import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Session;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import java.io.*;
import java.util.Enumeration;


public class Mht2HtmlUtil {

    public static void main(String[] args) throws Exception {
        mht2html("C:\\Users\\Administrator\\Desktop\\028初中阶段校数、班数.mht", "d:\\test.htm");
    }


    /**
     * 将 mht文件转换成 html文件
     *
     * @param srcMht   // mht 文件的位置
     * @param descHtml // 转换后输出的HTML的位置
     */
    public static void mht2html(String srcMht, String descHtml) {
        try {
            InputStream fis = new FileInputStream(srcMht);
            Session mailSession = Session.getDefaultInstance(
                    System.getProperties(), null);
            MimeMessage msg = new MimeMessage(mailSession, fis);
            Object content = msg.getContent();
            if (content instanceof Multipart) {
                MimeMultipart mp = (MimeMultipart) content;
                MimeBodyPart bp1 = (MimeBodyPart) mp.getBodyPart(0);

                // 获取mht文件内容代码的编码
                String strEncodng = getEncoding(bp1);

                // 获取mht文件的内容
                String strText = getHtmlText(bp1, strEncodng);
                if (strText == null)
                    return;
                // 最后保存HTML文件
                SaveHtml(strText, descHtml);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    /**
     * 将提取出来的html内容写入保存的路径中。
     *
     * @param s_HtmlTxt
     * @param s_HtmlPath
     */
    public static boolean SaveHtml(String s_HtmlTxt, String s_HtmlPath) {
        try {
            Writer out = null;
            out = new OutputStreamWriter(
                    new FileOutputStream(s_HtmlPath, false), "utf-8");
            out.write(s_HtmlTxt);
            out.close();
        } catch (Exception e) {
            return false;
        }
        return true;
    }

    /**
     * 获取mht文件中的内容代码
     *
     * @param bp
     * @param strEncoding 该mht文件的编码
     * @return
     */
    private static String getHtmlText(MimeBodyPart bp, String strEncoding) {
        InputStream textStream = null;
        BufferedInputStream buff = null;
        BufferedReader br = null;
        Reader r = null;
        try {
            textStream = bp.getInputStream();
            buff = new BufferedInputStream(textStream);
            r = new InputStreamReader(buff, strEncoding);
            br = new BufferedReader(r);
            StringBuffer strHtml = new StringBuffer("");
            String strLine = null;
            while ((strLine = br.readLine()) != null) {
                System.out.println(strLine);
                strHtml.append(strLine + "\r\n");
            }
            br.close();
            r.close();
            textStream.close();
            return strHtml.toString();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (br != null)
                    br.close();
                if (buff != null)
                    buff.close();
                if (textStream != null)
                    textStream.close();
            } catch (Exception e) {
            }
        }
        return null;
    }

    /**
     * 获取mht网页文件中内容代码的编码
     *
     * @param bp
     * @return
     */
    private static String getEncoding(MimeBodyPart bp) {
        if (bp == null) {
            return null;
        }
        try {
            Enumeration list = bp.getAllHeaders();
            while (list.hasMoreElements()) {
                javax.mail.Header head = (javax.mail.Header) list.nextElement();
                if (head.getName().equalsIgnoreCase("Content-Type")) {
                    String strType = head.getValue();
                    int pos = strType.indexOf("charset=");
                    if (pos >= 0) {
                        String strEncoding = strType.substring(pos + 8,
                                strType.length());
                        if (strEncoding.startsWith("\"")
                                || strEncoding.startsWith("\'")) {
                            strEncoding = strEncoding.substring(1,
                                    strEncoding.length());
                        }
                        if (strEncoding.endsWith("\"")
                                || strEncoding.endsWith("\'")) {
                            strEncoding = strEncoding.substring(0,
                                    strEncoding.length() - 1);
                        }
                        if (strEncoding.toLowerCase().compareTo("gb2312") == 0) {
                            strEncoding = "gbk";
                        }
                        return strEncoding;
                    }
                }
            }
        } catch (MessagingException e) {
            e.printStackTrace();
        }
        return null;
    }
}