An InternetHeader object with a null value is used as a placeholder for headers of that name, to preserve the order of headers. A placeholder InternetHeader object with a name of ":" marks the location in the list of headers where new headers are added by default. 

since: JavaMail - 1.4

 public InternetHeaders() 
{
 
   	headers = new ArrayList(40); 
	headers.add(new InternetHeader("Return-Path", null));
	headers.add(new InternetHeader("Received", null));
	headers.add(new InternetHeader("Resent-Date", null));
	headers.add(new InternetHeader("Resent-From", null));
	headers.add(new InternetHeader("Resent-Sender", null));
	headers.add(new InternetHeader("Resent-To", null));
	headers.add(new InternetHeader("Resent-Cc", null));
	headers.add(new InternetHeader("Resent-Bcc", null));
	headers.add(new InternetHeader("Resent-Message-Id", null));
	headers.add(new InternetHeader("Date", null));
	headers.add(new InternetHeader("From", null));
	headers.add(new InternetHeader("Sender", null));
	headers.add(new InternetHeader("Reply-To", null));
	headers.add(new InternetHeader("To", null));
	headers.add(new InternetHeader("Cc", null));
	headers.add(new InternetHeader("Bcc", null));
	headers.add(new InternetHeader("Message-Id", null));
	headers.add(new InternetHeader("In-Reply-To", null));
	headers.add(new InternetHeader("References", null));
	headers.add(new InternetHeader("Subject", null));
	headers.add(new InternetHeader("Comments", null));
	headers.add(new InternetHeader("Keywords", null));
	headers.add(new InternetHeader("Errors-To", null));
	headers.add(new InternetHeader("MIME-Version", null));
	headers.add(new InternetHeader("Content-Type", null));
	headers.add(new InternetHeader("Content-Transfer-Encoding", null));
	headers.add(new InternetHeader("Content-MD5", null));
	headers.add(new InternetHeader(":", null));
	headers.add(new InternetHeader("Content-Length", null));
	headers.add(new InternetHeader("Status", null));
}

Create an empty InternetHeaders object. Placeholder entries are inserted to indicate the preferred order of headers.

 public InternetHeaders(InputStream is) throws MessagingException 
{
   	headers = new ArrayList(40); 
	load(is);
}

Read and parse the given RFC822 message stream till the blank line separating the header from the body. The input stream is left positioned at the start of the body. The header lines are stored internally.

For efficiency, wrap a BufferedInputStream around the actual input stream and pass it as the parameter.

No placeholder entries are inserted; the original order of the headers is preserved.

Parameters:

is - RFC822 input stream

 public  void addHeader(String name,
    String value) 
{
	int pos = headers.size();
	boolean addReverse =
	    name.equalsIgnoreCase("Received") ||
	    name.equalsIgnoreCase("Return-Path");
	if (addReverse)
	    pos = 0;
	for (int i = headers.size() - 1; i  >= 0; i--) {
	    InternetHeader h = (InternetHeader)headers.get(i);
	    if (name.equalsIgnoreCase(h.getName())) {
		if (addReverse) {
		    pos = i;
		} else {
		    headers.add(i + 1, new InternetHeader(name, value));
		    return;
		}
	    }
	    // marker for default place to add new headers
	    if (h.getName().equals(":"))
		pos = i;
	}
	headers.add(pos, new InternetHeader(name, value));
}

Add a header with the specified name and value to the header list.

The current implementation knows about the preferred order of most well-known headers and will insert headers in that order. In addition, it knows that Received headers should be inserted in reverse order (newest before oldest), and that they should appear at the beginning of the headers, preceeded only by a possible Return-Path header.

Note that RFC822 headers can only contain US-ASCII characters.

 public  void addHeaderLine(String line) 
{
	try {
	    char c = line.charAt(0);
	    if (c == ' ' || c == '\t') {
		InternetHeader h =
		    (InternetHeader)headers.get(headers.size() - 1);
		h.line += "\r\n" + line;
	    } else
		headers.add(new InternetHeader(line));
	} catch (StringIndexOutOfBoundsException e) {
	    // line is empty, ignore it
	    return;
	} catch (NoSuchElementException e) {
	    // XXX - vector is empty?
	}
}

Add an RFC822 header line to the header store. If the line starts with a space or tab (a continuation line), add it to the last header line in the list. Otherwise, append the new header line to the list.

Note that RFC822 headers can only contain US-ASCII characters

 public Enumeration getAllHeaderLines() 
{
 
	return (getNonMatchingHeaderLines(null));
}

Return all the header lines as an Enumeration of Strings.

 public Enumeration getAllHeaders() 
{
	return (new matchEnum(headers, null, false, false));
}

Return all the headers as an Enumeration of javax.mail.Header objects.

 public String[] getHeader(String name) 
{
	Iterator e = headers.iterator();
	// XXX - should we just step through in index order?
	List v = new ArrayList(); // accumulate return values
	while (e.hasNext()) {
	    InternetHeader h = (InternetHeader)e.next();
	    if (name.equalsIgnoreCase(h.getName()) && h.line != null) {
		v.add(h.getValue());
	    }
	}
	if (v.size() == 0)
	    return (null);
	// convert List to an array for return
	String r[] = new String[v.size()];
	r = (String[])v.toArray(r);
	return (r);
}

Return all the values for the specified header. The values are String objects. Returns null if no headers with the specified name exist.

 public String getHeader(String name,
    String delimiter) 
{
	String s[] = getHeader(name);
	if (s == null)
	    return null;
	if ((s.length == 1) || delimiter == null)
	    return s[0];
	StringBuffer r = new StringBuffer(s[0]);
	for (int i = 1; i <  s.length; i++) {
	    r.append(delimiter);
	    r.append(s[i]);
	}
	return r.toString();
}

Get all the headers for this header name, returned as a single String, with headers separated by the delimiter. If the delimiter is null, only the first header is returned. Returns null if no headers with the specified name exist.

 public Enumeration getMatchingHeaderLines(String[] names) 
{
	return (new matchEnum(headers, names, true, true));
}

Return all matching header lines as an Enumeration of Strings.

 public Enumeration getMatchingHeaders(String[] names) 
{
	return (new matchEnum(headers, names, true, false));
}

Return all matching javax.mail.Header objects.

 public Enumeration getNonMatchingHeaderLines(String[] names) 
{
	return (new matchEnum(headers, names, false, true));
}

Return all non-matching header lines

 public Enumeration getNonMatchingHeaders(String[] names) 
{
	return (new matchEnum(headers, names, false, false));
}

Return all non-matching javax.mail.Header objects.

 public  void load(InputStream is) throws MessagingException 
{
	// Read header lines until a blank line. It is valid
	// to have BodyParts with no header lines.
	String line;
	LineInputStream lis = new LineInputStream(is);
	String prevline = null;	// the previous header line, as a string
	// a buffer to accumulate the header in, when we know it's needed
	StringBuffer lineBuffer = new StringBuffer();
	try {
	    //while ((line = lis.readLine()) != null) {
	    do {
		line = lis.readLine();
		if (line != null &&
			(line.startsWith(" ") || line.startsWith("\t"))) {
		    // continuation of header
		    if (prevline != null) {
			lineBuffer.append(prevline);
			prevline = null;
		    }
		    lineBuffer.append("\r\n");
		    lineBuffer.append(line);
		} else {
		    // new header
		    if (prevline != null)
			addHeaderLine(prevline);
		    else if (lineBuffer.length()  > 0) {
			// store previous header first
			addHeaderLine(lineBuffer.toString());
			lineBuffer.setLength(0);
		    }
		    prevline = line;
		}
	    } while (line != null && line.length()  > 0);
	} catch (IOException ioex) {
	    throw new MessagingException("Error in input stream", ioex);
	}
}

Read and parse the given RFC822 message stream till the blank line separating the header from the body. Store the header lines inside this InternetHeaders object. The order of header lines is preserved.

Note that the header lines are added into this InternetHeaders object, so any existing headers in this object will not be affected. Headers are added to the end of the existing list of headers, in order.

 public  void removeHeader(String name) 
{
 
	for (int i = 0; i <  headers.size(); i++) {
	    InternetHeader h = (InternetHeader)headers.get(i);
	    if (name.equalsIgnoreCase(h.getName())) {
		h.line = null;
		//headers.remove(i);
		//i--;    // have to look at i again
	    }
	}
}

Remove all header entries that match the given name

 public  void setHeader(String name,
    String value) 
{
	boolean found = false;
	for (int i = 0; i <  headers.size(); i++) {
	    InternetHeader h = (InternetHeader)headers.get(i);
	    if (name.equalsIgnoreCase(h.getName())) {
		if (!found) {
		    int j;
		    if (h.line != null && (j = h.line.indexOf(':'))  >= 0) {
			h.line = h.line.substring(0, j + 1) + " " + value;
			// preserves capitalization, spacing
		    } else {
			h.line = name + ": " + value;
		    }
		    found = true;
		} else {
		    headers.remove(i);
		    i--;    // have to look at i again
		}
	    }
	}
	if (!found) {
	    addHeader(name, value);
	}
}

Change the first header line that matches name to have value, adding a new header if no existing header matches. Remove all matching headers but the first.

Note that RFC822 headers can only contain US-ASCII characters