为何跳转到servlet会有异常????-----急----- 我从一个jsp页面超链接到一个servlet中,然后在servlet中设置一个session变量,然后通过response.sendRedirect()方法跳转到另外一个jsp页面.不会爆错,但是有空值异常,请问是什么问题??? 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 <%@ page contentType="text/html; charset=GBK" %><%@page import="com.westaccp.*" %><html><head><title>success</title></head><body bgcolor="#ffccff"><h1>haha</h1><% Users u=(Users)session.getAttribute("users");%><h2>欢迎<%=u.getName()%></h2><a href="/myWeb/aaaa?a=2">跳转到index页面</a></body></html>跳转到这个servletpackage com.westaccp;import javax.servlet.*;import javax.servlet.http.*;import java.io.*;import java.util.*;public class Servlet1 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 { response.setContentType(CONTENT_TYPE); PrintWriter out = response.getWriter(); String a=request.getParameter("a"); if(a.equals("1")) { String name=request.getParameter("name"); String pwd=request.getParameter("pwd"); Users u=new Users(); u.setName(name); u.setPwd(pwd); HttpSession s=request.getSession(); s.setAttribute("users",u); response.sendRedirect("success.jsp"); } if(a.equals("2")) { Users u=new Users(); u.setName("hello"); u.setPwd("fine"); HttpSession s=request.getSession(); s.setAttribute("users1",u); response.sendRedirect("index.jsp"); } } //Process the HTTP Post request public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } //Clean up resources public void destroy() { }}跳转到下一个jsp<%@ page contentType="text/html; charset=GBK" %><%@page import="com.westaccp.*" %><html><head><title>index</title></head><body bgcolor="#ccffff"><h1>haha</h1><% Users u=(Users)session.getAttribute("users1");%><h2>»¶ӭ<%=u.getName()%></h2></body></html> //servlet……s.setAttribute("users",u);……//jsp<%Users u=(Users)session.getAttribute("users1");%>=====================细心啊 ...if(a.equals("1")) { String name=request.getParameter("name"); String pwd=request.getParameter("pwd");...我从你的页面上看,request.getParameter("name");你能获到值吗?你能获到那才叫真是奇怪乐!<a href="/myWeb/aaaa?a=2">跳转到index页面</a>就这个你是不能获到name和pwd的, response.sendRedirect() 方法不能傳遞session中的對象的。 Java变量的作用域和访问控制 大虾们看看问题在哪? 请大家推荐几个图形控件 简单输入问题,高手肯定遇到过。 JAVA怎样计算两个日期之间的差 $$$$讨论热门流行最吃香月薪高的编成语言$$$$ 急!Java Applet打印的问题,如何排版,并打印Applet区域内的部分(如果可用就给积分) javaIO、文件上传 哪位大哥帮帮小弟!!!!!!!! Java程序编译成功,但无法运行,请要出了什么问题?要如何修改? socket 广播问题!请高手进来指点一下 !谢谢了! java程序是使用unicode字符集编写的。这句话到底该怎么理解。←----高人看过来
<%@page import="com.westaccp.*" %>
<html>
<head>
<title>
success
</title>
</head>
<body bgcolor="#ffccff">
<h1>
haha
</h1>
<%
Users u=(Users)session.getAttribute("users");
%>
<h2>欢迎<%=u.getName()%></h2>
<a href="/myWeb/aaaa?a=2">跳转到index页面</a>
</body>
</html>
跳转到这个servlet
package com.westaccp;import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;public class Servlet1
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 {
response.setContentType(CONTENT_TYPE);
PrintWriter out = response.getWriter();
String a=request.getParameter("a");
if(a.equals("1"))
{
String name=request.getParameter("name");
String pwd=request.getParameter("pwd");
Users u=new Users();
u.setName(name);
u.setPwd(pwd);
HttpSession s=request.getSession();
s.setAttribute("users",u);
response.sendRedirect("success.jsp");
}
if(a.equals("2"))
{
Users u=new Users();
u.setName("hello");
u.setPwd("fine");
HttpSession s=request.getSession();
s.setAttribute("users1",u);
response.sendRedirect("index.jsp");
} } //Process the HTTP Post request
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
doGet(request, response);
} //Clean up resources
public void destroy() {
}
}跳转到下一个jsp<%@ page contentType="text/html; charset=GBK" %>
<%@page import="com.westaccp.*" %>
<html>
<head>
<title>
index
</title>
</head>
<body bgcolor="#ccffff">
<h1>
haha
</h1>
<%
Users u=(Users)session.getAttribute("users1");
%>
<h2>»¶ӭ<%=u.getName()%></h2>
</body>
</html>
……
s.setAttribute("users",u);
……//jsp
<%
Users u=(Users)session.getAttribute("users1");
%>
=====================
细心啊
if(a.equals("1"))
{
String name=request.getParameter("name");
String pwd=request.getParameter("pwd");
...
我从你的页面上看,request.getParameter("name");你能获到值吗?你能获到那才叫真是奇怪乐!
<a href="/myWeb/aaaa?a=2">跳转到index页面</a>就这个你是不能获到name和pwd的,