Since we are not calling body tag in jsp in jsr 168 portlet so simply create a script tag and call function as :-
<script>
function checkEnter()
{
document.body.onkeypress = enterKey
}
checkEnter();
</script>
Simply add this in your jsp and in check enter function you can call your own functions as I am calling enterKey Functions,
Here I am checking for the enter key press :
<script>
function enterKey(evt) {
var evt = (evt) ? evt : event;
var charCode = (evt.which) ? evt.which : evt.keyCode;
if (charCode == 13) {
setOperationName('POST','RECEIPT');
return false;
}
return true;
}
</script>