我把程序放在
    E:\servlet
         WEB-INF
             classes
                servlet
                     此文件夹下有一个Servlet1.classServer.XML 加入下条语句
<Context debug="0" docBase="E:\servlet" path="/servlet" reloadable="true" crossContext="true"></Context>Web.XML配置如下
 <servlet>
    <servlet-name>servlet1</servlet-name>
    <servlet-class>servlet.Servlet1</servlet-class>
 </servlet>
 <servlet-mapping>
    <servlet-name>servlet1</servlet-name>
    <url-pattern>/servlet1</url-pattern>
 </servlet-mapping>输入http://localhost:8080/servlet/servlet1 
提示HTTP Status 404 - /servlet/servlet1
http://localhost:8080 能正常运行。