使用 Java Mail 下载附件

Download attachments using Java Mail

提问by folone

Now that I`ve downloaded all the messages, and store them to

现在我已经下载了所有的消息，并将它们存储到

Message[] temp;

How do I get the list of attachments for each of those messages to

如何获取每封邮件的附件列表

List<File> attachments;

Note:no thirdparty libs, please, just JavaMail.

注意：请不要使用第三方库，只需 JavaMail。

采纳答案by David Rabinowitz

Without exception handling, but here goes:

没有异常处理，但这里是：

List<File> attachments = new ArrayList<File>();
for (Message message : temp) {
    Multipart multipart = (Multipart) message.getContent();

    for (int i = 0; i < multipart.getCount(); i++) {
        BodyPart bodyPart = multipart.getBodyPart(i);
        if(!Part.ATTACHMENT.equalsIgnoreCase(bodyPart.getDisposition()) &&
               StringUtils.isBlank(bodyPart.getFileName())) {
            continue; // dealing with attachments only
        } 
        InputStream is = bodyPart.getInputStream();
        // -- EDIT -- SECURITY ISSUE --
        // do not do this in production code -- a malicious email can easily contain this filename: "../etc/passwd", or any other path: They can overwrite _ANY_ file on the system that this code has write access to!
//      File f = new File("/tmp/" + bodyPart.getFileName());
        FileOutputStream fos = new FileOutputStream(f);
        byte[] buf = new byte[4096];
        int bytesRead;
        while((bytesRead = is.read(buf))!=-1) {
            fos.write(buf, 0, bytesRead);
        }
        fos.close();
        attachments.add(f);
    }
}

回答by mefi

Question is very old, but maybe it will help someone. I would like to expand David Rabinowitz`s answer.

问题很老，但也许它会帮助某人。我想扩展 David Rabinowitz 的回答。

if(!Part.ATTACHMENT.equalsIgnoreCase(bodyPart.getDisposition()))

should not return all atachments as you expect, because you can have mail where mixed part is without defined disposition.

不应该像您期望的那样返回所有附件，因为您可以拥有混合部分没有定义处置的邮件。

   ----boundary_328630_1e15ac03-e817-4763-af99-d4b23cfdb600
Content-Type: application/octet-stream;
    name="00000000009661222736_236225959_20130731-7.txt"
Content-Transfer-Encoding: base64

so in this case, you can also check for filename. Like this:

所以在这种情况下，您还可以检查文件名。像这样：

if (!Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition()) && StringUtils.isBlank(part.getFileName())) {...}

EDIT

编辑

there is whole working code using condition descibed above.. Because each part can encapsulate another parts and attachment should be nested in, recursion is used to traverse through all parts

有使用上面描述的条件的完整工作代码..因为每个部分都可以封装另一个部分并且应该嵌套附件，所以使用递归遍历所有部分

public List<InputStream> getAttachments(Message message) throws Exception {
    Object content = message.getContent();
    if (content instanceof String)
        return null;        

    if (content instanceof Multipart) {
        Multipart multipart = (Multipart) content;
        List<InputStream> result = new ArrayList<InputStream>();

        for (int i = 0; i < multipart.getCount(); i++) {
            result.addAll(getAttachments(multipart.getBodyPart(i)));
        }
        return result;

    }
    return null;
}

private List<InputStream> getAttachments(BodyPart part) throws Exception {
    List<InputStream> result = new ArrayList<InputStream>();
    Object content = part.getContent();
    if (content instanceof InputStream || content instanceof String) {
        if (Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition()) || StringUtils.isNotBlank(part.getFileName())) {
            result.add(part.getInputStream());
            return result;
        } else {
            return new ArrayList<InputStream>();
        }
    }

    if (content instanceof Multipart) {
            Multipart multipart = (Multipart) content;
            for (int i = 0; i < multipart.getCount(); i++) {
                BodyPart bodyPart = multipart.getBodyPart(i);
                result.addAll(getAttachments(bodyPart));
            }
    }
    return result;
}

回答by kommradHomer

Some time saver for the code where you save the attachment file :

保存附件文件的代码可以节省一些时间：

with javax mail version 1.4and after , you can say

使用 javax 邮件版本1.4及之后，您可以说

// SECURITY LEAK - do not do this! Do not trust the 'getFileName' input. Imagine it is: "../etc/passwd", for example.
// bodyPart.saveFile("/tmp/" + bodyPart.getFileName());

instead of

代替

    InputStream is = bodyPart.getInputStream();
    File f = new File("/tmp/" + bodyPart.getFileName());
    FileOutputStream fos = new FileOutputStream(f);
    byte[] buf = new byte[4096];
    int bytesRead;
    while((bytesRead = is.read(buf))!=-1) {
        fos.write(buf, 0, bytesRead);
    }
    fos.close();

回答by Stackee007

You can simply use Apache Commons Mail API MimeMessageParser - getAttachmentList()along Commons IO and Commons Lang.

您可以简单地使用 Apache Commons Mail API MimeMessageParser - getAttachmentList()以及 Commons IO 和 Commons Lang。

MimeMessageParser parser = ....
parser.parse();
for(DataSource dataSource : parser.getAttachmentList()) {

    if (StringUtils.isNotBlank(dataSource.getName())) {}

        //use apache commons IOUtils to save attachments
        IOUtils.copy(dataSource.getInputStream(), ..dataSource.getName()...)
    } else {
        //handle how you would want attachments without file names
        //ex. mails within emails have no file name
    }
}