java - 在 struts 1.3 中如何从数据库中检索数据并使用 DAO 显示它

Question

*我是 struts 的新手。我正在制作简单的登录页面，通过从数据库中检索来显示用户名和密码。我正在使用 DAO。 我有 LoginDAO.java、LoginAction.java 和 Displaydata.jsp 页面。 *

LoginDAO.java

 public boolean login(String user,String pass) throws SQLException
     {
         Connection con = getConnection();

         Statement st;
        try {
            st = con.createStatement();



                  st.executeQuery("select * from login where Username='" + user + "' and Password='" + pass + "'");


                return true;
            } catch (SQLException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

         return false;

     } 

LoginAction.java

public class LoginAction extends Action

{

    public ActionForward execute(ActionMapping mapping, ActionForm form,
        HttpServletRequest request, HttpServletResponse response)
        throws Exception {



    DynaValidatorForm rf= (DynaValidatorForm) form;

 String username = rf.get("username").toString();
 String password = rf.get("password").toString();
 HttpSession session=request.getSession();
 session.setAttribute("user", username);

 Login dao= new Login();

 if(dao.login(username,password))
 {
      System.out.println("GOT");
        return mapping.findForward("success");}
    else
        {System.out.println("NOT");
    return mapping.findForward("failure");
        }
}
}

and also what do i write in Dislpaydata.jsp to display username and password in it dont want any java code in it. Thankyou

Answer 1

没错。前段时间我使用 Struts 1.x 和 MySql 构建了一个带有登录的应用程序。

登录 Action

public ActionForward login( ... ) throws Exception {
    String forward;
    final String mail = PropertyUtils.getProperty(form, "mail");
    final String password = PropertyUtils.getProperty(form, "password");
    if (LoginService.getInstance().validate(mail, password)) {
        // Do something e.g. put name of user in session
        forward = SUCCESS;
    } else {
        forward = ERROR;
    }
    return mapping.findForward(forward);
}

登录服务

public boolean validate(final String mail, final String password) 
                                                        throws ServiceException {
    try {
        final boolean valid;

        // Validate null and empty

        // Validate with DB
        final UserDAO dao = new UserDAO();
        final User user = dao.findByPk(mail);
        if (user == null) {
            valid = false;
        } else {
            if (password.equals(user.getPassword())) {
                valid = true;
            } else {
                valid = false;
            }
        }
        return valid;
    } catch (DAOException e) {
        throw new ServiceException("Error validating user and password.", e);
    }
}

UserDAO

private static final String FIND_BY_PK_SQL 
                 = "SELECT mail, name, password, admin FROM user WHERE mail = ?";

public User findByPk(final String mail) throws DAOException {
    Connection conn = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    try {
        conn = getConnection();
        ps = conn.prepareStatement(FIND_BY_PK_SQL);
        ps.setString(1, mail); // PK, NOT NULL
        rs = ps.executeQuery();
        if (rs.next()) {
            return fill(rs);
        }
        return null;
    } catch (final SQLException e) {
        throw new DAOException(e);
    } finally {
        // Close DB resources
    }
}

private User fill(final ResultSet rs) throws SQLException {
    final User user = new User();
    user.setMail(rs.getString("mail"));
    user.setName(rs.getString("name"));
    user.setPassword(rs.getString("password"));
    user.setAdmin(rs.getBoolean("admin"));
    return user;
}

在我的例子中，我有一个表 user，其中 mail 作为主键。有多种形式。

更多例子:

• Building a Login Application
• Struts Login Application Using Action Form Tutorial | DZone
• Creating a Email Login Web Application with Struts

---

例如从数据库中显示 session 范围内变量用户的名称:

登录 Action

if (LoginService.getInstance().validate(mail, password)) {
    final HttpSession session = request.getSession();
    final User user = UserService.getInstance().getUser(mail);
    session.setAttribute("user", user);
    forward = SUCCESS;
}

首页.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>

Welcome,
<bean:write scope="session" name="user" property="name" filter="false" />