How to validate username and password in a login screen?
1)login.jsp:
<html> <head> <script type="text/javascript"> function showData(){ var user=document.getElementById("username").value; var pass=document.getElementById("password").value; xmlHttp=GetXmlHttpObject() var url="check.jsp"; url=url+"?user="+user+"&&pass="+pass; xmlHttp.onreadystatechange=stateChanged xmlHttp.open("GET",url,true) xmlHttp.send(null) } function stateChanged(){ if(xmlHttp.readyState==4 || xmlHttp.readyState=="complete"){ var showdata = xmlHttp.responseText; document.getElementById("lab").innerHTML=showdata; document.getElementById("lab").style.color="red"; document.getElementById("username").value=" "; document.getElementById("password").value=""; } } function GetXmlHttpObject(){ var xmlHttp=null; try{ xmlHttp=new XMLHttpRequest(); } catch(e){ try{ xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); } catch(e){ xmlHttp=new ActiveXObject("Microsoft.XMLHTTP"); } } return xmlHttp; } </script> </head> <form name="form"> <table> <tr><td>Username:</td><td><input type="text" id="username"></td></tr> <tr><td>Password:</td><td><input type="password" id="password"></td></tr> <tr><td></td><td><input type="button" value="Submit" onclick="showData();"></td></tr> </table> <label id="lab"></label> </form> </html>
2)check.jsp:
<%@ page import="java.sql.*" %> <% String user = request.getParameter("user"); String pass = request.getParameter("pass"); String data =""; try{ Class.forName("com.mysql.jdbc.Driver"); Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root"); Statement st=con.createStatement(); ResultSet rs=st.executeQuery("select * from login where username='"+user+"' and password='"+pass+"'"); int count=0; while(rs.next()){ count++; } if(count>0){ %> <jsp:forward page="success.jsp"/> <% } else{ data="Username or Password is Invalid!"; } out.println(data); System.out.println(data); } catch(Exception e){ System.out.println(e); } %>
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