求助；jsp中只分页，只能看见第一页，后面的页看不见？

Question

int dipage=1;//当前页码默认值
String pages=request.getParameter("dipage");
if(pages==null)
{
pages="1";
}
try
{
dipage=Integer.parseInt(pages);
}
catch(Exception e)
{
dipage=1;
}
int countRecord=0;//纪录条数
   int countPageRecord=0;   //每页记录数
   int countPage=0;//总页数
   countPageRecord=15;//设置每页记录数
   rs.last();
   countRecord=rs.getRow();
   if(countRecord/countPageRecord==0)
    countPage=countRecord/countPageRecord;
else
countPage=countRecord/countPageRecord+1;
if((dipage-1)*countPageRecord==0)
rs.beforeFirst();
else
rs.absolute((dipage-1)*countPageRecord);
   
if(rs.next()==false)
{
out.print("没有符合条件的");
out.print(sql);
} else{ 
rs.beforeFirst();

out.print("<table width=96% border=1 align=center cellpadding=0 cellspacing=0 bordercolorlight=#215594 bordercolordark=#FFFFFF>");
out.print("<tr>");
out.print("<td width=18% height=25 background=images/BG2.gif>学号</td>");
out.print("<td width=15% height=25 background=images/BG2.gif>姓名</td>");
out.print("<td width=35% height=25 background=images/BG2.gif>学院</td>");
out.print("<td width=12% height=25 background=images/BG2.gif>是否投保</td>");
out.print("<td width=20% height=25 background=images/BG2.gif>查看</td>");
out.print("</tr>");
int i=0;
String no="";
 while(rs.next()){
 no=rs.getString("number");
 out.print("<tr>");
out.print("<td height=25>"+no+"</td>");
out.print("<td height=25>"+rs.getString(4)+"</td>");
out.print("<td height=25>"+rs.getString(1)+"</td>");
out.print("<td height=25>"+rs.getString(8)+"</td>");
out.print("<td height=25>");
out.print("<a href=teacher_find_2.jsp?number="+no+">详细信息</a>");
out.print("</td>");
out.print("</tr>");
i++;
if(i>=countPageRecord) break;
}
out.print("<tr><td colspan=8 align=center>");
out.print("共"+countRecord+"条记录,共"+countPage+"页,当前第"+dipage+"页，每页"+countPageRecord+"条记录,");
if(dipage==1);//首页
else//当前不是首页
{
out.print("<a href=teacher_find_fy.jsp?dipage=1>首页</a>,");
out.print("<a href=teacher_find_fy.jsp?dipage="+(dipage-1)+">上一页</a>,");
}
if(dipage==countPage);//是末页
else
{
out.print("<a href=teacher_find_fy.jsp?dipage="+(dipage+1)+">下一页</a>,");
out.print("<a href=teacher_find_fy.jsp?dipage="+countPage+">末页</a>,");
}

Answer 1

catch(Exception e)
{
dipage=1;
}
问题在这里，肯定是出错了catch(Exception e)
{
dipage=1;
out.print(e....);
}

Answer 2

补充一下．等我翻下一页的时候报的错误是：java.lang.NullPointerException

Answer 3

我试了把rs.absolute((dipage-1)*countPageRecord+1);设置为rs.absolute(n);//n为具体数字都没有错误．但是一但翻页就发生了错误．我修改过如下．但是仍然和原来的错误一样
 int countRecord=0;//纪录条数
   int countPageRecord=0;  //每页记录数
   int countPage=0;//总页数
   countPageRecord=15;//设置每页记录数
   rs.last();
   countRecord=rs.getRow();
   if(countRecord/countPageRecord==0)
   countPage=countRecord/countPageRecord;
else
countPage=countRecord/countPageRecord+1;
  String receive_page=request.getParameter("id");
  
    int dipage=1;//当前页码数默认为1
    if(receive_page==null)
        {
          dipage=1;
        }
    else
        {
          dipage=Integer.parseInt(receive_page);
  if(dipage<=0)
  dipage=1;
 
        }
if(dipage>countPage)
{
dipage=countPage;
}
if((dipage-1)*countPageRecord==0)
rs.beforeFirst();
else
rs.absolute((dipage-1)*countPageRecord+1);
  
/*if(rs.next()==false)
{
out.print("没有符合条件的");
out.print(sql);
}else{ */
out.print("<table width=96% border=1 align=center cellpadding=0 cellspacing=0 bordercolorlight=#215594 bordercolordark=#FFFFFF>");
out.print("<tr>");
out.print("<td width=18% height=25 background=images/BG2.gif>学号</td>");
out.print("<td width=15% height=25 background=images/BG2.gif>姓名</td>");
out.print("<td width=35% height=25 background=images/BG2.gif>学院</td>");
out.print("<td width=12% height=25 background=images/BG2.gif>是否投保</td>");
out.print("<td width=20% height=25 background=images/BG2.gif>查看</td>");
out.print("<td>"+receive_page+"</td>");
out.print("</tr>");
int i=0;
String no="";
 while(rs.next()){
 no=rs.getString("number");
 out.print("<tr>");
out.print("<td height=25>"+no+"</td>");
out.print("<td height=25>"+rs.getString(4)+"</td>");
out.print("<td height=25>"+rs.getString(1)+"</td>");
out.print("<td height=25>"+rs.getString(8)+"</td>");
out.print("<td height=25>");
out.print("<a href=teacher_find_2.jsp?number="+no+">详细信息</a>");
out.print("</td>");
out.print("</tr>");
i++;
if(i>=countPageRecord) break;
}
out.print("<tr><td colspan=8 align=center>");
out.print("共"+countRecord+"条记录,共"+countPage+"页,当前第"+dipage+"页，每页"+countPageRecord+"条记录,");
if(dipage==1);//首页
else//当前不是首页
{
out.print("<a href=teacher_find_fy.jsp?id=1>首页</a>,");
out.print("<a href=teacher_find_fy.jsp?id="+(dipage-1)+">上一页</a>,");
}
if(dipage==countPage);//是末页
else
{
out.print("<a href=teacher_find_fy.jsp?id="+(dipage+1)+">下一页</a>,");
out.print("<a href=teacher_find_fy.jsp?id="+countPage+">末页</a>,");
}

Answer 4

if(countRecord/countPageRecord==0)这里改一下“/”，用“%”

Answer 5

xfu_zq707　说的对．那是一个错误但是不是关键错误！

Answer 6

if(rs.next()==false)
{
out.print("没有符合条件的");
out.print(sql);
}else{ 
rs.beforeFirst();
这里错了 rs.beforeFirst()是把指针再移到第一行  你把指针再移到第一行干什么？ 这样当然出现空指针异常了   把上面整段去掉就可以了还有
if(countRecord/countPageRecord==0)
   countPage=countRecord/countPageRecord;
else
countPage=countRecord/countPageRecord+1;
可以改成  countPage=(countRecord+countPageRecord-1)/countPageRecord;
这样更简洁点

Answer 7

问题补充：
完成代码：
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %><%!
public String codeToString(String str)
{//处理中文字符串的函数。
String s=str;
try
{
byte tempB[]=s.getBytes("ISO-8859-1");
s=new String(tempB);
return s;
}
catch(Exception e)
{
return s;
}
}
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
</head><body>
<form id="form1" name="form1" method="post" action="Untitled-1.jsp">
  <label>
  <input type="text" name="textfield" />
  <input type="submit" name="Submit" value="提交" />
  </label>
</form>
<p>&nbsp;</p>
<p>
  <%
try{
  Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}
catch(ClassNotFoundException e){
  out.print(e);
}
try{
  String url = "jdbc:odbc:bx";
  Connection conn = DriverManager.getConnection(url,"","");
 %>
  <%
Statement stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
       String s=codeToString(request.getParameter("textfield"));
   String sql="select * from student_info where name like'%"+s.trim()+"%'";
   ResultSet rs = stmt.executeQuery(sql);
  
   int countRecord=0;//纪录条数
   int countPageRecord=0;  //每页记录数
   int countPage=0;//总页数
   countPageRecord=15;//设置每页记录数
   rs.last();
   countRecord=rs.getRow();
   if(countRecord%countPageRecord==0)
   countPage=countRecord/countPageRecord;
else
countPage=countRecord/countPageRecord+1;
  String receive_page=request.getParameter("id");
  
    int dipage=1;//当前页码数默认为1
    if(receive_page==null)
        {
          dipage=1;
        }
    else
        {
          dipage=Integer.parseInt(receive_page);
  if(dipage<=0)
  dipage=1;
 
        }
if(dipage>countPage)
{
dipage=countPage;
}
if((dipage-1)*countPageRecord==0)
rs.beforeFirst();
else
rs.absolute((dipage-1)*countPageRecord+1);
  
/*if(rs.next()==false)
{
out.print("没有符合条件的");
out.print(sql);
}else{ */
out.print("<table width=96% border=1 align=center cellpadding=0 cellspacing=0 bordercolorlight=#215594 bordercolordark=#FFFFFF>");
out.print("<tr>");
out.print("<td width=18% height=25 background=images/BG2.gif>学号</td>");
out.print("<td width=15% height=25 background=images/BG2.gif>姓名</td>");
out.print("<td width=35% height=25 background=images/BG2.gif>学院</td>");
out.print("<td width=12% height=25 background=images/BG2.gif>是否投保</td>");
out.print("<td width=20% height=25 background=images/BG2.gif>查看</td>");
out.print("<td>"+dipage+"</td>");
out.print("</tr>");
int i=0;
String no="";
 while(rs.next()){
 no=rs.getString("number");
 out.print("<tr>");
out.print("<td height=25>"+no+"</td>");
out.print("<td height=25>"+rs.getString(4)+"</td>");
out.print("<td height=25>"+rs.getString(1)+"</td>");
out.print("<td height=25>"+rs.getString(8)+"</td>");
out.print("<td height=25>");
out.print("<a href=teacher_find_2.jsp?number="+no+">详细信息</a>");
out.print("</td>");
out.print("</tr>");
i++;
if(i>=countPageRecord) break;
}
out.print("<tr><td colspan=8 align=center>");
out.print("共"+countRecord+"条记录,共"+countPage+"页,当前第"+dipage+"页，每页"+countPageRecord+"条记录,");
if(dipage==1);//首页
else//当前不是首页
{
out.print("<a href=Untitled-1.jsp?id=1>首页</a>");
out.print("<a href=Untitled-1.jsp?id="+(dipage-1)+">上一页</a>");
}
if(dipage==countPage);//是末页
else
{
out.print("<a href=Untitled-1.jsp?id="+(dipage+1)+">下一页</a>");
out.print("<a href=Untitled-1.jsp?id="+countPage+">末页</a>");
} out.print("</td></tr>");
out.print("</table>");

%>
  <%
 
    
          
          conn.close();
  }
catch(Exception ex){
  out.print(ex);                                                                                                                                                                                                                              
}
    
 %>
</p>
</body>
</html>
当我点击下一页时错误提示：java.lang.NullPointerException 

Answer 8

out.print("<a href=Untitled-1.jsp?id=1>首页</a>");
out.print("<a href=Untitled-1.jsp?id="+(dipage-1)+">上一页</a>");
}
if(dipage==countPage);//是末页
else
{
out.print("<a href=Untitled-1.jsp?id="+(dipage+1)+">下一页</a>");
out.print("<a href=Untitled-1.jsp?id="+countPage+">末页</a>");
把id改为dipage

Answer 9

呵呵，这个问题可能第一次查询条件提交到处理页面了，但执行翻页的时候查询条件值就没有了，所以查询报错
out.print("<a href=Untitled-1.jsp?id="+(dipage+1)+"&&textfield=<%=s%>>下一页</a>");
out.print("<a href=Untitled-1.jsp?id="+countPage+"textfield=<%=s%>>末页</a>");
所有的翻页都改成这样，应该就没问题了

Answer 10

问题解决了！错误原因正象sunnianfu所说的那样！在此谢谢各位了哦！