java - NoClassDefFoundError : Tomcat 7 unable to load classes from jar

Question

有点初学者的问题，但不幸的是搜索对我没有帮助。我在 java 中创建了一个模拟 dieroll 的简单类，如下所示:

package java.com.game.util;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class Dice {

    private static Random randomGenerator = new Random();

    public static int rollOne(){
        return randomGenerator.nextInt(6)+1;
    }

    public static List<Integer> roll(int amountOfDice){
        List<Integer> rolls = new ArrayList<Integer>();
        for (int i = amountOfDice ; i > 0; i--){
            rolls.add(rollOne());
        }
        return rolls;
    }

}

之所以用“java”打包，是因为maven。 Dice.class 包含在 WEB-INF/lib 目录下的 Game-0.1-SNAPSHOT.jar 中。

我正在尝试在以下 jsp 中使用 Dice:

<H1>Test</H1>
<%= java.com.game.util.Dice.rollOne() %>

这是发生的错误:

org.apache.jasper.JasperException: An exception occurred processing JSP page /game/index.jsp at line 2

1: <H1>Some Heading</H1>
2: <%= java.com.game.util.Dice.rollOne() %>


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:455)
    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:728)

root cause

javax.servlet.ServletException: java.lang.NoClassDefFoundError: java/com/game/util/Dice
    org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:912)
    org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:841)
    org.apache.jsp.game.index_jsp._jspService(index_jsp.java:69)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    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:728)

root cause

java.lang.NoClassDefFoundError: java/com/game/util/Dice
    org.apache.jsp.game.index_jsp._jspService(index_jsp.java:63)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    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:728)

我做错了什么？

Answer 1

这是预期的 Tomcat 7 行为。一些打包被Tomcat限制了。 您可以在以下位置找到无法加载的包/类列表

$CATALINA_BASE/conf/catalina.properties

有 java. 模式。