一个小问题我的积分不多帮忙

我是新手感谢CSDN的朋友帮我解决了很多问题呵呵现在是这样的页面注册用户的时候我用ajax验证用户名是否存在成功了该用户的用户名在数据库已存在已经提示他“用户名已被占用”现在我需要提交表单当用户点击提交表单的时候如果我用JS 清空文本框这样不好那我要怎么做才能再一次的提醒他 “用户名已被占用” 并保留他原来的的注册的帐号并且阻止他提交表单

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onclick 上 onsubmit =（return false）
我数据库是 SQL2000的测试表是 TB_USER
字段就一个 username
记录2条
admin
zhuchao测试页面2个regist.jsp
Java code
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
      <script type="text/javascript">
          function to(){
              var name=document.getElementById("username").value;
              var url="dbop.jsp?username="+encodeURI(encodeURI(name)); //处理中文
             var xmlHttpRequest=new ActiveXObject("microsoft.xmlhttp");
                    xmlHttpRequest.open("post",url,true);
                    xmlHttpRequest.send(null);
                    xmlHttpRequest.onreadystatechange=function(){
                        if(xmlHttpRequest.readystate==4 && xmlHttpRequest.status==200){
                            ajax.innerHTML = xmlHttpRequest.responseText;
                        }
                    }
          }
      </script>
  </head>
  <body><div id="ajax"></div>
    <form name="name1">
        请输入注册ID：<input id="username" type="text" name="username" value=""/><br>
        <input type="button" value="注册" onclick="to()">
    </form>
  </body>
</html>
dbop.jspJava code<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>
<%@page import="java.net.URLDecoder"%>
<%@page import="java.sql.*"%>
<%
    String name = URLDecoder.decode(request.getParameter("username"),"utf-8");//处理中文
    Connection conn=null;
    Statement statement = null;
    ResultSet rs=null;
    try{
        Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
        conn = DriverManager.getConnection("jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=test","sa", "sa");
        statement=conn.createStatement();
        rs=statement.executeQuery("select username from tb_user where username = '"+name+"'");
        if(rs.next()){
            out.print("此ID已存在！");
        }else{
            out.println("此ID可注册！");
        }
    }catch(Exception exception){
        exception.printStackTrace();
    }finally{
        rs.close();
        statement.close();
        conn.close();

    }
%>第一个页面你输入好点击注册不刷新页面会有提示信息。
你不喜欢提交这个事件可以选别的，只要你喜欢。
form的onsubmit里加处理<script>
function checkSubmit(){
  //判断用户名是否被占用，如果被占用就像以下处理
  alert("用户名被占用");
  return false;
}
</script>
<form onsubmit="return checkSubmit()">
  <input type="submit" value="提交"/>
</form>
<script>
function checkSubmit(){
  //判断用户名是否被占用，如果被占用就像以下处理
  alert("用户名被占用");
  return false;
}
</script>
<form onsubmit="return checkSubmit()">
  <input type="submit" value="提交"/>
</form>
幸亏大家了   问题解决了
附上代码：
页面：<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>AJAX</title> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">  </head>
<script type="text/javascript">
var xmlHttpRequest;
var str = null;
function createXMLHttpRequest() {
if (window.ActiveXObject) {
xmlHttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
} else if (window.XMLHttpRequest) {
xmlHttpRequest = new XMLHttpRequest();
}
}
function yzName(name) {
var userInfo = document.getElementById('userName2').value;
if (userInfo == "") {
var str = "<font color=red>帐号不能为空</font>";
document.getElementById('rest').innerHTML = str;
return false;
}
createXMLHttpRequest();
xmlHttpRequest.onreadystatechange = assignCallBack;
var url = "ajaxText.action?userName3=" + name;
xmlHttpRequest.open("post", url, true);
xmlHttpRequest.setRequestHeader("Content-Type",
"application/x-www-form-urlencoded");
xmlHttpRequest.send(null);
}
function assignCallBack() { if (xmlHttpRequest.readyState == 4 && xmlHttpRequest.status == 200) {
str = xmlHttpRequest.responseText;
document.getElementById('rest').innerHTML = str;
}
} function checkForm() {
var regu = "^(<font color=red>X</font> <font color=red>该帐号已被注册</font>)";
var abc = str;
var re = new RegExp(regu);
if (abc.search(re) != -1) {
alert('请重新写帐号');
document.getElementById('userName2').focus();
} else {
myForm.submit();
}
}
</script> <body>
<form action="index.jsp" name="myForm">
<table>
<tr>
<td>
<input type="text" name="userName2" id="userName2"
onblur="yzName(this.value)">
</td>
<td>
<div id="rest"></div>
</td>
</tr>
<tr>
<td>
</td>
<td>
<input type="button" onclick=checkForm(); value="注册">
</td>
</tr>
</table>
</form> </body>
</html>
ACTION类： public String ajaxText() throws Exception{
response.setContentType("text/html;charset=UTF-8");
request.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
String name = request.getParameter("userName3");
User a =  userService.findUserByName(name);
System.out.println("----------------------   "+a);
if(a != null){
String str = "<font color=red>X</font> <font color=red>该帐号已被注册</font>";
out.println(str);
}else{
String str = "<img src='images/accept.png' />";
session.put("str", str);

out.println(str);
}

out.close();
return null;
}

一个小问题 我的积分不多帮忙

解决方案 »

一个小问题我的积分不多帮忙