解决方案：在原请求也加入request.setCharacterEncoding("gb2312");

例子1：

<%

request.setCharacterEncoding("gb2312");

%>

<jsp:include page="content.jsp">

<jsp:param name="param" value="哈哈哈"></jsp:param>

</jsp:include>

例子2：

<%

request.setCharacterEncoding("gb2312");

%>

<jsp:forward page="content.jsp">

<jsp:param name="param" value="哈哈哈"></jsp:param>

</jsp:forward>