javascript实现用户名是否存在的实时提醒

来源：互联网发布：大数据宣传片编辑：程序博客网时间：2024/06/06 01:18

1.register.jsp中用户名处要这样写：

<tr>  <td>用户名:</td>  <td>    <input type="text" name="username" size="25" maxlength="25" id="userid" onblur="validate()">    <div id="usermsg"></div>  </td></tr>

2.在register.jsp的HTML标签<head></head>内写javascript：

<script type="text/javascript">var req;function validate() {var idField = document.getElementById("userid");var url = "validate.jsp?id=" + escape(idField.value);//alert(url);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) {//alert(req.responseText);var msg = req.responseXML.getElementsByTagName("msg")[0];//alert(msg);        setMsg(msg.childNodes[0].nodeValue);}}}function setMsg(msg) {//alert(msg);mdiv = document.getElementById("usermsg");if(msg == "invalid") {mdiv.innerHTML = "<font color='red'>username exists</font>";} else {mdiv.innerHTML = "<font color='green'>congratulations! you can use this username!</font>";}}</script>

3.创建validate.jsp页面，写校验username是否在数据库中存在的判断：

    <%@page import="com.shopping.User"%><%response.setContentType("text/xml");response.setHeader("Cache-Control", "no-store"); //HTTP1.1response.setHeader("Pragma", "no-cache"); //HTTP1.0response.setDateHeader("Expires", 0); //prevents catching at proxy server//System.out.println(request.getParameter("id"));String username = request.getParameter("id");//System.out.println(username);boolean userExist = User.isUserExist(username);//System.out.println(userExist);if(userExist){//check the databaseresponse.getWriter().write("<msg>invalid</msg>");} else {response.getWriter().write("<msg>valid</msg>");}%>

4. 第3步中的User.isUserExist(username)是链接数据库查询的java文件，是类User中的一个方法，具体如下：

public static boolean isUserExist(String username){boolean userExist = false;Connection conn = null;Statement stmt = null;ResultSet rs = null;try {conn = DB.getConn();stmt = DB.createStmt(conn);String sql = "select * from user where username = '" + username + "'";rs = DB.executeQuery(stmt, sql);if(rs.next()){userExist = true;return userExist;} else {return userExist;}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally {// TODO: handle finally clauseDB.close(rs);DB.close(stmt);DB.close(conn);}return userExist;}/// end

另，附上判断用户名和密码复杂程度的文件regcheckdata.js。

function checkdata() {var ssn=form.username.value.toLowerCase();if (!checkUserName(ssn)) return false;  //用户名检查if( strlen(form.password.value)<6 || strlen(form.password.value)>16 ) {alert("\正确地登录密码长度为6-16位，仅可用英文、数字、特殊字符！")form.password.focus()return false;}if( strlen2(form.password.value) ) {alert("\您的密码中包含了非法字符，仅可用英文、数字、特殊字符！")form.password.focus()return false;}if( form.password.value == form.username.value ) {alert("\用户名和密码不能相同！")form.password.focus()return false;}if( form.password2.value =="" ) {alert("\请输入密码确认！")form.pwd2.focus()return false;}if( form.password2.value != form.password.value ) {alert("\两次密码输入不一致！")form.password.focus()return false;}//检查电话if( form.phone.value =="" ) {alert("\请输入电话！")form.phone.focus()return false;}//检查地址if( form.addr.value =="" ) {alert("\请输入送货地址！");form.addr.focus();return false;}return true;}function checkUserName(ssn){if( ssn.length<3 || ssn.length>18 ) {alert("\请输入正确的用户名,用户名长度为3-18位！")form.username.focus()return false;}if (isWhiteWpace(ssn)){alert("\请输入正确的用户名,用户名中不能包含空格！")form.username.focus()return false;}if (!isSsnString(ssn)){alert("\    对不起，您选择的用户名不正确或已被占用！用户名\n由a～z的英文字母(不区分大小写)、0～9的数字、点、减\n号或下划线组成，长度为3～18个字符，只能以数字或字母\n开头和结尾,例如:kyzy_001。")form.username.focus()return false;}return true;}function strlen(str){var len;var i;len = 0;for (i=0;i<str.length;i++){if (str.charCodeAt(i)>255) len+=2; else len++;}return len;}function strlen2(str){var len;var i;len = 0;for (i=0;i<str.length;i++){if (str.charCodeAt(i)>255) return true;}return false;}function isWhiteWpace (s){var whitespace = " \t\n\r";var i;for (i = 0; i < s.length; i++){   var c = s.charAt(i);if (whitespace.indexOf(c) >= 0) {  return true;}}return false;}function isSsnString (ssn){var re=/^[0-9a-z][\w-.]*[0-9a-z]$/i;if(re.test(ssn))return true;elsereturn false;}function checkssn(gotoURL) {   var ssn=form.username.value.toLowerCase();   if (checkUserName(ssn)){   var open_url = gotoURL + "?username=" + ssn;   window.open(open_url,'','status=0,directories=0,resizable=0,toolbar=0,location=0,scrollbars=0,width=322,height=200');}}

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