如何将DAO中的值发送回Servlet

Question

我有一个关于如何继续的问题。用户输入电子邮件并单击忘记密码。然后servlet将调用Dao来检查电子邮件是否存在，如果存在，Dao将重置密码。我希望Dao将重置密码发送回servlet，并重定向另一个servlet将电子邮件发送回具有重置密码的用户。有人能解释一下我该怎么做吗？

下面是我的CheckEmailForgotDao

public class CheckEmailForgotDao{
String url = "jdbc:mysql://localhost:3308/mywebapp";
String username = "root";
String password = "root";
String sql = "SELECT * FROM users WHERE email=?";
public boolean check(String uname) {
try {
Class.forName("com.mysql.cj.jdbc.Driver");
Connection con = DriverManager.getConnection(url, username, password);
PreparedStatement st = con.prepareStatement(sql);
st.setString(1, uname);
ResultSet rs = st.executeQuery();
if (rs.next()) {
String randomPassword = RandomStringUtils.randomAlphanumeric(10);
String resetsql = "UPDATE users SET password = ? WHERE email = ?";
PreparedStatement resetst = con.prepareStatement(resetsql);
resetst.setString(1, randomPassword);
resetst.setString(2, uname);
System.out.println(resetst);
resetst.executeUpdate();
}
return true;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return false;
}
}

下面是我的Servlet

@WebServlet("/forgotpassword")
public class ResetPasswordServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public ResetPasswordServlet() {
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String recipient = request.getParameter("email");
String uname = recipient;
CheckEmailForgotDao dao = new CheckEmailForgotDao();
response.setContentType("text/html");
PrintWriter out = response.getWriter();
if (dao.check(uname)) {
request.getRequestDispatcher("/SendEmailResetPassword").include(request, response);

} else {
request.getRequestDispatcher("index.html").include(request, response);
out.println("<script>document.getElementById('err-forgot').innerHTML= 'Email does not exist!'; </script>");
}
}
}

Answer 1

我终于可以做到了。下面是我的代码。

-忘记密码Servlet->CheckEmailForgot

-CheckEmailForgot->检查电子邮件是否存在->重置密码->

-忘记密码Servlet-忘记密码Servlet->使用电子邮件查询密码->EmailForgotDao

-EmailForgotDao->发送电子邮件->忘记密码Servlet->显示发送的电子邮件

@WebServlet("/forgotpassword")
public class ResetPasswordServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public ResetPasswordServlet() {
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String recipient = request.getParameter("email");
String uname = recipient;
CheckEmailForgotDao dao = new CheckEmailForgotDao();
response.setContentType("text/html");
PrintWriter out = response.getWriter();     
if (dao.check(uname)) {
String url = "jdbc:mysql://localhost:3308/mywebapp";
String username = "root";
String password = "root";
String sql = "SELECT * FROM users WHERE email=?";
try {
Class.forName("com.mysql.cj.jdbc.Driver");
Connection con = DriverManager.getConnection(url, username, password);
PreparedStatement st = con.prepareStatement(sql);
st.setString(1, uname);
ResultSet rs = st.executeQuery();
if (rs.next()) {
String newpassword = rs.getString(3);
EmailForgotDao emaildao = new EmailForgotDao();
if (emaildao.sendemailforgot(uname, newpassword)) {
request.getRequestDispatcher("index.html").include(request, response);
out.println(
"<script>document.getElementById('msg-forgot').innerHTML= 'Reset password sent!'; </script>");
}
} else {
request.getRequestDispatcher("index.html").include(request, response);
out.println(
"<script>document.getElementById('msg-forgot').innerHTML= 'Error!'; </script>");
}
} catch (Exception e) {
e.printStackTrace();
}
} else {
request.getRequestDispatcher("index.html").include(request, response);
out.println("<script>document.getElementById('msg-forgot').innerHTML= 'Email does not exist!'; 
</script>");
}
}

上面的servlet使用下面的CheckEmailForgotDao来检查电子邮件是否存在。

1.如果存在，此dao将重置密码并返回true。

2.如果它不存在，这个dao将返回false，servlet将显示电子邮件不存在。

3.如果下面的CheckEmailForgotDao返回true，servlet将查询并获得新的重置密码。

4.然后servlet将使用它来调用另一个EmailForgotDao。

public class CheckEmailForgotDao{
String url = "jdbc:mysql://localhost:3308/mywebapp";
String username = "root";
String password = "root";
String sql = "SELECT * FROM users WHERE email=?";
public boolean check(String uname) {
try {
Class.forName("com.mysql.cj.jdbc.Driver");
Connection con = DriverManager.getConnection(url, username,password);
PreparedStatement st = con.prepareStatement(sql);
st.setString(1, uname);
ResultSet rs = st.executeQuery();
if (rs.next()) {
String randomPassword = RandomStringUtils.randomAlphanumeric(10);
String resetsql = "UPDATE users SET password = ? WHERE email = 
?";
PreparedStatement resetst = con.prepareStatement(resetsql);
resetst.setString(1, randomPassword);
resetst.setString(2, uname);
System.out.println(resetst);
resetst.executeUpdate();
}
return true;
} catch (Exception e) {

e.printStackTrace();
}
return false;
}

下面的EmailForgotDao将发送电子邮件并返回true。然后servlet将显示Reset Password Sent！

如果由于错误而返回false，servlet将显示Error。

public class EmailForgotDao {
public static class SMTPAuthenticator extends Authenticator {
public PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication("[e-mail]", 
"yourpassword");
}
}

public boolean sendemailforgot(String uname, String newpassword) {
String d_uname = "[e-mail]";
String d_password = "yourpassword";
String d_host = "smtp.gmail.com";
int d_port = 465;
String m_to = uname;
String m_from = "[e-mail]";
String m_subject = "Your Password has been reset";
String m_text = "Hi your new password is " + newpassword;
String abc = "text/plain";
Properties props = new Properties();
SMTPAuthenticator auth = new SMTPAuthenticator();
Session ses = Session.getDefaultInstance(props, auth);
MimeMessage msg = new MimeMessage(ses);
try {
msg.setContent(m_text, abc);
msg.setSubject(m_subject);
msg.setFrom(new InternetAddress(m_from));
msg.addRecipient(Message.RecipientType.TO, new InternetAddress(m_to));
Transport transport = ses.getTransport("smtps");
transport.connect(d_host, d_port, d_uname, d_password);
transport.sendMessage(msg, msg.getAllRecipients());
transport.close();

return true;
} catch (Exception e) {
System.out.println(e);

}

return false;
}
}