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こんにちは、私はJSPを初めて使用します。プロジェクトのカスタマー サインアップ ページを開発しています。ユーザー ID を一意にしたいので、テキスト フィールドのonBlurイベントで検証用の ID を送信しています。しかし、null ポインターを取得しています。例外。このコードを手伝ってください。

HTML コード (register.html):

<head>

<script type="text/javascript">
function OnButton1()
{
var userid = document.getElementById("user").value;
window.location.replace("register.jsp?userid="+userid);
document.registerform.action = "useridvalidcode.jsp"

    document.registerform.submit();
    return true;
}
    function confirmPass() {
        var pass = document.getElementById("pass").value;
        var confPass = document.getElementById("c_pass").value;
        if(pass != confPass) {          
alert('Wrong confirm password !');
document.getElementById("c_pass").value="";
document.registerform.cpassword.focus();

}   }</script>
</head>

<body bgcolor="#DFBB81" onload="document.registerform.userid.focus();">
<div align="center">
  <table width="1024" border="0">
    <tr>
      <td><jsp:include page="head.jsp"/></td>
    </tr>
    <tr>
      <td height="217" valign="top">
      <form name="registerform" method="post" action="registercode.jsp">
      <table width="563" border="0">
        <tr>
          <td width="19">&nbsp;</td>
          <td width="144"><font color="#990000" size="+2">Register:</font></td>
          <td width="204">&nbsp;</td>
          <td width="168">&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>User Id: </td>
          <td><label></label></td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td><input type="text" name="userid" id="user" required="required" onblur="return OnButton1();"/></td>
          <td><label></label></td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>Password: </td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td><input type="password" id="pass" name="password" required="required" /></td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>Confirm password: </td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td><label>
         <input type="password" id="c_pass" value="" onblur="confirmPass()" name="cpassword" required="required" />
          </label></td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>Email:</td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td><label>
            <input type="email" name="email" required="required" />
          </label></td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>Mobile no: </td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>
           <input type="tel" pattern='\d{10}' title="10 digit mobile number format" required="required"  name="mobileno"/>         </td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>Address:</td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td><textarea name="address" rows="5" required="required" style="resize:none"></textarea></td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td><input type="submit" name="Submit" value="Submit" />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
            <input type="reset" name="Submit2" value="Reset" /></td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td><span class="style2">*</span> All fields mandatory </td>
          <td>&nbsp;</td>
          <td>&nbsp;</td>
        </tr>
      </table>
      </form></td>
    </tr>
    <tr>
      <td><jsp:include page="foot.html"/></td>
    </tr>
  </table>
</div>
</body>
</html>

JSP コード (useridvalidcode.jsp):

<body>
 <%@page import="java.sql.*"%>
 <%
 String userid=request.getParameter("userid");
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con = DriverManager.getConnection("jdbc:odbc:pd");
ResultSet rs = null;

Statement st = con.createStatement();
String sql=("select * from register where userid='"+ userid +"'");
st.executeQuery(sql) ;
                int ct = 0;
   while(rs.next())
      {
      ct++; 
      }
   if (ct > 0)
      {
        %><script type="text/javascript"> alert("duplicate"); </script> <%
      }
   else
      {
    %><script type="text/javascript"> alert("new"); </script> <%
      }
rs.close();
st.close();
con.close();
}
catch(Exception e){
out.println(e.toString());
                return ;

}
%>
<script language="javascript">
alert("Successfully regestered");
</script>
<jsp:include page="../page/home.jsp"/>
</body>
</html>
<body>
 <%@page import="java.sql.*"%>
 <%
 String userid=request.getParameter("userid");
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con = DriverManager.getConnection("jdbc:odbc:pd");
ResultSet rs = null;

Statement st = con.createStatement();
String sql=("select * from register where userid='"+ userid +"'");
st.executeQuery(sql) ;
                int ct = 0;
   while(rs.next())
      {
      ct++; 
      }
   if (ct > 0)
      {
        %><script type="text/javascript"> alert("duplicate"); </script> <%
      }
   else
      {
    %><script type="text/javascript"> alert("new"); </script> <%
      }
rs.close();
st.close();
con.close();
}
catch(Exception e){
out.println(e.toString());
                return ;

}
%>
<script language="javascript">
alert("Successfully regestered");
</script>
<jsp:include page="../page/home.jsp"/>
</body>
</html>

<body>
 <%@page import="java.sql.*"%>
 <%
 String userid=request.getParameter("userid");
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con = DriverManager.getConnection("jdbc:odbc:pd");
ResultSet rs = null;

Statement st = con.createStatement();
String sql=("select * from register where userid='"+ userid +"'");
st.executeQuery(sql) ;
                int ct = 0;
   while(rs.next())
      {
      ct++; 
      }
   if (ct > 0)
      {
        %><script type="text/javascript"> alert("duplicate"); </script> <%
      }
   else
      {
    %><script type="text/javascript"> alert("new"); </script> <%
      }
rs.close();
st.close();
con.close();
}
catch(Exception e){
out.println(e.toString());
                return ;

}
%>
<script language="javascript">
alert("Successfully regestered");
</script>
<jsp:include page="../page/home.jsp"/>
</body>
</html>
4

1 に答える 1

2

エラーはここから来ていると確信しています。

ResultSet rs = null;
...
while(rs.next())

ここで、rs は常に null です。

于 2012-09-27T12:10:52.933 に答える