AJAX用于判定用户是否注册
程序员文章站
2022-04-20 13:34:58
在很多注册的页面上，我们可能会遇到以下情况，当我们注册用户名的时候可能会提示该用户名已注册，其实现是应用ajax技术。
首先写一个登陆页面
在很多注册的页面上，我们可能会遇到以下情况，当我们注册用户名的时候可能会提示该用户名已注册，其实现是应用ajax技术。
首先写一个登陆页面
<html>
<head>
<title></title>
<script type="text/javascript">
var xmlhttp;
var flag;
function createxmlhttp(){
if(window.xmlhttprequest){
xmlhttp=new xmlhttprequest();
}else{
xmlhttp=new activexobject("microsoft.xmlhttp");
}
}
function checkuserid(userid){
createxmlhttp();
xmlhttp.open("post","checkservlet?userid="+userid);
xmlhttp.onreadystatechange=checkuseridcallback;
xmlhttp.send();
document.getelementbyid("msg").innerhtml="正在验证。。。";
}
function checkuseridcallback(){
if(xmlhttp.readystate==400){
if(xmlhttp.status==200){
var text=xmlhttp.responsetext;
if(text=="true"){
flag=false;
document.getelementbyid("msg").innerhtml="用户id重复，无法使用";
}else{
flag=true;
document.getelementbyid("msg").innerhtml="此用户id可以注册";
}
}
}
}
function checkform(){
return flag;
}
</script>
</head>
<body>
<form action="tt.jsp" method="post" onsubmit="return checkform()">
用户id <input type="text" name="userid" onblur="checkuserid(this.value)"><span id="msg"></span><br>
姓名：<input type="text" name="name"><br>
密码：<input type="password" name="password"><br>
<input type="button" value="注册">
<input type="reset" value="重置">
</form>
</body>
</html>
随后写一个servlet的java代码
import java.io.ioexception;
import java.io.printwriter;
import java.sql.connection;
import java.sql.drivermanager;
import java.sql.preparedstatement;
import java.sql.resultset;
import java.sql.sqlexception;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
public class checkservlet extends httpservlet{
public static final string dbdriver = "oracle.jdbc.oracledriver";
public static final string dburl = "jdbc:oracle:thin:@59.173.240.149:1521:heer";
public static final string dbuser = "hnsyu_dev";
public static final string dbpass = "hnsyuok";
public void doget(httpservletrequest request,httpservletresponse response)
throws servletexception,ioexception{
this.dopost(request, response);
}
public void dopost(httpservletrequest request,httpservletresponse response)
throws servletexception,ioexception{
request.setcharacterencoding("gbk");
response.setcontenttype("text/html");
connection connection = null;
preparedstatement preparedstatement = null;
resultset resultset = null;
printwriter out = response.getwriter();
string userid = request.getparameter("userid");
try {
class.forname(dbdriver);
connection = drivermanager.getconnection(dburl, dbuser, dbpass);
string sql = "select count(userid) from userdemo where userid=?";
preparedstatement = connection.preparestatement(sql);
preparedstatement.setstring(1,userid);
resultset = preparedstatement.executequery();
if (resultset.next()) {
if(resultset.getint(1)>0){
out.print("false");
system.out.println("true");
}else {
out.print("false");
}
}
out.close();
} catch (exception e) {
e.printstacktrace();
}finally{
try {
connection.close();
} catch (exception e) {
e.printstacktrace();
}
}
}
}
其中还需要在web.xml中进行配置
<?xml version="1.0" encoding="utf-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>checkservlet</servlet-name> <servlet-class>checkservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>checkservlet</servlet-name> <url-pattern>/checkservlet</url-pattern> </servlet-mapping> </web-app>
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。