| 本文实例为大家分享了AJAX实现注册验证用户名的具体代码，供大家参考，具体内容如下 功能说明 当用户在注册页面输入用户名并且鼠标焦点离开输入框时，到数据表中去验证该用户名是否已经存在，如果存在提示不可用，否则，提示可用。 接口 public interface UserDao { public User findName(String name);}接口实现类 import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class UserDaoImpl implements UserDao { @Override public User findName(String name) { User user =null; Connection conn = DBHelper.getConn(); String sql = "select * from user where name=?"; try { PreparedStatement ps = conn.prepareStatement(sql); ps.setString(1,name); ResultSet rs = ps.executeQuery(); if (rs.next()){ user = new User(); user.setId(rs.getInt(1)); user.setName(rs.getString(2)); user.setPassword(rs.getString(3)); } } catch (SQLException e) { e.printStackTrace(); } return user; }}servlet import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet("/findName")public class FindNameServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); String name = request.getParameter("name"); UserDao userDao = new UserDaoImpl(); User name1 = userDao.findName(name); if (name1!=null){ response.getWriter().write("1"); }else { response.getWriter().write("2"); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); }}JSP页面 <%@ page contentType="text/html;charset=UTF-8" language="java" %><html> <head> <title>AJAX实际操作注册验证用户名</title> <script src="js/jquery-1.8.3.js"></script> </head> <body> <form action="#" method="post"> <script type="text/javascript"> $(function () { $("[name=userName]").blur(function () { $.ajax({ type:"get", url:"findName?name="+$("[name=userName]").val(), dataType:"text", success:function (data) { //alert(data); if (data=="1"){ $("#show").html("用户已存在！！！") }else { $("#show").html("用户名可用") } } }) }) }); </script> 账号<input type="text" name="userName"><span id="show"></span></br> 密码<input type="password" name="password"></br> <input type="submit" value="提交"> </form> </body></html>数据库如下： 
运行结果如下： 
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持51zixue.net。
下载地址:
Ajax实现局部刷新的方法实例
Ajax实现省市县三级联动 |
