無法從Java Web應用程序發送電子郵件

Question

我無法使用以下代碼發送電子郵件。我的圖書館裏有所有需要的罐子。我有一個連接到mysql工作臺的數據庫，我從表單action =「EmailListServlet」和數據庫中的用戶詳細信息中選擇數據。儘管我能夠在netbeans的輸出窗口中接收輸出，但我收到了catch塊中的異常消息。

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). 

這指向sendMail.SendEmail（姓名，fromEmail，userPwd，toEmail，消息）;

Answer 1

終於在2天后，我能夠運行此代碼。我更新的代碼如下

共享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); 

} 
}