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ajax对表单验证

2013-01-02 10:59 288 查看 
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 block
e.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 block
out.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 {

}

}
//以下是ajax部分var xmlhttp;function ajaxfun(){if (window.XMLHttpRequest){// code for IE7+, Firefox, Chrome, Opera, Safarixmlhttp=new XMLHttpRequest();}else{// code for IE6, IE5xmlhttp=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;}}
//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>

                                            

                                        

                        
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