jquery+ajax乱码问题

1,修改js代码：
var url = "validatename.action";
  var m_username=encodeURIComponent($("#username").attr("value"));
  var params  =  {username:m_username};   jQuery.post(url, params, callbackFun, "json");

2.修改validatename.action，转换通过ajax传过去的username的编码
this.username = java.net.URLDecoder.decode(username,"UTF-8");