js,ajax验证编号是否存在，input只能输入数字,form表单验证

ajax验证编号是否存在

前台：

<input type="text"  id="add_lid"  onchange="checklid();"   />

<script language=javascript>

function checklid() {    
var lidVal = document.getElementById("add_lid").value;
//alert(usernameVal);
var url = "<%=path%>/defect/lineDefectAction!validlid";
$.post(url,{lid:lidVal},function(result){

if(result == 0){
alert('您输入的线路编号不存在，请重新输入！');
document.getElementById("lid").value="";
}
});
}

</script>

后台：

public void validlid() throws Exception{
    HttpServletRequest request= ServletActionContext.getRequest();
    request.setCharacterEncoding("utf-8");
    HttpServletResponse response = ServletActionContext.getResponse();
    response.setContentType("text/html;charset=utf-8");
    String flag;
    String lid = request.getParameter("lid");
    LineInfo info = lineInfoService.getLineInfo(lid);
    if(info.getName()==null||info.getName().equals(""))
    flag = "0";
    else flag = "1";
    try {
PrintWriter pw = response.getWriter();
pw.write(flag);
pw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}


}

form表单验证

  <form action="Action!add" method="post"  onsubmit="return VaildlineDefectadd()">

 <input type="text"  id="add_lid"  onchange="checklid();"   />

</form>

<script language=javascript>

function VaildlineDefectadd() {    
var lidVal = document.getElementById("add_lid").value;
if(lidVal=="")
     {
     alert("不能为空！");
     return false;
  }

} 

</script>

input只能输入数字

<script language=javascript>
function keyPress()
{

 //46是delete,8是backspace(退格键),37是左箭头，39是右箭头;方法的功能是除开前面的几个按键和数字，其他的按键都返回false,即按了不起作用
 if(!(event.keyCode==46)&&!(event.keyCode==8)&&!(event.keyCode==37)&&!(event.keyCode==39))
  if(!((event.keyCode>=48&&event.keyCode<=57)||(event.keyCode>=96&&event.keyCode<=105)))
    event.returnValue=false;
}
</script>

<input  onkeydown="keyPress();">

下面附上keycode对照表