jsp页面传递类对象的方法？

Question

如图，在servlet里面对Admin对象实例化，然后用request将数据传到前端jsp页面当中，可是admin里面数据在jsp页面中一直为空，是我的步骤错了吗？用了两种方法都没效果，一种是传admin的实例化参数，另外一种是传admin对象

request.setCharacterEncoding("UTF-8");
AdminDao ad = new AdminDao();
String pathInfo = request.getPathInfo();
pathInfo = (pathInfo == null ? "/" : pathInfo);
switch (pathInfo) {
case "/adminUpdate":
Admin adm = null;
try {
adm = ad.getAdminById(111);
request.setAttribute("id", Integer.valueOf(adm.getAdmin_id()).toString());
request.setAttribute("name", adm.getAdmin_name());
request.setAttribute("pwd", adm.getAdmin_password());
request.setAttribute("tel", adm.getAdmin_tel());
request.setAttribute("sex", adm.getAdmin_sex());
request.setAttribute("adm", adm);
} catch (SQLException e) {
e.printStackTrace();
}
response.sendRedirect(request.getContextPath() + "/admin/adminmaning");
break;

        <%
    Admin admin = (Admin) request.getAttribute("admin");
%>
<c:if test="${id==0}">
    <h4>没有任何资料</h4>
</c:if>
<form action="admin/adminUpdate" method="get">
    <c:if test="${id!=0}">
        <table border="1">
            <tr>
                <td>姓名</td>
                <td><input type="text" name="adminName" value="${name}">
                </td>
            </tr>
            <tr>
                <td>密码</td>
                <td><input type="text" name="adminPwd" value="${pwd}"></td>
            </tr>
            <tr>
                <td>性别</td>
                <td><input type="text" name="adminSex"
                    value="${sex}"></td>
            </tr>
            <tr>
                <td>联系方式</td>
                <td><input type="text" name="adminTel"
                    value="${tel}"></td>
            </tr>
            <tr>
                <td><button type="submit">提交</button></td>
                <td><button type="reset">取消</button></td>
            </tr>
        </table>
    </c:if>
</form>

Answer 1

request域作用范围是一次请求响应,你这里使用了重定向,重定向是两次请求两次响应,所以获取不到request域中的值,试试将response.sendRediect换成request.getRequestDispatcher(path).foward()