After overcoming frustration about WebView.saveWebArchive()
format change in Android 4.4, I tried the "unknown google project" Chitranshu Asthana mentioned in his answer, but code provided there is slow (~10s for 1MB *.mht file with a dozen of pictures) and doesn't handle attached file names correctly.
MHT Unpack library combined with Java Mail for Android (not the one provided by Oracle) worked perfectly for me.
EDIT: Fixed the link to MHT Unpack library. Also, here's usage example:
// contentPath - path to input .mht file
public static String unpackMht(String contentPath) throws IOException {
// dstPath - path where file will be unpacked
String dstPath = openTempDir(null) + File.separator;
String indexFileName = dstPath + new File(contentPath).getName();
try {
Collection<Attachment> attachments = MHTUnpack.unpack(new File(contentPath));
for (Attachment attachment : attachments) {
String filename = attachment.getFileName();
String path = filename == null ? indexFileName : dstPath + filename;
File newFile = new File(path);
if (newFile.exists()) {
newFile.delete();
}
attachment.saveFile(path);
}
return indexFileName;
} catch (MessagingException e) {
throw new IOException(e);
}
}