1.首先附上我的注册页面源码。（这其中的User类没有很好的封装及分层，大家凑合着看，我会在最后贴上User的源码，中间的那段JavaScript是重中之重）：
<%...@ page language="java" import="java.util.*" pageEncoding="GB18030"%><%...@ page import="com.ycringfinger.shopping.*" %><%...
request.setCharacterEncoding("GB18030"); String action = request.getParameter("action"); if(action!=null && action.equals("register")){ String username = request.getParameter("username"); String password = request.getParameter("password"); String phone = request.getParameter("phone"); String addr = request.getParameter("addr"); User u = new User(); u.setUsername(username); u.setPassword(password); u.setPhone(phone); u.setAddr(addr); u.setRdate(new Date(System.currentTimeMillis()));
u.save();
%> <center>注册成功，谢谢</center><%... return; }%><html> <head> <title>用户注册</title> <script language=JavaScript src="script/regcheckdata.js"></script> <script type="text/javascript">... var req;
function validate() ...{ var idField = document.getElementById("username"); var url = "validate.jsp?username=" + escape(idField.value); if(window.XMLHttpRequest) ...{ req = new XMLHttpRequest(); } else if (window.ActiveXObject) ...{ req = new ActiveXObject("Microsoft.XMLHTTP");
} req.open("GET", url, true); req.onreadystatechange = callback; req.send(null); } function callback() ...{ if(req.readyState == 4) ...{ if(req.status == 200) ...{ var msg = req.responseXML.getElementsByTagName("msg")[0]; setMsg(msg.childNodes[0].nodeValue) } } } function setMsg(msg) ...{ if(msg == "valid") ...{ document.getElementById("usermsg").innerHTML = "<font color='green'>恭喜你，该用户名尚未注册</font>" } else if(msg == "invalid") ...{ document.getElementById("usermsg").innerHTML = "<font color='red'>该用户名已注册</font>" } } </script> </head> <body> <form name="form" action="register.jsp" method="post" onSubmit="return checkdata()"> <input type="hidden"name="action" value="register"> <table width="750" align="center" border="2"> <tr> <td> 用户名: </td> <td> <input type="text" name="username" size="30" maxlength="10" onblur="validate()"><div id="usermsg"></div> </td> </tr> <tr> <td> 密码: </td> <td> <input type="password" name="password" size="15" maxlength="12"> </td> </tr> <tr> <td> 密码确认: </td> <td> <input type="password" name="password2" size="15" maxlength="12"> </td> </tr> <tr> <td> 电话: </td> <td> <input type="text" name="phone" size="15" maxlength="12"> </td> </tr> <tr> <td> 地址: </td> <td> <textarea rows="12" cols="80" name="addr"></textarea> </td> </tr> <tr> <td> <input type="submit" value="提交"> <input type="reset" value="重置"> </td> </tr> </table> </form> </body></html>
2.validate.jsp的源码如下（注意前面那几个设置属性如setContentType,setHeader等是必需的）：
<%...@ page language="java" import="java.util.*" pageEncoding="GB18030"%><%...@ page import="com.ycringfinger.shopping.*" %><%... response.setContentType("text/xml"); response.setHeader("Cache-Control", "no-store"); response.s