我必须对主类和JavaMailUtl类进行分类这是我的JavaMailUtl类:
import javax.mail.Authenticator;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
public class JavaMailUtl {
public static void sendMail(String recepient) throws Exception{
System.out.println("Preparing Email");
Properties properties = new Properties();
properties.put("mail.smtp.auth", "true");
properties.put("mail.smtp.starttls.enable", "true");
properties.put("mail.smtp.host", "smtp.gmail.com");
properties.put("mail.smtp.port", "587");
String myAccountEmail = "[email protected]";
String password = "xxxxxxxx";
Session session = Session.getInstance(properties, new Authenticator() {
@Override
protected javax.mail.PasswordAuthentication getPasswordAuthentication() {
return new javax.mail.PasswordAuthentication(myAccountEmail, password);
}
});
Message message = prepareMessage(session, myAccountEmail, recepient);
Transport.send(message);
System.out.println("Message sent!");
}
private static Message prepareMessage(Session session, String myAccountEmail, String recepient){
try {
Message message = new MimeMessage(session);
message.setFrom(new InternetAddress(myAccountEmail));
message.setRecipient(Message.RecipientType.TO, new InternetAddress(recepient));
message.setSubject("Gmail API");
message.setText("This Message sent from Java APP");
} catch (Exception ex) {
Logger.getLogger(JavaMailUtl.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}
}
这是我的主要课程:
public class JavaEmailMessaging {
/**
* @param args the command line arguments
*/
public static void main(String[] args) throws Exception {
JavaMailUtl.sendMail("[email protected]");
}
}
[当我尝试运行项目时,出现以下错误:
Preparing Email
Exception in thread "main" java.lang.NullPointerException
at javax.mail.Transport.send(Transport.java:123)
at mailing.email.messaging.JavaMailUtl.sendMail(JavaMailUtl.java:43)
at mailing.email.messaging.JavaEmailMessaging.main(JavaEmailMessaging.java:18)
多次仔细检查代码,发现我拥有的每个对象都指向正确的位置对我来说没有问题。
您的prepareMessage
方法返回null。在try
之前定义消息,然后返回。
类似这样的东西:
private static Message prepareMessage(Session session, String myAccountEmail, String recepient) {
Message message = null;
try {
message = new MimeMessage(session);
message.setFrom(new InternetAddress(myAccountEmail));
message.setRecipient(Message.RecipientType.TO, new InternetAddress(recepient));
message.setSubject("Gmail API");
message.setText("This Message sent from Java APP");
} catch (Exception ex) {
Logger.getLogger(JavaMailUtl.class.getName()).log(Level.SEVERE, null, ex);
}
return message;
}
希望有所帮助。
EDIT:另外,值得注意的是an enhancement in Java 14应该可以减轻这种情况的痛苦。您将获得有关确切为空的更多信息。