关于TOMCAT Error allocating a servlet instance错误问题，请帮助!

[luckhq]

我用的是tomcat5.0.19，jdk是jdk1.4 我按照“Servlet/JSP配置详解(非常基础) (3-2,753,jdbc)”所说的方法用jbuilder建立了一个工程test_servlet，在工程里建立了一个servlet，名字叫HelloWorld。
接着我把HelloWorld.java编译成class文件并放在了webapps\ROOT\WEB-INF\classes下面
我的webapps\ROOT\WEB-INF下的web.xml是这样写的：
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<display-name>Welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description>
<!-- JSPC servlet mappings start -->
<servlet>
<servlet-name>org.apache.jsp.index_jsp</servlet-name>
<servlet-class>org.apache.jsp.index_jsp</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>org.apache.jsp.index_jsp</servlet-name>
<url-pattern>/index.jsp</url-pattern>
</servlet-mapping>
<!-- JSPC servlet mappings end -->
<servlet>
<servlet-name>HelloWorld</servlet-name>
<servlet-class>HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorld</servlet-name>
<url-pattern>/servlet/HelloWorld</url-pattern>
</servlet-mapping>
</web-app>

当我点击http://localhost:8080/servlet/HelloWorld的时候系统就报错了，错误是这样的
javax.servlet.ServletException: Error allocating a servlet instance
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:164)
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:206)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:833)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:732)
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:619)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:688)
java.lang.Thread.run(Thread.java:536)


root cause

java.lang.NoClassDefFoundError: HelloWorld (wrong name: test_servlet/HelloWorld)
java.lang.ClassLoader.defineClass0(Native Method)
java.lang.ClassLoader.defineClass(ClassLoader.java:502)
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1677)
org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:900)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1350)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1230)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:164)
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:206)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:833)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:732)
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:619)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:688)
java.lang.Thread.run(Thread.java:536)

我真的不明白到底是怎么回事，这样的情况几天了都不清楚，郁闷死了。快请大家帮帮我

[fengyun1314]

是那个类没有找到，肯定是你的路径错了。