jsp 检测密码两次输入是否相同
我的文件不能判断,点击提交后不判断直接修改数据库 
 文件是一个修改密码的操作 
 大家帮忙看下输入不合法为什么没有弹窗 
  <%@   page   pageEncoding= "GBK "%>  
  <%@   page   import= "java.sql.* "   %>  
  <html>  
  <head>  
  <meta   http-equiv= "Content-Type "   content= "text/html;   charset=gb2312 ">  
  <title> 修改密码    </title>  
  <script   language= "JavaScript ">  
 function   OnFocus(){ 
 document.change.user.focus(); 
 } 
 function   isValid(){ 
 conForm=true; 
 if(document.change.user.value.length==0){ 
 conForm=false; 
 window.alert( '必须输入帐号才能完成登陆! '); 
 document.change.elements(0).focus();   
 } 
 else   if(document.change.pwd1.value.length==0){ 
 conForm=false; 
 window.alert( '必须输入原密码 '); 
 doucument.change.elements(1).focus();   
 } 
 else   if(document.change.pwd2.value.length==0){ 
 conForm=false; 
 window.alert( '必须输入现在的密码 '); 
 doucument.change.elements(2).focus();   
 } 
 else   if(document.change.pw2.value!=document.change.pw3.value){ 
 conForm=false; 
 pw3.value= " "; 
 window.alert( '两次输入的密码不一样 '); 
 doucument.change.elements(3).focus();   
 } 
 return   conForm;      
 } 
  </script>  
  </head>                        
  <body      onLoad= "OnFocus() "   bgcolor= "#0099FF "   background= "tj1.jpg ">    
  <p>   </p>  
  <p>   </p>  
  <p>   </p>  
  <p>   </p>  
  <form   name= "change "   method= "post "   action= "changekeyword.jsp "   onSubmit= "return   isValid() ">  
        <p   align= "center "> 帐    户:    
              <input   type= "text "   name= "user ">  
  </p>  
        <p   align= "center "> 原始密码:    <input   type= "password "   name= "pwd1 ">  
        </p>  
           <p   align= "center "> 密    码:    
           <input   type= "password "   name= "pwd2 ">  
           </p>  
           <p   align= "center "> 确认密码:    
           <input   type= "password "   name= "pwd3 ">  
           </p>  
           <p   align= "center ">  <input   type= "submit "   name= "ok "   value= "提交 "   >  
              
           <input   type= "reset "   name= "reset "   value= "重置 ">  
           </p>  
  </form>  
  </body>  
  </html>  
------解决方案-------------------- <html>  
  <head>  
  <meta http-equiv= "Content-Type " content= "text/html; charset=gb2312 ">  
  <title> 修改密码  </title>  
  <script language= "JavaScript ">    
 function isValid(){