classnotfoundException javax/mail/MessagingException

Question

我使用 eclipse/jetty 获取 classnotfoundException javax/mail/MessagingException。

我已将activation.jar、javax.mail-1.5.3.jar 和javaee.jar 添加到我的lib 文件夹和war/web-inf/lib 文件夹的java 构建路径中。

如有任何建议，我们将不胜感激。谢谢你。

Answer 1

您必须在类路径中添加这些 jar 文件，转到您的项目构建路径，在那里您可以看到类路径选项卡，找到您的 jar 并选择它们并保存，之后应该可以工作。

Answer 2

我的错误是我试图在客户端上执行代码。当我将代码移至服务器后，它运行良好，并且不需要 javaee.jar。

Answer 3

任何人都可以帮助我吗，因为我一直在尝试解决这个错误，但我不能

我创建了一个电子邮件创建器 其中一个包含姓名和电子邮件的输入文件，另一个包含电子邮件模板 代码是

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
 import java.util.Properties;
 import javax.mail.*;
 import javax.mail.internet.*;


  public class EmailCreator {
      public static void main(String[] args) {
         String inputFile = "src/input.txt";
         String templateFile = "src/email_template.txt";
    
 // Check if the input file exists and is readable
    if (!isFileReadable(inputFile)) {
        System.err.println("Error: Input file '" + inputFile + "' does not exist or is not readable.");
        return;
    }

    // Check if the template file exists and is readable
    if (!isFileReadable(templateFile)) {
        System.err.println("Error: Template file '" + templateFile + "' does not exist or is not readable.");
        return;
    }
 try (BufferedReader br = new BufferedReader(new FileReader(inputFile))) {
        String line;
        while ((line = br.readLine()) != null) {
            // Split the line into parts using a comma as the delimiter
            String[] parts = line.split(",");
            if (parts.length == 3) {
                String firstName = parts[0].trim();
                String lastName = parts[1].trim();
                String email = parts[2].trim().toLowerCase();

                // Read the email template
                String template = readEmailTemplate(templateFile);

                // Replace placeholders with actual data
                String emailContent = template.replace("{first_name}", firstName)
                                             .replace("{last_name}", lastName)
                                             .replace("{email}", email);

                // Send the email
                sendEmail(email, "{[email protected]}", "Deals!", emailContent);

                System.out.println("Email sent to " + email);
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private static String readEmailTemplate(String templateFile) {
    // Code to read the email template from the file and return it as a string
    // You can implement this method based on your file reading preferences
    // For simplicity, you can use FileReader and BufferedReader as shown above.
    // Make sure to handle exceptions and errors when reading the template.
    // Here's a basic example:

    StringBuilder templateBuilder = new StringBuilder();
    try (BufferedReader reader = new BufferedReader(new FileReader(templateFile))) {
        String line;
        while ((line = reader.readLine()) != null) {
            templateBuilder.append(line).append("\n");
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    return templateBuilder.toString();
}

private static void sendEmail(String toEmail, String fromEmail, String subject, String emailContent) {
    // Code to send an email using JavaMail API
    // You should replace these placeholders with your SMTP server details and email credentials
    String smtpHost = "smtp.gmail.com";
    String smtpPort = "587";
    String smtpUsername = "[email protected]";
    String smtpPassword = "XXXXXXXXXXX";

    Properties properties = new Properties();
    properties.put("mail.smtp.auth", "true");
    properties.put("mail.smtp.starttls.enable", "true");
    properties.put("mail.smtp.host", smtpHost);
    properties.put("mail.smtp.port", smtpPort);

    Session session = Session.getInstance(properties, new Authenticator() {
        @Override
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(smtpUsername, smtpPassword);
        }
    });

    try {
        Message emailMessage = new MimeMessage(session);
        emailMessage.setFrom(new InternetAddress(fromEmail));
        emailMessage.setRecipients(Message.RecipientType.TO, InternetAddress.parse(toEmail));
        emailMessage.setSubject(subject);
        emailMessage.setContent(emailContent, "text/plain");
        Transport.send(emailMessage);
    } catch (MessagingException e) {
        e.printStackTrace();
    }
}
    
    private static boolean isFileReadable(String filePath) {
        File file = new File(filePath);

        // Check if the file exists
        if (!file.exists()) {
            return false;
        }

        // Check if the file is readable
        try {
            FileReader fileReader = new FileReader(file);
            fileReader.close(); // Close the file if it was successfully opened
            return true;
        } catch (IOException e) {
            return false;
        }
    }
}

我已通过属性和构建路径将 javax.mail.jar 文件添加到库中，在将外部 jar 添加到添加到引用库的代码中之后编写代码时，我删除了代码中的错误，但是

在控制台中我收到的错误为 错误：无法初始化主类 EmailCreator 引起原因：java.lang.NoClassDefFoundError：javax/mail/MessagingException

所以，任何人都可以帮助我摆脱这个错误