var url = "login?userName=" + encodeURI(encodeURI($("#userName").val()));
    url = convertURL(url);
    $.get(url,null,function(data){
    
     alert(decodeURI(data));
        $("#result").html("<font color=red>"+decodeURI(decodeURI(data))+"</font>");
});
PrintWriter out=response.getWriter();
response.setContentType("text/html;charset=utf-8");
out.print("用户名不存在");我都设为utf-8了  还是 返回????