HTTP Status 500 - Error,该如何处理_J2EE

HTTP Status 500 - Error
如题，第一次用myeclipse 就出问题了，唉、、、
import java.io.IOException;
import java.io.OutputStream;
import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class ServletDemo1 extends GenericServlet{

@Override
public void service(ServletRequest req, ServletResponse res)
throws ServletException, IOException {
OutputStream out = res.getOutputStream();
out.write("Servlet!!!!".getBytes());
}

}[/code]
这是Java代码、、、
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
  version="3.0">
  <servlet>
   <servlet-name>ServletDemo1</servlet-name>
   <servlet-class>/Web_Servlet/src/com/fox/ServletDemo1</servlet-class>
  </servlet>

  <servlet-mapping>
   <servlet-name>ServletDemo1</servlet-name>
   <url-pattern>/ServletDemo1</url-pattern>
  </servlet-mapping>

  <welcome-file-list>
      <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>

</web-app>
这是配置文件，好了，然后我把server启动，在IE里面访问http://localhost:8080/Web_Servlet/ServletDemo1就出问题了。
首先，ie里面显示500错误，服务器那段抛出java.lang.ClassNotFoundException: /Web_Servlet/src/com/fox/ServletDemo1这个异常、、、
百度了好多，实在搞不明白，求大神啊！！！！！！
------解决思路----------------------

 
<servlet>
  	<servlet-name>ServletDemo1</servlet-name>
  	<servlet-class>/Web_Servlet/src/com/fox/ServletDemo1</servlet-class>
 </servlet>

红色部分是JAVA类,正确应该是:
<servlet>
<servlet-name>ServletDemo1</servlet-name>
<servlet-class>com.fox.ServletDemo1</servlet-class>
</servlet>