为利用application在服务器端公用和可以暂时保存数据的特点，设计一个记事本程序
为利用application在服务器端公用和可以暂时保存数据的特点，设计一个记事本程序。码调试报错。请指教
index.jsp中的主要代码：
<body>
<form action=notepad.jsp method="post" name=form>
标题：<input type="text" size=16 name="title"/>
<p>请输入你的留言：<br>
<textarea rows="8" cols="40" name="content" wrap="phsical"></textarea>
<br>
<input type="submit" value="提交" name="submit">
</form>
</body>
notepad.jsp中的主要代码：
<body>
<%
Date date=new Date();
String datetime=date.toLocaleString();
String title=request.getParameter("title");
String message=request.getParameter("content");
//将各项整合为一个字符串
String s=title+"#"+message+"#"+datetime;
//从application中获取原有的留言内容
Vector v=(Vector)application.getAttribute("mess");
v.add(s);
application.setAttribute("mess",v);
Vector vv=(Vector)application.getAttribute("mess");
//下面的循环从VV中取出每条留言，并分析分项内容
for(int i=0;i<vv.size();i++)
{
String messages=(String)vv.elementAt(i);
StringTokenizer fenxi=new StringTokenizer(messages,"#");
int j=0,m=i+1;
String str[]=new String[3];
//循环分析messages字符串的内容
while(fenxi.hasMoreTokens())
{
str[j]=fenxi.nextToken();
byte a[]=str[j].getBytes("ISO-8859-1");
str[j]=new String(a);
j++;
}
out.print("<center>");
out.print("********************************<br>");
out.print("<Table border>");
out.print("<tr>");
out.print("<td>第"+m);
out.print("楼 标题："+str[0]);
out.print(" 时间："+str[2]);
out.print("</td>");
out.print("</tr>");
out.print("<tr>");
out.print("<td>");
out.print("内容："+str[1]);
out.print("</td>");
out.print("</tr>");
out.print("</Table>");
out.print("</center>");
}
%>
</body>
报错：
HTTP Status 500 -
--------------------------------------------------------------------------------
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause
java.lang.NullPointerException
org.apache.jsp.notepad_jsp._jspService(notepad_jsp.java:95)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.20 logs.
--------------------------------------------------------------------------------
Apache Tomcat/6.0.20
搜索更多相关主题的帖子:
title method action name
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有人吗？
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有人吗
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Vector v=(Vector)application.getAttribute("mess");
if(v==null){
v= new Vector();
}
这下面加一个这个就OK了
原理是 当mess没有信息时 是一个null值
null是不能add属性的
----------------解决方案--------------------------------------------------------