request.setAttribute无法传值的菜鸟问题

Question

Serlvet中有如下代码:
// 添加成功,跳回到添加页面
requestDispather = request.getRequestDispatcher("/add.jsp");
request.setAttribute("actionMsg", "添加成功");
requestDispather.forward(request, response);
return;add.jsp中有如下代码:
<input type="hidden" name="actionMsg" value='<%=request.getParameter("actionMsg")%>'>添加成功,回到添加页面后,怎么就拿不到actionMsg呢?其他值都能拿到.晕了...

Answer 1

附值用set,取值用request.getAttribute("actionMsg")

Answer 2

应该修改如下
// 添加成功,跳回到添加页面
requestDispather = request.getRequestDispatcher("/add.jsp");
request.setAttribute("actionMsg", "添加成功");
requestDispather.forward(request, response);
return;add.jsp中有如下代码:
<input type="hidden" name="actionMsg" value='<%=request.getAttribute("actionMsg")%>'>

Answer 3

// 或者这样
requestDispather = request.getRequestDispatcher("/add.jsp?actionMsg='添加成功'");
requestDispather.forward(request, response);
return;add.jsp中有如下代码:
<input type="hidden" name="actionMsg" value='<%=request.getAttribute("actionMsg")%>'>

Answer 4

你用setAttribute当然对应的JSP里面 要用getAttribute