空指针问题``高手快来``

这个程序那里有问题吗?<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.sql.*"%>
<%@ page import="javax.sql.*"%>
<%@ page import="javax.naming.*"%>
<html>
<head><title>jsp登录页面</title></head>
<body>
<center>
<%
    request.setCharacterEncoding("gb2312");
    String name=request.getParameter("name");
String password=request.getParameter("password");
Connection conn=null;
Statement stmt=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
String sql=null;
%><%
        sql=" select * from zhuce where name=?";
Context ctx =new InitialContext();
DataSource ds=(DataSource)ctx.lookup("java:comp/env/jdbc/luntan");
conn=ds.getConnection();
        rs=stmt.executeQuery(sql);
if(!rs.next())
        {
  try{
  pstmt=conn.prepareStatement("insert into zhuce(name,password)values(?,?)"); 
  pstmt.setString(1,name);
  pstmt.setString(2,password);
  pstmt.executeQuery();
  out.println(name);
  out.println(password);
  }
  catch(Exception e)
  {e.printStackTrace();}
%>
             <jsp:forward page="success.jsp"/>
<%
    rs.close();
pstmt.close();
        conn.close();
}
else
{
%>
       <jspj:forward page="failure.jsp"/>
<%
    }
%></center>
</body>
</html>
<%@ page contentType="text/html;charset=gb2312"%>
<html>
<head>
<title>注册页面</title>
</head>
<body>
<center>
<h1>注册页面</h1><br>
<hr>
<br>
<br>
<br>
<form action="judge.jsp" method="post">
<table>
<tr>
<td>用户名:</td>
<td><input type="text" name="name"/></td>
</tr>
<tr>
<td>密&nbsp;&nbsp码</td>
<td><input type="password" name="password"/></td>
</tr><tr>
<td><input type="submit" value="注册"/></td>
<td><input type="reset" value="重置"/></td>
</tr>
</table>
</form>
<center>
</body>
</html>

解决方案 »

  1.   

    sql=" select * from zhuce where name=?";
    rs=stmt.executeQuery(sql);用pstmt阿 你的sql里面有? 需要pstmt.setString();
    MVC吧 大哥 眼快瞎了
      

  2.   

    conn=ds.getConnection();
            rs=stmt.executeQuery(sql);
    这里错误；而且你用的是带参数的sql语句，应该使用PreparedStatement类阿
    PreparedStatement pstmt = null;
    conn=ds.getConnection();
    pstmt = conn.prepareStatement( sql);
    rs = pstmt.executeQuery();