在下写了两个Servlet，想第一个跳到第二个，但是运行后抛出这样的错误：
type： Exception report
message：
description：The server encountered an internal error () that prevented it from fulfilling this request.
exception：
java.lang.NullPointerException
ex3_8.UserServlet2.doGet(UserServlet2.java:34)
ex3_8.UserServlet2.doPost(UserServlet2.java:88)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
ex3_8.UserServlet1.doGet(UserServlet1.java:27)
ex3_8.UserServlet1.doPost(UserServlet1.java:34)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
源代码：
customer.html
<html>
<head> <title> 用户详细信息 </title> </head>
<body>
<form method=post action= "/ServletModule/userservlet1 ">
<h1 align=center> 欢迎来到 Shop Stop </h1>
请您输入用户ID以显示您的详细信息:
<br>
<input type=text name=txtuserid>
<br/>
<input type=submit value= "提交 ">
</form>
</body>
</html>
UserServlet1:
package ex3_8;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class UserServlet1 extends HttpServlet {
private static final String CONTENT_TYPE = "text/html; charset=GBK ";
//Initialize global variables
public void init() throws ServletException {
}
//Process the HTTP Get request
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
String uid=request.getParameter( "txtuserid ");
response.setContentType(CONTENT_TYPE);
PrintWriter out = response.getWriter();
ServletContext context=getServletContext();
context.setAttribute( "UserId ",uid);
RequestDispatcher dispatcher=request.getRequestDispatcher( "/userservlet2 ");
if(dispatcher==null){
response.sendError(response.SC_NO_CONTENT);
}
dispatcher.forward(request,response);