Java 阅读带有附件文件的邮件时缺少起始边界异常

Missing start boundary Exception when reading messages with an attachment file

提问by Stardust

I don't know why I'm getting the following exception when reading a mail with an attachment file from mail server:

我不知道为什么在从邮件服务器读取带有附件文件的邮件时会出现以下异常：

Exception in thread "main" javax.mail.MessagingException: Missing start boundary

        at javax.mail.internet.MimeMultipart.parsebm<MimeMultipart.java:872)
        at javax.mail.internet.MimeMultipart.parse<MimeMultipart.java:493)
        at javax.mail.internet.MimeMultipart.getCount<MimeMultipart.java:240)
        at GetParts.handleMultipart(GetParts.java:57)
        at GetParts.main(GetParts.java:42)

The file which I'm using to read those messages is:

我用来阅读这些消息的文件是：

import java.io.*;
import java.util.Properties;
import javax.mail.*;
import javax.mail.internet.*;

public class GetParts {
  public static void main (String args[]) 
      throws Exception {
    String host = args[0];
    String username = args[1];
    String password = args[2];

    // Get session
    Properties props=new Properties();
    props.put("mail.mime.multipart.ignoremissingboundaryparamete",true);
    Session session = Session.getInstance(
      props, null);
ContentType ct=new ContentType();
    // Get the store
    Store store = session.getStore("pop3");
    store.connect(host, username, password);

    // Get folder
    Folder folder = store.getFolder("INBOX");
    folder.open(Folder.READ_ONLY);

    BufferedReader reader = new BufferedReader (
      new InputStreamReader(System.in));

    // Get directory
    Message message[] = folder.getMessages();
    for (int i=0, n=message.length; i<n; i++) {
       System.out.println(i + ": "
         + message[i].getFrom()[0] 
         + "\t" + message[i].getSubject());
          //message[i].setHeader("Content-Type","multipart/mixed");
      System.out.println("Do you want to get the content? [YES to read/QUIT to end]");
      String line = reader.readLine();
      if ("YES".equals(line)) {
        Object content = message[i].getContent();
        if (content instanceof Multipart) {
          handleMultipart((Multipart)content);
        } else {
          handlePart(message[i]);
        }
      } else if ("QUIT".equals(line)) {
        break;
      }
    }

    // Close connection 
    folder.close(false);
    store.close();
  }
  public static void handleMultipart(Multipart multipart) 
      throws MessagingException, IOException {
      System.out.println(multipart.getCount());
    for (int i=0, n=multipart.getCount(); i<n; i++) {
      handlePart(multipart.getBodyPart(i));
    }
  }
  public static void handlePart(Part part) 
      throws MessagingException, IOException {
    String disposition = part.getDisposition();
    System.out.println("Disposition "+disposition);
    String contentType = part.getContentType();
    System.out.println("contentType "+contentType);
    if (disposition == null) { // When just body
      System.out.println("Null: "  + contentType);
      // Check if plain
      if ((contentType.length() >= 10) && 
          (contentType.toLowerCase().substring(
           0, 10).equals("text/plain"))) {
        part.writeTo(System.out);
      } else { // Don't think this will happen
        System.out.println("Other body: " + contentType);
        part.writeTo(System.out);
      }
    } else if (disposition.equalsIgnoreCase(Part.ATTACHMENT)) {
      System.out.println("Attachment: " + part.getFileName() + 
        " : " + contentType);
      saveFile(part.getFileName(), part.getInputStream());
    } else if (disposition.equalsIgnoreCase(Part.INLINE)) {
      System.out.println("Inline: " + 
        part.getFileName() + 
        " : " + contentType);
      saveFile(part.getFileName(), part.getInputStream());
    } else {  // Should never happen
      System.out.println("Other: " + disposition);
    }
  }
  public static void saveFile(String filename,
      InputStream input) throws IOException {
    if (filename == null) {
      filename = File.createTempFile("xx", ".out").getName();
    }
    // Do no overwrite existing file
    File file = new File(filename);
    for (int i=0; file.exists(); i++) {
      file = new File(filename+i);
    }
    FileOutputStream fos = new FileOutputStream(file);
    BufferedOutputStream bos = new BufferedOutputStream(fos);

    BufferedInputStream bis = new BufferedInputStream(input);
    int aByte;
    while ((aByte = bis.read()) != -1) {
      bos.write(aByte);
    }
    bos.flush();
    bos.close();
    bis.close();
  }
}

回答by Jordi

I've just had the same problem. The boundary is specified within the Multipart Content-Type. You can find further information in this source. You can also watch the one of your current Message using the getContentType()function. In my case I obtained this result:

我刚刚遇到了同样的问题。边界在 Multipart Content-Type 中指定。您可以在此来源中找到更多信息。您还可以使用该getContentType()功能观看您当前的消息之一。在我的情况下，我得到了这个结果：

multipart/mixed; boundary=--boundary_25_2d74d02b-d0d6-4f28-a311-4d1b7d107417

So the getCount()function uses this boundary to separate all the parts that compose the multiple part. Looks like there could be cases in which this boundary is corrupted.

因此该getCount()函数使用此边界来分隔构成多个部分的所有部分。看起来可能存在此边界损坏的情况。

The mail.mime.multipart.ignoreexistingboundaryparameter System property may be set to true to cause any boundary to be ignored and instead search for a boundary line in the message as with mail.mime.multipart.ignoremissingboundaryparameter.

mail.mime.multipart.ignoreexistingboundaryparameter 系统属性可以设置为 true 以导致任何边界被忽略，而是像使用 mail.mime.multipart.ignoremissingboundaryparameter 一样在邮件中搜索边界线。

I followed this instructions and everything works all right. I added the code below:

我按照此说明进行操作，一切正常。我在下面添加了代码：

System.setProperty("mail.mime.multipart.ignoreexistingboundaryparameter", "true");

Hope it helps!

希望能帮助到你！

回答by Alex Metry

try to set mode on the multipartEntityBuilder ex: multipartEntityBuilder.setMode(HttpMultipartMode.RFC6532);

尝试在 multipartEntityBuilder 上设置模式，例如： multipartEntityBuilder.setMode(HttpMultipartMode.RFC6532);