ajax表单验证后台用户名是否存在

来源：互联网发布：iphone电脑同步软件编辑：程序博客网时间：2024/05/18 22:40

package ajaxservlet;import java.io.IOException;import java.io.PrintWriter;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import db.DBconnection;public class AjaxServlet extends HttpServlet {//private static final long serialVersionUID = 1L;public void destroy() {try {DBconnection.connectionClose();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");response.setHeader("Cache-Control","no-cache");PrintWriter out=response.getWriter();String name=request.getParameter("username");String pass=request.getParameter("userpass");String pass2=request.getParameter("userpass2");String a=request.getParameter("a");String b=request.getParameter("b");System.out.println(name+" "+pass);System.out.println("a "+a);System.out.println("b "+b);request.setAttribute("name",name);System.out.println(name);try {if(checkName(name)){System.out.println(checkName(name));System.out.println("checkname="+name);out.write("用户名已经存在，请重新输入!");System.out.println("xxxxxxxxxxxxxxxxx");request.setAttribute("error.message","用户名已经存在");}else{out.write("此用户名合法");}} catch (SQLException e) {// TODO Auto-generated catch blockout.close();e.printStackTrace();}}public boolean checkName(String name) throws SQLException   //检查用户名是否存在{boolean flag=false;Connection conn=DBconnection.getConnection();System.out.println("conn="+conn);/*String sql="select * from a_user where username='"+name+"'";System.out.println("name="+name);Statement state=conn.createStatement();ResultSet rs=state.executeQuery(sql);*/String sql="select * from a_user where username=?";PreparedStatement pstate=conn.prepareStatement(sql);pstate.setString(1,name);ResultSet rs=pstate.executeQuery();//System.out.println(rs.getInt(0));//System.out.println(rs.getString("username"));while(rs.next()){System.out.println("rs.getString(username)="+rs.getString("username"));flag=true;}return flag;}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//response.setContentType("text/html");this.doGet(request, response);}public void init() throws ServletException {}}

[html] view plaincopyprint?

//以下是ajax部分
var xmlhttp;
function ajaxfun()
{
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
return xmlhttp;
}
window.onload=function()
{
document.getElementById("username1").onblur=function()
{
var name=document.getElementsByName("username")[0].value;
xmlhttp=ajaxfun();
xmlhttp.onreadystatechange=check;
//xmlhttp.open("get","http://localhost:8080/ajaxtest/AjaxServlet?username="+name+"&time="+new Date().toTimeString(),true);
//以下是get方法传值
/*xmlhttp.open("get","./AjaxServlet?username="+name+"&time="+new Date().toTimeString(),true);
xmlhttp.send(null);*/
/*
* 如果需要像 HTML 表单那样使用 POST 传递数据，请使用 setRequestHeader() 来添加 HTTP 头。
* 然后在 send() 方法中规定您希望发送的数据：
*/
xmlhttp.open("post","./AjaxServlet?username="+name+"&time="+new Date().toTimeString(),true);
xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded")
xmlhttp.send("a=100&b=222");
}
}
function check()
{
alert(xmlhttp.status);
if(xmlhttp.readyState==4 && xmlhttp.status==200)
{
alert(xmlhttp.status);
document.getElementById("span").innerHTML=xmlhttp.responseText;
}
}

//以下是ajax部分var xmlhttp;function ajaxfun(){if (window.XMLHttpRequest)  {// code for IE7+, Firefox, Chrome, Opera, Safari  xmlhttp=new XMLHttpRequest();  }else  {// code for IE6, IE5  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");  }return xmlhttp;}window.onload=function(){document.getElementById("username1").onblur=function(){var name=document.getElementsByName("username")[0].value;xmlhttp=ajaxfun();xmlhttp.onreadystatechange=check;//xmlhttp.open("get","http://localhost:8080/ajaxtest/AjaxServlet?username="+name+"&time="+new Date().toTimeString(),true);//以下是get方法传值/*xmlhttp.open("get","./AjaxServlet?username="+name+"&time="+new Date().toTimeString(),true);xmlhttp.send(null);*//* * 如果需要像 HTML 表单那样使用 POST 传递数据，请使用 setRequestHeader() 来添加 HTTP 头。 * 然后在 send() 方法中规定您希望发送的数据： */xmlhttp.open("post","./AjaxServlet?username="+name+"&time="+new Date().toTimeString(),true);xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded")xmlhttp.send("a=100&b=222");}}function check(){alert(xmlhttp.status);if(xmlhttp.readyState==4 && xmlhttp.status==200){alert(xmlhttp.status);document.getElementById("span").innerHTML=xmlhttp.responseText;}}

[html] view plaincopyprint?

//jsp中的body部分
<body>
<%--<form action="/ajaxtest/RegisteServlet" method="get">
<form action="" method="get" enctype="application/x-www-form-urlencoded">
--%>
<form action="/ajaxtest/RegisteServlet" method="get">
用户名:<input type="text" name="username" id="username1"/><span id="span"></span><br>
密码:<input type="password" name="userpass"/><br>
确认密码:<input type="password" name="userpass2"/><br>
<input type="submit" value="提交"/>
<input type="button" name="username" id="username1" value="点击"/>
</form>
</body>