java - 无法从 Java Web 应用程序发送电子邮件

Question

我无法使用以下代码发送电子邮件。我的库里有所有需要的 jar 。我在 mysql 工作台上连接了一个数据库，我正在从表单操作 =“EmailListServlet”中选取数据，并从数据库中选取用户详细信息。尽管我能够在 netbeans 的输出窗口中接收输出，但我收到了 catch block 中的异常消息。

EmailListServlet

@WebServlet(name = "EmailListServlet", urlPatterns = {"/EmailListServlet"})
public class EmailListServlet extends HttpServlet {

    @EJB
    private EmailSenderBean sendMail;

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        HttpSession session = request.getSession(true);
        session.setMaxInactiveInterval(-1);
        String url ="";

        EntityManager em = DBUtil.getEmFactory().createEntityManager();
        User user= (User) session.getAttribute("theUser");
        String name = request.getParameter("Name");
        System.out.println("Name is"+name);
        String fromEmail = request.getParameter("User_Id");
        System.out.println("Sender Email is"+fromEmail);
        String toEmail = request.getParameter("Friend_Id");
        System.out.println("To Email is"+toEmail);
        String message = request.getParameter("Message");
        System.out.println("Message is"+message);
        fromEmail = "'"+fromEmail+"'";
        String userPwd = user.getPassword();
        System.out.println("Password is" +userPwd);

        try{
            sendMail.SendEmail(name, fromEmail, userPwd, toEmail, message);
            url="/confirmr.jsp";
        }
        catch(Exception e){
            System.out.println("This is an Exception");
        }

        em.close();
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

EmailSenderBean

@Stateless
public class EmailSenderBean {

    public void SendEmail(String name, String fromEmail, String userPwd, String toEmail, String message ){

        Properties props = System.getProperties();
        props.put("mail.smtp.host", "localhost");
        props.put("mail.smtp.auth", "true");
        //props.put("mail.smtp.port", "465");
        props.put("mail.smtp.socketDactory.class", "javax.net.ssl.SSLSocketFactory");
        //props.put("mail.smtp.socketFactory.port", "465");
        props.put("mail.smtp.socketFactory.fallback", "false");

        Session session = Session.getDefaultInstance(props, null);
        session.setDebug(true);

       Message mailMessage = new MimeMessage(session);

        try {
            mailMessage.setFrom(new InternetAddress(fromEmail));
            mailMessage.setRecipient(Message.RecipientType.TO, new InternetAddress(toEmail));
            mailMessage.setContent(message, "text/html");

            Transport transport = session.getTransport("smtp");
            transport.connect("localhost", fromEmail, userPwd);
            transport.sendMessage(mailMessage, mailMessage.getAllRecipients());

        } 
        catch (MessagingException ex) {
            Logger.getLogger(EmailSenderBean.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}



[EmailListServlet] in context with path [/Ojas_App] threw exception
 java.lang.NullPointerException
    at org.uncc.nbad.servlet.EmailListServlet.doPost(EmailListServlet.java:83)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2503)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2492)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745). 

这指向sendMail.SendEmail(name, fromEmail, userPwd, toEmail, message);

Answer 1

两天后我终于能够运行这段代码了。我更新的代码在下面分享

EmailSenderBean.java

public class EmailSenderBean {

// Add business logic below. (Right-click in editor and choose
// "Insert Code > Add Business Method")

public void sendEmail(String name, String fromEmail, String toEmail, String subject, String message) {

    Properties props = System.getProperties();

    props.put("mail.smtp.port", "587");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.starttls.enable", "true");

    String [] toEmails = {toEmail};
    String emailSubject = subject;
String emailBody = message;

    Session session = Session.getDefaultInstance(props, null);
    Message mailMessage = new MimeMessage(session);

    try {
        String fromUser = "youremailid@gmail.com";
        String fromUserEmailPassword = "yourpassword";

        if(fromEmail!=null && !fromEmail.trim().equals("")){
            mailMessage.setFrom(new InternetAddress(fromEmail));
        }
        else{
            mailMessage.setFrom(new InternetAddress(fromUser));
        }
        for (String toEmail1 : toEmails) {
            mailMessage.addRecipient(Message.RecipientType.TO, new InternetAddress(toEmail1));
        }
        mailMessage.setSubject(emailSubject);
        mailMessage.setContent(emailBody, "text/html");

        String emailHost = "smtp.gmail.com";
        Transport transport = session.getTransport("smtp");
        transport.connect(emailHost, fromUser, fromUserEmailPassword);
        transport.sendMessage(mailMessage, mailMessage.getAllRecipients());
        transport.close();
    }
    catch(AddressException ex){
        ex.printStackTrace();
        Logger.getLogger(EmailSenderBean.class.getName()).log(Level.SEVERE, null, ex);
    }
    catch (MessagingException ex) {
        ex.printStackTrace();
        Logger.getLogger(EmailSenderBean.class.getName()).log(Level.SEVERE, null, ex);
    }

}
}

EmailListServlet.java

@WebServlet(name = "EmailListServlet", urlPatterns = {"/EmailListServlet"})
public class EmailListServlet extends HttpServlet {


public EmailSenderBean sendMail;

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

}

// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
 * Handles the HTTP <code>GET</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    doPost(request, response);
}

/**
 * Handles the HTTP <code>POST</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

    String url="";
    response.setContentType("text/html;charset=UTF-8");

    EntityManager em = DBUtil.getEmFactory().createEntityManager();

    String action  = request.getParameter("action");
    String name = request.getParameter("Name");
    String fromEmail = request.getParameter("User_Id");
    String toEmail = request.getParameter("Friend_Id");
    String message = request.getParameter("Message");


    sendMail = new EmailSenderBean();

    String subject ="";
    if(action.equals("contact")){
        subject = "Contact made via ORNSurveys";
        message = name+" wants to contact you via ORN SURVEYS"+message;
        sendMail.sendEmail(name, null, toEmail, subject, message);
        url = "/confirmc.jsp";
    }else if(action.equals("recommend")){
        subject = "Recommendation to join ORNSurveys";
        message = name+" wants to recommend you to join ORN SURVEYS"+message;
        sendMail.sendEmail(name, fromEmail, toEmail, subject, message);
        url = "/confirmr.jsp";
    }
    em.close();
    getServletContext()
            .getRequestDispatcher(url)
            .forward(request, response);

}
}