与JSP一起使用的速度抛出javax.servlet.ServletException：java.lang.NoClassDefFoundError：

Question

我一直在尝试为我的软件创建一个管理面板。 我决定将速度模板语言（VTL）与JSP结合使用来创建动态页面。 但是，当我导入在程序中创建的具有VTL代码的Bean时，它将抛出javax.servlet.ServletException: java.lang.NoClassDefFoundError:并打印以下堆栈跟踪：

javax.servlet.ServletException: java.lang.NoClassDefFoundError: org/apache/velocity/context/Context
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:343)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

有根本原因

java.lang.NoClassDefFoundError: org/apache/velocity/context/Context
    java.lang.Class.getDeclaredConstructors0(Native Method)
    java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    java.lang.Class.getConstructor0(Unknown Source)
    java.lang.Class.getConstructor(Unknown Source)
    org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1223)
    org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1182)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2428)
    org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2434)
    org.apache.jasper.compiler.Node$Root.accept(Node.java:475)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Generator.generate(Generator.java:3490)
    org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:250)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:373)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:353)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:340)
    org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:646)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:357)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

我的JavaBean是：

package com.sarvika.cfnm.web;

import java.sql.*;
import java.io.*;

import org.apache.velocity.*;
import org.apache.velocity.app.VelocityEngine;

public class IndexGenerator {

    private final String JDBC_URL = "jdbc:mysql://127.0.0.1/coffeenet" ;
    private final String SQL_USER = "root" ;
    private final String SQL_PASS = "root" ;

    private final String VELOCITY_TEMPLATE_TABLE = "users_table.vm";
    private final String VELOCITY_CONTEXT_USERS_ARRAY = "usersList";

    private final String SELECT_QUERY = "SELECT AuthID FROM users ;" ;
    private final String COLUMN_ALIAS_USERS = "AuthID";

    private final File ADMIN_JSP = new File("WebContent/admin.jsp");

    public void generate() {

        VelocityEngine engine = new VelocityEngine();
        Template template = engine.getTemplate(VELOCITY_TEMPLATE_TABLE);
        VelocityContext context = new VelocityContext();

        Object [] users = getAllUsers();

        context.put(VELOCITY_CONTEXT_USERS_ARRAY, users);

        StringWriter jspData = new StringWriter();
        template.merge(context, jspData);

        try {

            BufferedWriter jspFileWriter = new BufferedWriter(new FileWriter(ADMIN_JSP));
            jspFileWriter.write(jspData.toString());
            jspFileWriter.close();

        } catch (IOException ex){           
        }

    }

    private Object [] getAllUsers() {

        Object [] users = null ;
        try {

            int counter = 0 ;
            Connection sqlConnection = DriverManager.getConnection(JDBC_URL, SQL_USER, SQL_PASS);
            Statement sqlStatement = sqlConnection.createStatement();
            ResultSet resultSet = sqlStatement.executeQuery(SELECT_QUERY);

            while ( resultSet.next() )              
                counter++;

            users = new Object [counter] ;

            resultSet = sqlStatement.executeQuery(SELECT_QUERY);

            for ( int i = 0 ; i < users.length ; i++ ) {
                resultSet.next();
                users[i] = resultSet.getString(COLUMN_ALIAS_USERS);
            }

        } catch (SQLException ex) {         
        }
        return users;

    }

}

JSP是：

<%@ 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>Insert title here</title>
</head>
<body>

    <jsp:useBean id="validator" class="com.sarvika.cfnm.main.Validator"></jsp:useBean>
    <jsp:useBean id="gen" class="com.sarvika.cfnm.web.IndexGenerator"></jsp:useBean>

    <center><img src="cfnm.png" align="top"></center>

    <%
        String userName = request.getParameter("userID");
        String password = request.getParameter("password");

        validator.setUserName(userName);
        validator.setPassword(password);
    %>

    <%=
        validator.check()
    %>

    <%
        if (validator.getValidation() == true) {
            gen.generate();
        }
    %>

</body>
</html>

我在哪里犯错。 我正在使用Eclipse Indigo IDE。 我搜索了该主题，发现我应该在WEB-INF目录中包含必需的JAR。 我已经这样做了，但是问题仍然存在。

Answer 1

应该在/ WEB-INF / lib目录中