请教一下：在运行jsp页，总是出现这个提示:(

此页源代码：
而且连接池已检查过了，没有问题啊？
<html>
<head>
<title>管理界面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<style type="text/css">

</style>
</head><body bgcolor="#FFFFFF" text="#000000">
<div align="center">管理界面
  <form name="form1" method="post" action="addadmin.jsp">
    添加管理员
    <input type="text" name="adminname" size="20" maxlength="20">
    <input type="submit" name="pub_adda" value="添加">
    <input type="hidden" name="action" value="addadmin">
  </form>

  <table width="500" border="0" cellpadding="1" cellspacing="1">
    <tr bgcolor="#B6B7C9">
      <td width="43">
        <div align="center">ID</div>
      </td>
      <td width="93">
        <div align="center">用户名</div>
      </td>
      <td width="68">
        <div align="center">Super</div>
      </td>
      <td width="68">
        <div align="center">主版区管理</div>
      </td>
      <td width="68">
        <div align="center">公告发布</div>
      </td>
      <td width="68">
        <div align="center">用户管理</div>
      </td>
      <td width="70">
        <div align="center">修改</div>
      </td>
    </tr>

  </table>
  <hr width="500">
  <form name="addb" method="post" action="addboard_ok.jsp">
    <table width="272" border="0" align="center">
      <tr>
        <td colspan="2">
          <div align="center">添加版区</div>
        </td>
      </tr>
      <tr>
        <td width="90">
          <div align="right">名称（中）：</div>
        </td>
        <td width="172">
          <input type="text" name="boardname" size="20" maxlength="20">
        </td>
      </tr>
      <tr>
        <td width="90">
          <div align="right">名称（英）：</div>
        </td>
        <td width="172">
          <input type="text" name="eboardname" size="20" maxlength="20">
        </td>
      </tr>
      <tr>
        <td width="90">
          <div align="right">斑竹：</div>
        </td>
        <td width="172">
          <input type="text" name="bmaster" size="20" maxlength="20">
        </td>
      </tr>
      <tr>
        <td width="90">
          <div align="right">版区属性：</div>
        </td>
        <td width="172">
          <select name="attrib">
            <option value="1">中文版区</option>
            <option value="2">英文版区</option>
          </select>
        </td>
      </tr>
      <tr>
        <td width="90">
          <div align="right">序：</div>
        </td>
        <td width="172">
          <input type="text" name="xu" size="3" maxlength="3">
        </td>
      </tr>
      <tr>
        <td colspan="2">
          <div align="center">
            <input type="submit" name="pub_addb" value="添加">
            <input type="reset" name="Submit2" value="重填">
          </div>
        </td>
      </tr>
    </table>
  </form>
  <table width="371" border="0" cellpadding="1" cellspacing="1">
    <tr bgcolor="#B6B7C9">
      <td width="161">
        <div align="center"><font color="#5E6180"><b>版区名称</b></font></div>
      </td>
      <td width="155">
        <div align="center"><font color="#5E6180"><b>斑竹</b></font></div>
      </td>
      <td width="45">
        <div align="center"><font color="#5E6180"><b>删除</b></font></div>
      </td>
    </tr>

  </table>
</div>
<p><CENTER><a href="logout.jsp">退出系统</a></CENTER></p>
</body>
</html>

由于不能一次全发，分为三部分，程序的第一部分；
<%@ page language="java" %>
<%@ page import="java.sql.*"%>
<%@ page import="java.io.*" %>
<%@ page import="java.util.*" %>
<jsp:useBean id="DBconnBean" scope="page" class="db.DbConnection" />
<jsp:useBean id="ReOutputBean" scope="page" class="db.ReOutput" />
<%@ page contentType="text/html;charset=gb2312" %><%
String ID = null;
String name = null;
String nick = null;
String post = null;
ID = (String) session.getValue("ID");
name = (String) session.getValue("name");
nick =(String) session.getValue("nick");
post = (String) session.getValue("post");if (ID!=null && name!=null && nick!=null) {
  DBconnBean.openConnection();
  String SQL = "";
  ResultSet rs;
  String bid = request.getParameter("bid");
// by zzl at 2002.03.02
bid =db.DbConnection.bytes2gb(bid);%>
<html>
<head>
<title>虚拟社区</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<style>

</style>
<script language="JavaScript" src="win.js"></script>
</head><body bgcolor="#FFFFFF" text="#000000" leftmargin="0" topmargin="0">
<%
  int usuper = 0;
  int ubulletin = 0;
  SQL = "select super,bulletin from adminuser where UID="+ ID;
  rs =  DBconnBean.executeQuery(SQL);
  if (rs.next()) {
    usuper = rs.getInt("super");
    ubulletin = rs.getInt("bulletin");
  }
  rs.close();  if (bid != null && bid.length()>0) {
  int boardID = 0;
  String boardsname = "";
  String eboardsname = "";
  String bsmaster = "";
  String boardgg = "";
  int attrib = 1;
  boolean imaster = false;
  SQL = "select * from boards where ID="+ bid;
  rs =  DBconnBean.executeQuery(SQL);
  if (rs.next()) {
    boardID = rs.getInt("boardID");
    boardsname = rs.getString("boardsname");
// by zzl at 2002.03.02
boardsname =db.DbConnection.bytes2gb(boardsname);
    eboardsname = rs.getString("eboardsname");
// by zzl at 2002.03.02
eboardsname =db.DbConnection.bytes2gb(eboardsname);
bsmaster = rs.getString("bsmaster");
// by zzl at 2002.03.02
bsmaster =db.DbConnection.bytes2gb(bsmaster);
boardgg = rs.getString("boardgg");
// by zzl at 2002.03.02
boardgg =db.DbConnection.bytes2gb(boardgg);
    attrib = rs.getInt("attrib");
  }
  rs.close();  StringTokenizer masterok = new StringTokenizer(bsmaster,",");
  //String token[] = new String[4];
  //int i = 0;

  while(masterok.hasMoreTokens()) {
   if (name.equals(masterok.nextToken())) {
    imaster = true;
   }
  //token[i] = tok.nextToken();
  //i++;
  }  String echomaster = "";
  String echoname = "";
  StringTokenizer echomasters = new StringTokenizer(bsmaster,",");
  //String token[] = new String[4];
  //int i = 0;

程序的第二部分：
  while(echomasters.hasMoreTokens()) {
     echoname = echomasters.nextToken();
     echomaster = echomaster + "<a href='userinfo.jsp?uname="+ echoname +"'>"+ echoname +"</a>,";
   }


   // if (bsmaster.equals(name)) {
//   imaster = true;
//  }  int i;
  int allCol = 0;
  int ipage = 20; //分页单位
  int allpage = 1; //总页数
  int pages = 1; //接受的页码变量
  int cpage = 1; //当前页
  int spage = 1; //开始页  String pagesql = "select count(*) as total from forum where board = "+ bid +" and new=1";
  //取总文章数
  ResultSet pagers = DBconnBean.executeQuery(pagesql);
  if (pagers.next()) {
  allCol = pagers.getInt("total");
  }
  pagers.close();  //获得总页面数
  allpage = (int)Math.ceil((allCol + ipage-1) / ipage);  //判断参数pages是否为空
  if (request.getParameter("pages")==null || request.getParameter("pages").length() == 0) {
  pages = 1;
  } else {
  pages = new Integer(request.getParameter("pages")).intValue();
  }  //判断当前页
  if(pages > allpage){ // pages == 0
  cpage = 1;
  } else {
  cpage = pages;
  }  //判断起始页
  spage=(cpage-1)*ipage;  // by zzl at 2002.03.01 SQL = "select * from forum where board = "+ bid +" and new=1 order by lasttime desc limit "+ spage +","+ ipage;
  SQL = "select top " + ipage + " * from forum where board = "+ bid +" and new=1 order by lasttime desc";
  rs = DBconnBean.executeQuery(SQL);
  //int cu=1;
%>

<jsp:include page="headeradv.jsp" flush="true" />

<table width="615" border="0" align="center" cellpadding="0" cellspacing="0">
  <form name="formt1" method="post" action="searchforum.jsp">
  <INPUT TYPE="hidden" name="bid" value="<%=bid%>">
    <tr bgcolor="#EEF3F9">
      <td width="61" class="bt" height="11">版面公告：</td>
      <td width="296" height="11"><marquee><span class="bt"><%=boardgg%></span></marquee></td>
      <td width="258" class="bt" height="11">
        <div align="right">文章查找
          <input type="text" name="zhuti" size="10">
          <select name="tj">
            <option value="title" selected>主题</option>
            <option value="name">姓名</option>
          </select>
          <input type="image" border="0" name="imageField" src="images/search.gif" width="50" height="19">
        </div>
      </td>
    </tr>
  </form>
</table>


<table width="615" border="0" align="center" cellpadding="1" cellspacing="1">
<form name="formt2" method="post" action="tiaozhuan.jsp">
<INPUT TYPE="hidden" name="bid" value="<%=bid%>">
<INPUT TYPE="hidden" name="pages" value="<%=pages%>">
  <tr>
      <td class="bt" width="419"><%=boardsname%>(<%=eboardsname%>) <a href="javascript:view('jrzc.jsp?bid=<%=bid%>');">加进珍藏</a> <a href="jinghua2.jsp?boardID=<%=boardID%>&bid=<%=bid%>">精华区</a> <a href="javascript:view1('ydy.jsp?BID=<%=bid%>');">订阅</a> <% if (imaster) { out.print("<a href=javascript:view('xggg.jsp?bid="+ bid +"');>修改版面公告</a> <a href='unpostconf.jsp?bid="+ bid +"'>封用户POST权限</a>");}%></td>  <td width="189" class="bt">
        <div align="right">跳到第
          <input type="text" name="recid" size="1">
          主题 <% out.print(spage+1);%>-<%out.print(spage+ipage);%>，共<%=allCol%>主题</div>
      </td>
  </tr>
  </form>
</table>

程序的第三部分
<table width="615" border="0" align="center" cellpadding="0" cellspacing="0">
  <tr>
    <td width="396" class="bt">版主：<%out.print(echomaster.substring(0,echomaster.length()-1));%></td>
    <td width="219" class="bt">
      <div align="right"><font color="#FF0000"><% if ((attrib==1 || attrib==3) && post.equals("0")) {%>[<a href="post.jsp?bid=<%=bid%>"><font color="#FF0000">发表</font></a>]<%}else {
  if (attrib==2 && (usuper==1 || ubulletin==1)) {
      %>
  [<a href="post.jsp?bid=<%=bid%>"><font color="#FF0000">发表</font></a>]
  <%
  }
  }%> [论坛阅读] <% if (cpage>1) { %> [<a href="right.jsp?bid=<%= bid%>&pages=<%= cpage-1 %>"><font color=#FF0000>上一页</font></a>] <% } else { out.print("[上一页] ");} if (cpage<allpage) { %> [<a href="right.jsp?bid=<%= bid%>&pages=<%= cpage+1 %>"><font color=#FF0000>下一页</font></a>]<% } else { out.print("[下一页]");}%></font></div>
    </td>
  </tr>
</table>

<table width="615" border="0" align="center" cellpadding="1" cellspacing="1">
  <tr bgcolor="#355397">
    <td width="26">
      <div align="center"><font color="#FFFFFF"><span class="bt">回复</span></font></div>
    </td>
    <td width="27">
      <div align="center"><font color="#FFFFFF"><span class="bt">表情</span></font></div>
    </td>
    <td width="334">
      <div align="center"><font color="#FFFFFF"><span class="bt">题目</span></font></div>
    </td>
    <td width="110">
      <div align="center"><font color="#FFFFFF"><span class="bt">发表人</span></font></div>
    </td>
    <td width="102">
      <div align="center"><font color="#FFFFFF"><span class="bt">时间</span></font></div>
    </td>
  </tr>
  <%
  int i1 = 1;
  int n = 2;
  while (rs.next()) {
  %>
  <tr bgcolor="<% if ((i1 %= n)==1) {out.print("#EEF3F9");} else { out.print("#E1EAF4");}%>">
  
    <td width="26"><CENTER><span class="bt"><% int re=rs.getInt("re"); if (re==0) {out.print(db.DbConnection.bytes2gb(rs.getString("artsize")));} else { out.print("<font color=#ff0000>[+"+ re +"]<font>");}%></span></CENTER></td>
    <td width="27"><CENTER><img src="images/<%out.print(rs.getInt("bq"));%>.gif"></CENTER></td>
    <td width="334"><a href="showdoc.jsp?bid=<%=bid%>&recid=<%out.print(rs.getInt("id"));%>&pages=<%=pages%>" title ="点击：<%out.print(rs.getInt("click"));%>"><%String s=rs.getString("title");s=db.DbConnection.bytes2gb(s);out.print(s);%></a><% if (rs.getInt("jd") == 1) { out.print("<font color=#FF0000><span class=bt>荐</span></font>");}%></td>
    <td width="110"><CENTER><a href="userinfo.jsp?UID=<%out.print(rs.getInt("UID"));%>"><%out.print(db.DbConnection.bytes2gb(rs.getString("name")));;%></a></CENTER></td>
    <td width="102"><CENTER><%out.print(db.DbConnection.bytes2gb(rs.getString("time")).substring(5,16));%></CENTER></td>
  </tr>
  <%
  i1++;
  }
  %>
</table>

<table width="615" border="0" align="center" cellpadding="0" cellspacing="0">
  <tr>
    <td width="396"> </td>
    <td width="219" class="bt">
      <div align="right"><font color="#FF0000"><% if ((attrib==1 || attrib==3) && post.equals("0")) {%>[<a href="post.jsp?bid=<%=bid%>"><font color="#FF0000">发表</font></a>]<%}else {
  if (attrib==2 && (usuper==1 || ubulletin==1)) {
      %>
  [<a href="post.jsp?bid=<%=bid%>"><font color="#FF0000">发表</font></a>]
  <%
  }
  }%> <% if (cpage>1) { %> [<a href="right.jsp?bid=<%= bid%>&pages=<%= cpage-1 %>"><font color=#FF0000>上一页</font></a>] <% } else { out.print("[上一页] ");} if (cpage<allpage) { %> [<a href="right.jsp?bid=<%= bid%>&pages=<%= cpage+1 %>"><font color=#FF0000>下一页</font></a>]<% } else { out.print("[下一页]");}%></font></div>
    </td>
  </tr>
</table>

<%
  }
  else {
    out.print(ReOutputBean.ReOutput(false,"参数错误！","javascript:history.go(-1);"));
  }
%>
</body>
</html>
<%
  DBconnBean.close();
}
else {
  out.println("错误！你已被系统弹出！");
}
%>

这里：if (request.getParameter("pages")==null || request.getParameter("pages").length() == 0) {
  pages = 1;
  } else {
  pages = new Integer(request.getParameter("pages")).intValue();
  }
其中：
request.getParameter("pages").length() == 0)
在最开始时
request.getParameter("pages")的值是null使用length（）方法，会出现异常。

stupidball(小菜鸟) 说的这种情况应该不是，我测试过，这种情况不会发生空指针例外。因为它如果为null他将不会执行||后面的表达式。
贴出来的代码中我还没有发现会发生上面的错误，会不会是你<jsp:include page="headeradv.jsp" flush="true" />
中的headeradv.jsp中的错误，这个文件好像与该页没有关系，是不是显示广告的一个页面，先去掉再试试～！

把
if (request.getParameter("pages")==null || request.getParameter("pages").length() == 0)
改为
String pages=(String)request.getParameter("pages");
if(pages==null||pages.length()==0)

很遗憾，还是不行-->1.按照 yuanzi(远子) 的方法，把<jsp:include page="headeradv.jsp" flush="true" />给注释掉，出现“该页无法显示！”2.另一种方法，对if (request.getParameter("pages")==null || request.getParameter("pages").length() == 0)
进行改写，则会出现下列错误提示：
A Servlet Exception Has Occurred
org.apache.jasper.JasperException: Unable to compile class for JSPNote: sun.tools.javac.Main has been deprecated.
g:\tomcat\work\localhost\bbs\_0002fright_0002ejspright_jsp_4.java:691: 'try' without 'catch' or 'finally'.
                else {
                ^
g:\tomcat\work\localhost\bbs\_0002fright_0002ejspright_jsp_4.java:691: 'else' without 'if'.
                else {
                ^
g:\tomcat\work\localhost\bbs\_0002fright_0002ejspright_jsp_4.java:696: Type expected.
        } catch (Throwable t) {
          ^
3 errors, 1 warning at org.apache.jasper.compiler.Compiler.compile(Compiler.java:294)
at org.apache.jasper.servlet.JspServlet.doLoadJSP(JspServlet.java:478)
at org.apache.jasper.servlet.JasperLoader12.loadJSP(JasperLoader12.java:146)
at org.apache.jasper.servlet.JspServlet.loadJSP(JspServlet.java:449)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.loadIfNecessary(JspServlet.java:159)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:171)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:328)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:407)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:251)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:196)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:464)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:242)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:975)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2041)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:414)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:975)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:159)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:818)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:897)
at java.lang.Thread.run(Thread.java:536)

很遗憾，问题依然存在:(问题一：把“<jsp:include page="headeradv.jsp" flush="true" />
”给注释掉，出现错误提示信息-->该页无法显示；问题二：如果把if(request.getParameter("pages"==null || request.getParameter("pages").length()==0)改成-->String pages=(String)request.getParameter("pages");
if(pages==null||pages.length()==0)则会出现报错信息：A Servlet Exception Has Occurred
org.apache.jasper.JasperException: Unable to compile class for JSPNote: sun.tools.javac.Main has been deprecated.
g:\tomcat\work\localhost\bbs\_0002fright_0002ejspright_jsp_4.java:691: 'try' without 'catch' or 'finally'.
                else {
                ^
g:\tomcat\work\localhost\bbs\_0002fright_0002ejspright_jsp_4.java:691: 'else' without 'if'.
                else {
                ^
g:\tomcat\work\localhost\bbs\_0002fright_0002ejspright_jsp_4.java:696: Type expected.
        } catch (Throwable t) {
          ^
3 errors, 1 warning at org.apache.jasper.compiler.Compiler.compile(Compiler.java:294)
at org.apache.jasper.servlet.JspServlet.doLoadJSP(JspServlet.java:478)
at org.apache.jasper.servlet.JasperLoader12.loadJSP(JasperLoader12.java:146)
at org.apache.jasper.servlet.JspServlet.loadJSP(JspServlet.java:449)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.loadIfNecessary(JspServlet.java:159)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:171)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:328)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:407)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:251)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:196)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:464)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:242)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:975)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2041)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.valves.ValveBase.invokeNext(ValveBase.java:242)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:414)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:975)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:159)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:977)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:818)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:897)
at java.lang.Thread.run(Thread.java:536)

调试易

请教一下：在运行jsp页，总是出现这个提示:(

解决方案 »