API java : InternetHeaders

javax.mail.internet
Class InternetHeaders

java.lang.Object
  javax.mail.internet.InternetHeaders

public class InternetHeaders
extends Object

InternetHeaders is a utility class that manages RFC822 style headers. Given an RFC822 format message stream, it reads lines until the blank line that indicates end of header. The input stream is positioned at the start of the body. The lines are stored within the object and can be extracted as either Strings or Header objects.

This class is mostly intended for service providers. MimeMessage and MimeBody use this class for holding their headers.

A note on RFC822 and MIME headers

RFC822 and MIME header fields must contain only US-ASCII characters. If a header contains non US-ASCII characters, it must be encoded as per the rules in RFC 2047. The MimeUtility class provided in this package can be used to to achieve this. Callers of the setHeader, addHeader, and addHeaderLine methods are responsible for enforcing the MIME requirements for the specified headers. In addition, these header fields must be folded (wrapped) before being sent if they exceed the line length limitation for the transport (1000 bytes for SMTP). Received headers may have been folded. The application is responsible for folding and unfolding headers as appropriate.

Author:

John Mani, Bill Shannon

See Also:

MimeUtility

Nested Class Summary
protected static class	InternetHeaders.InternetHeader           An individual internet header.

 

Field Summary
protected  List	headers           The actual list of Headers, including placeholder entries.

 

Constructor Summary
InternetHeaders()           Create an empty InternetHeaders object.
InternetHeaders(InputStream is)           Read and parse the given RFC822 message stream till the blank line separating the header from the body.

 

Method Summary
void	addHeader(String name, String value)           Add a header with the specified name and value to the header list.
void	addHeaderLine(String line)           Add an RFC822 header line to the header store.
Enumeration	getAllHeaderLines()           Return all the header lines as an Enumeration of Strings.
Enumeration	getAllHeaders()           Return all the headers as an Enumeration of Header objects.
String[]	getHeader(String name)           Return all the values for the specified header.
String	getHeader(String name, String delimiter)           Get all the headers for this header name, returned as a single String, with headers separated by the delimiter.
Enumeration	getMatchingHeaderLines(String[] names)           Return all matching header lines as an Enumeration of Strings.
Enumeration	getMatchingHeaders(String[] names)           Return all matching Header objects.
Enumeration	getNonMatchingHeaderLines(String[] names)           Return all non-matching header lines
Enumeration	getNonMatchingHeaders(String[] names)           Return all non-matching Header objects.
void	load(InputStream is)           Read and parse the given RFC822 message stream till the blank line separating the header from the body.
void	removeHeader(String name)           Remove all header entries that match the given name
void	setHeader(String name, String value)           Change the first header line that matches name to have value, adding a new header if no existing header matches.

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

headers

protected List headers

The actual list of Headers, including placeholder entries. Placeholder entries are Headers with a null value and are never seen by clients of the InternetHeaders class. Placeholder entries are used to keep track of the preferred order of headers. Headers are never actually removed from the list, they're converted into placeholder entries. New headers are added after existing headers of the same name (or before in the case of Received and Return-Path headers). If no existing header or placeholder for the header is found, new headers are added after the special placeholder with the name ":".

Since:

JavaMail 1.4

InternetHeaders

public InternetHeaders()

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

InternetHeaders

public InternetHeaders(InputStream is)
                throws MessagingException

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

Throws:

MessagingException

load

public void load(InputStream is)
          throws MessagingException

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.

Parameters:

is - RFC822 input stream

Throws:

MessagingException

getHeader

public String[] getHeader(String name)

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

Parameters:

name - header name

Returns:

array of header values, or null if none

getHeader

public String getHeader(String name,
                        String delimiter)

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.

Parameters:

name - header name

delimiter - delimiter

Returns:

the value fields for all headers with this name, or null if none

setHeader

public void setHeader(String name,
                      String 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

Parameters:

name - header name

value - header value

addHeader

public void addHeader(String name,
                      String 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.

Parameters:

name - header name

value - header value

removeHeader

public void removeHeader(String name)

Remove all header entries that match the given name

Parameters:

name - header name

getAllHeaders

public Enumeration getAllHeaders()

Return all the headers as an Enumeration of Header objects.

Returns:

Header objects

getMatchingHeaders

public Enumeration getMatchingHeaders(String[] names)

Return all matching Header objects.

Returns:

matching Header objects

getNonMatchingHeaders

public Enumeration getNonMatchingHeaders(String[] names)

Return all non-matching Header objects.

Returns:

non-matching Header objects

addHeaderLine

public void addHeaderLine(String line)

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

Parameters:

line - raw RFC822 header line

getAllHeaderLines

public Enumeration getAllHeaderLines()

Return all the header lines as an Enumeration of Strings.

getMatchingHeaderLines

public Enumeration getMatchingHeaderLines(String[] names)

Return all matching header lines as an Enumeration of Strings.

getNonMatchingHeaderLines

public Enumeration getNonMatchingHeaderLines(String[] names)

Return all non-matching header lines