为修复BUG快速写的一个读取邮件(eml)文件中附件名的代码片段，目前状态基本能用

MailAttachmentFilenameDemo.java

package org.xkit.mail.demo;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MailAttachmentFilenameDemo {

	public static void main(String[] args) {
		System.out
				.println(decodeFilename(
						"message/rfc822; name*0=\"16951479.5239.1308559950610.JavaMail.root@localhost.localdomain.e\"; name*1=\"ml\"",
						"name", null, null));

		System.out
				.println(decodeFilename(
						"filename*0*=GB2312''%C1%D9%CA%B1%53%51%4C%A3%AC%D0%DE%B8%C4%C3%DC%C2%EB%B5;filename*1*=%C8%B5%C8",
						"name", null, null));
	}

	public static String decodeFilename(String fileNameStr, String field,
			String encoding, String charset) {
		Pattern pattern = Pattern.compile(("[\\s\\S]*" + field + "[\\s\\S]*$"));
		StringBuilder nameBuilder = new StringBuilder(fileNameStr.length() / 3);
		String[] names = fileNameStr.split(";");
		for (String name : names) {
			String[] kvs = name.split("=", -1);
			Matcher m = pattern.matcher(kvs[0]);
			if (m.find()) {
				String chunk = null;
				// 获取编码
				String[] cv = kvs[1].split("''");
				if (2 == cv.length) {
					charset = cv[0].trim();
					chunk = cv[1].trim();
				} else if (1 == cv.length) {
					chunk = cv[0].trim();
				}
				if (chunk.startsWith("\"")) {
					chunk = chunk.replaceAll("^\"*", "");
				}
				if (chunk.endsWith("\"")) {
					chunk = chunk.replaceAll("\"*$", "");
				}
				nameBuilder.append(chunk);
			}
		}
		// 如果前后有双引号，去掉
		// 如果需要解码，解码

		String result = null;

		if (null != charset) {
			try {
				result = URLDecoder.decode(nameBuilder.toString(), charset);
			} catch (UnsupportedEncodingException e) {
				result = nameBuilder.toString();
				e.printStackTrace();
			}
		} else {
			result = nameBuilder.toString();
		}
		return result;
	}
}