这可能是因为你在声明javascript事件时错过了引用。你可以尝试这样的吗？

It may be because you are missing the Quote while declaring the javascript event. Can you try something like this?

out.print("<button type=\"button\" onclick='javascript:return friendnamebtn(this)' id=\"btn_friends\">");

function friendnamebtn(sender)
{
     //write your code here
     return false;
}