javax.activation.UnsupportedDataTypeException:没有MIME类型multipart/mixed的对象DCH; 边界

Question

目前我正在编写一个将要监听目录的代码.当使用.apk文件更新目录时,我会将带有此.apk文件的邮件发送到gmail帐户.我在我的程序中使用Jnotify和JAVA Mail.

我得到的错误是,

javax.mail.MessagingException: IOException while sending message;
  nested exception is:
javax.activation.UnsupportedDataTypeException: no object DCH for MIME type multipart/mixed; boundary="----=_Part_0_145238.1392728439484"

我在stackoverflow中寻找了解决方案以寻求帮助,但没有一个在哪里有用.

提前致谢

public void fileCreated(int wd, String rootPath, String name) {
    print("created " + rootPath + " : " + name);

    if (name.contains(".apk"))
      SendEmail(name);
    else
        System.out.println("Not the APK file");
}

void SendEmail(String strname){
    String Path = "D:/POC/Email/apk folder/"+strname;
    System.out.println("Path->" + Path);

    Properties props = new Properties();
    props.put("mail.smtp.host","173.194.78.108");
    props.put("mail.smtp.socketFactory.port", "465");
    props.put("mail.smtp.socketFactory.class","javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.auth","true");
    props.put("mail.smtp.port","465");

    System.out.println("Properties has been set properly");

    Session session = Session.getDefaultInstance(props,
        new javax.mail.Authenticator(){
            protected PasswordAuthentication getPasswordAuthentication(){
                return new PasswordAuthentication("SenderEmailID@gmail.com", "senderPassword");
            }
        }
    );

    System.out.println("Session Created successfully");

    try{
        Message message = new MimeMessage(session); 
        message.setFrom(new InternetAddress("SenderEmailID@gmail.com"));
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("ToReceiverEmailID@gmail.com"));
        message.setSubject("Android : " + strname);

        MimeBodyPart msgbody = new MimeBodyPart();
        msgbody.setText("This is the message content which is sent using JAVA MAIL 1.4.5");
        Multipart mulpart = new MimeMultipart();
        mulpart.addBodyPart(msgbody);

        //Attachement Starts here.
        msgbody = new MimeBodyPart();
        javax.activation.DataSource source = new FileDataSource(Path);
        msgbody.setDataHandler(new DataHandler(source));
        msgbody.setFileName(strname);
        message.setContent(mulpart);

        System.out.println("Attached the message going to start transporting the mail");

        //If I've the code before sending the email is getting sent but without attachment. 
        //Thread.currentThread().setContextClassLoader( getClass().getClassLoader() );

        Transport.send(message);
        System.out.println("Mail Sent successfully");
    }
    catch(MessagingException msg){
        msg.printStackTrace();
    }
    catch(Exception e){
        e.printStackTrace();
    }
}

Answer 1

JavaMail依赖于一些配置文件来将MIME类型映射到Java类(例如,multipart/mixedto javax.mail.internet.MimeMultipart).使用应用程序的ClassLoader加载这些配置文件.如果ClassLoader无法正常运行,则找不到这些配置文件.

您可以简单地添加下面的行...来解决问题.

MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap(); 
mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html"); 
mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml"); 
mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain"); 
mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed"); 
mc.addMailcap("message/rfc822;; x-java-content- handler=com.sun.mail.handlers.message_rfc822"); 

Answer 2

通过以下两个步骤可以解决此问题.

1. 确保java邮件是1.4.7.(以前我使用1.4.5导致所有混淆).从http://www.oracle.com/technetwork/java/index-138643.html下载
2. 在发送消息之前添加这段代码,Thread.currentThread().setContextClassLoader(getClass().getClassLoader());

Answer 3

在发送电子邮件之前添加当前线程是解决方案:

Thread.currentThread().setContextClassLoader( getClass().getClassLoader() );

Answer 4

我正忙于将Java 8项目转换为Java10。与此同时，我一直在更新所有依赖项。我遇到了类似的例外，上述任何解决方案都不适合我。

我的pom.xml中包含以下内容：

<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.1</version>
</dependency>

我进行了更多研究，发现以下链接：

http://www.jguru.com/faq/view.jsp?EID=237257

因此，我尝试将以下依赖项添加到我的pom.xml中：

<dependency>
    <groupId>javax.activation</groupId>
    <artifactId>activation</artifactId>
    <version>1.1.1</version>
 </dependency>

解决了这个问题，我得以再次发送带有附件的邮件。