org.apache.tomcat.util.http.fileupload
public class MultipartStream extends Object
Low level API for processing file uploads.
This class can be used to process data streams conforming to MIME 'multipart' format as defined in RFC 1867. Arbitrarily large amounts of data in the stream can be processed under constant memory usage.
The format of the stream is defined in the following way:
multipart-body := preamble 1*encapsulation close-delimiter epilogue
encapsulation := delimiter body CRLF
delimiter := "--" boundary CRLF
close-delimiter := "--" boudary "--"
preamble := <ignore>
epilogue := <ignore>
body := header-part CRLF body-part
header-part := 1*header CRLF
header := header-name ":" header-value
header-name := <printable ascii characters except ":">
header-value := <any ascii characters except CR & LF>
body-data := <arbitrary data>
Note that body-data can contain another mulipart entity. There
is limited support for single pass processing of such nested
streams. The nested stream is required to have a
boundary token of the same length as the parent stream (see (byte[])
).
Here is an exaple of usage of this class.
try { MultipartStream multipartStream = new MultipartStream(input, boundary); boolean nextPart = malitPartStream.skipPreamble(); OutputStream output; while(nextPart) { header = chunks.readHeader(); // process headers // create some output stream multipartStream.readBodyPart(output); nextPart = multipartStream.readBoundary(); } } catch(MultipartStream.MalformedStreamException e) { // the stream failed to follow required syntax } catch(IOException) { // a read or write error occurred }
Version: $Id: MultipartStream.java 467222 2006-10-24 03:17:11Z markt $
Nested Class Summary | |
---|---|
class | MultipartStream.IllegalBoundaryException
Thrown upon attempt of setting an invalid boundary token. |
class | MultipartStream.MalformedStreamException
Thrown to indicate that the input stream fails to follow the
required syntax. |
Field Summary | |
---|---|
protected static int | DEFAULT_BUFSIZE
The default length of the buffer used for processing a request. |
protected static byte[] | FIELD_SEPARATOR
A byte sequence that that follows a delimiter that will be
followed by an encapsulation ( CRLF ). |
static int | HEADER_PART_SIZE_MAX
The maximum length of header-part that will be
processed (10 kilobytes = 10240 bytes.). |
protected static byte[] | HEADER_SEPARATOR
A byte sequence that marks the end of header-part
(CRLFCRLF ). |
protected static byte[] | STREAM_TERMINATOR
A byte sequence that that follows a delimiter of the last
encapsulation in the stream ( -- ). |
Constructor Summary | |
---|---|
MultipartStream()
Default constructor.
| |
MultipartStream(InputStream input, byte[] boundary, int bufSize) Constructs a | |
MultipartStream(InputStream input, byte[] boundary) Constructs a |
Method Summary | |
---|---|
static boolean | arrayequals(byte[] a, byte[] b, int count)
Compares count first bytes in the arrays
a and b .
|
int | discardBodyData() Reads |
protected int | findByte(byte value, int pos)
Searches for a byte of specified value in the buffer ,
starting at the specified position .
|
protected int | findSeparator()
Searches for the boundary in the buffer
region delimited by head and tail .
|
String | getHeaderEncoding()
Retrieves the character encoding used when reading the headers of an
individual part. |
int | readBodyData(OutputStream output) Reads |
boolean | readBoundary()
Skips a boundary token, and checks whether more
encapsulations are contained in the stream.
|
byte | readByte()
Reads a byte from the buffer , and refills it as
necessary.
|
String | readHeaders() Reads the |
void | setBoundary(byte[] boundary) Changes the boundary token used for partitioning the stream. |
void | setHeaderEncoding(String encoding)
Specifies the character encoding to be used when reading the headers of
individual parts. |
boolean | skipPreamble()
Finds the beginning of the first encapsulation .
|
String | toString()
Returns a string representation of this object.
|
CRLF
).header-part
that will be
processed (10 kilobytes = 10240 bytes.).header-part
(CRLFCRLF
).--
). Constructs a MultipartStream
with a custom size buffer.
Note that the buffer must be at least big enough to contain the boundary string, plus 4 characters for CR/LF and double dash, plus at least one byte of data. Too small a buffer size setting will degrade performance.
Parameters: input The InputStream
to serve as a data source. boundary The token used for dividing the stream into
encapsulations
. bufSize The size of the buffer to be used, in bytes.
See Also: MultipartStream (InputStream, byte[])
Constructs a MultipartStream
with a default size buffer.
Parameters: input The InputStream
to serve as a data source. boundary The token used for dividing the stream into
encapsulations
.
Throws: IOException when an error occurs.
See Also: MultipartStream (InputStream, byte[], int)
count
first bytes in the arrays
a
and b
.
Parameters: a The first array to compare. b The second array to compare. count How many bytes should be compared.
Returns: true
if count
first bytes in arrays
a
and b
are equal.
Reads body-data
from the current
encapsulation
and discards it.
Use this method to skip encapsulations you don't need or don't understand.
Returns: The amount of data discarded.
Throws: MalformedStreamException if the stream ends unexpectedly. IOException if an i/o error occurs.
buffer
,
starting at the specified position
.
Parameters: value The value to find. pos The starting position for searching.
Returns: The position of byte found, counting from beginning of the
buffer
, or -1
if not found.
boundary
in the buffer
region delimited by head
and tail
.
Returns: The position of the boundary found, counting from the
beginning of the buffer
, or -1
if
not found.
null
, the platform
default encoding is used.
Returns: The encoding used to read part headers.
Reads body-data
from the current
encapsulation
and writes its contents into the
output Stream
.
Arbitrary large amounts of data can be processed by this
method using a constant size buffer. (see (InputStream,byte[],int) constructor
).
Parameters: output The Stream
to write data into.
Returns: the amount of data written.
Throws: MalformedStreamException if the stream ends unexpectedly. IOException if an i/o error occurs.
boundary
token, and checks whether more
encapsulations
are contained in the stream.
Returns: true
if there are more encapsulations in
this stream; false
otherwise.
Throws: MalformedStreamException if the stream ends unexpecetedly or fails to follow required syntax.
buffer
, and refills it as
necessary.
Returns: The next byte from the input stream.
Throws: IOException if there is no more data available.
Reads the header-part
of the current
encapsulation
.
Headers are returned verbatim to the input stream, including the
trailing CRLF
marker. Parsing is left to the
application.
TODO allow limiting maximum header size to protect against abuse.
Returns: The header-part
of the current encapsulation.
Throws: MalformedStreamException if the stream ends unexpecetedly.
Changes the boundary token used for partitioning the stream.
This method allows single pass processing of nested multipart streams.
The boundary token of the nested stream is required
to be of the same length as the boundary token in parent stream.
Restoring the parent stream boundary token after processing of a nested stream is left to the application.
Parameters: boundary The boundary to be used for parsing of the nested stream.
Throws: IllegalBoundaryException if the boundary
has a different length than the one
being currently parsed.
null
, the platform
default encoding is used.
Parameters: encoding The encoding used to read part headers.
encapsulation
.
Returns: true
if an encapsulation
was found in
the stream.
Throws: IOException if an i/o error occurs.
Returns: The string representation of this object.