html - 电子邮件附件中的所有文件类型都可以使用 java 邮件 API 读取吗？

Question

我正在使用 java 邮件阅读电子邮件附件。这是我使用的代码：

public static void main(String args[]) throws Exception {
        String host = "172.16.0.186";
        String user = "admin";
        String password = "1234";
        // Get system properties
        Properties properties = System.getProperties();
        // Get the default Session object.
        Session session = Session.getDefaultInstance(properties);
        // Get a Store object that implements the specified protocol.
        Store store = null;
        try {
            store = session.getStore("pop3");
            //Connect to the current host using the specified username and password.
            store.connect(host, user, password);
        } catch (Exception e) {
            logger.warn("An exception occured," + e);
        }
        //Create a Folder object corresponding to the given name.
        Folder folder = store.getFolder("Inbox");
        // Open the Folder.
        folder.open(Folder.READ_WRITE);
        Message[] message = folder.getMessages();
        for (int a = 0; a < message.length; a++) {
            System.out.println("-------------" + (a + 1) + "-----------");
            System.out.println(message[a].getSentDate());
            Multipart multipart = (Multipart) message[a].getContent();
            for (int i = 0; i < multipart.getCount(); i++) {
                //System.out.println(i);
                //System.out.println(multipart.getContentType());
                BodyPart bodyPart = multipart.getBodyPart(i);
                InputStream stream = bodyPart.getInputStream();
                File file = new File("C:\\Attachments\\" + bodyPart.getFileName());
                BufferedReader br = new BufferedReader(
                    new InputStreamReader(stream));
                while (br.ready()) {
                    System.out.println(br.readLine());
                }
                saveFile(bodyPart.getFileName(), stream);
                attachments.add(file);
                System.out.println();
            }
            System.out.println();
        }
        folder.close(true);
        store.close();
    }

    /**
     * Save file.
     * 
     * @param filename
     *        the filename
     * @param input
     *        the input
     */
    public static void saveFile(String filename, InputStream input) {
        System.out.println(filename);
        try {
            if (filename == null) {
                //filename = File.createTempFile("VSX", ".out").getName();
                return;
            }
            // Do no overwrite existing file
            filename = "C:\\Attachments\\" + filename;
            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()) >= 0) {
                bos.write(aByte);
            }
            bos.flush();
            bos.close();
            bis.close();
        } // end of try()
        catch (IOException exp) {
            System.out.println("IOException:" + exp);
        }
    } //end of saveFile()
}

发生以下异常： javax.mail.NoSuchProviderException: pop3

最后一个问题：如果可以使用 java 邮件 API 读取所有文件类型，那么我们如何读取 excel 文件、HTML 文件或 word 文件。