怎么用Java进行输入查找

Question

我设置了一个查找对应年份显示数据库内容的类，运行时显示items无法进行遍历是为什么，是不代码写得哪里有问题

public User selectUserBynian(String nian) { // 根据年进行查询
        Connection conn = DbDao.getConnection();
        String sql = "select * from user where nian = " + nian;
        User user = null;
        try {
            PreparedStatement pst = conn.prepareStatement(sql);
            ResultSet rst = pst.executeQuery();
            while (rst.next()) {
                user = new User();
                user.setNian(rst.getString("nian"));
                user.setId(rst.getInt("id")); 
                user.setname(rst.getString("name"));
                user.setId_card(rst.getString("id_card"));
                user.setId_dianzi(rst.getString("id_dianzi"));
                user.setState(rst.getString("state"));              
                user.setYue(rst.getString("yue"));
                user.setRi(rst.getString("ri"));
            }
            rst.close();
            pst.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return user; // 返回
    }

public class NianServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        SimpleDateFormat df = new SimpleDateFormat("yyyy");
        String nian = df.format(new Date());
        UserDao dao = new UserDao();
        User user = dao.selectUserBynian(nian);
        req.setAttribute("nian", user);
        req.getRequestDispatcher("/nianshow.jsp").forward(req, resp);
    }
}

     <c:forEach var="N" items="${nian}"  >     
       <tr>
           <td><input type="text" value="${N.id}" name="id" ></td>
           <td><input type="text" value="${N.name}" name="name"></td>
           <td><input type="text" value="${N.id_card}" name="idcard"></td>
           <td><input type="text" value="${N.id_dianzi}" name="id_dianzi"></td>
           <td><input type="text" value="${N.state}" name="state"></td>
           <td><input type="text" value="${N.nian}" name="nian"></td>
           <td><input type="text" value="${N.yue}" name="yue"></td>
           <td><input type="text" value="${N.ri}" name="ri"></td>
       </tr>   
    </c:forEach> 

错误说Don't know how to iterate over supplied "items" in <forEach>

Answer 1

刚才发现了应该使用public List selectUserBynian(String nian)，刚开始想错了。