="text" name="user_pass"><br>
<input type="submit"><br>
</form>
</body>
</html>



reg.java


import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class reg
 */
@WebServlet("/reg")
public class reg extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        String user_name = request.getParameter("user_name").toString();
        String user_email = request.getParameter("user_email").toString();
        String user_pass = request.getParameter("user_pass").toString();

            Connection con=null;
            try {
                Class.forName("com.mysql.jdbc.driver");
                con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test","root","root123");
                Statement st=con.createStatement();
                int c=st.executeUpdate("insert into test values('"+user_name+"','"+user_email+"','"+user_pass+"')");
                if(c>0){
                    out.println("REGISTERD");
                }
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
    }

}

显示例外情况一切都在项目..连接器，数据库，表如果用户相同的代码，它运行简单的Java代码但在servlet中显示ClassNotFoundException 帮我。谢谢！

以下是例外

java.lang.ClassNotFoundException：com.mysql.jdbc.driver at org.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1333）在 org.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1167） at java.lang.Class.forName0（Native Method）at reg.doPost中的java.lang.Class.forName（未知来源）（reg.java:47）在javax.servlet.http.HttpServlet.service（HttpServlet.java:648）at javax.servlet.http.HttpServlet.service（HttpServlet.java:729）at at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:291）在 org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:206）在 org.apache.tomcat.websocket.server.WsFilter.doFilter（WsFilter.java:52）在 org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:239）在 org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:206）在 org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:212）在 org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve.java:106）在 org.apache.catalina.authenticator.AuthenticatorBase.invoke（AuthenticatorBase.java:502）在 org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:141）在 org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:79）在 org.apache.catalina.valves.AbstractAccessLogValve.invoke（AbstractAccessLogValve.java:616）在 org.apache.catalina.core.StandardEngineValve.invoke（StandardEngineValve.java:88）在 org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:521）在 org.apache.coyote.http11.AbstractHttp11Processor.process（AbstractHttp11Processor.java:1096）在 org.apache.coyote.AbstractProtocol $ AbstractConnectionHandler.process（AbstractProtocol.java:674）在 org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java:1500）在 org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.run（NioEndpoint.java:1456） at java.util.concurrent.ThreadPoolExecutor.runWorker（Unknown Source） at java.util.concurrent.ThreadPoolExecutor $ Worker.run（Unknown Source）在 org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run（TaskThread.java:61）在java.lang.Thread.run（未知来源）

Answer 1

如果它在Eclipse中运行，则表示您在项目的类路径中有MySql jdbc dirver jar，但它不适用于您的Web应用程序。

项目类路径（构建路径）与部署时Web应用程序的类路径不同。并非所有项目类路径上的jar都会自动导出。

通常WEB-INF/lib中的jars可用于Web应用程序，但不包含其中的jar。

您应该将MySql jdbc驱动程序jar放在WEB-INF/lib中，或者将其添加到Servlet容器的lib文件夹中（在您的情况下通过异常堆栈跟踪判断Tomcat）。

JSP JDBC SERVLET显示classnotfound异常....一切正确

1 个答案: