Java Doc for MultipartStream.java in  » Forum » JForum-2.1.8 » net » jforum » util » legacy » commons » fileupload » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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 MultipartStream.setBoundary(byte[]) ).

Here is an example of usage of this class.

 try {
 MultipartStream multipartStream = new MultipartStream(input,
 boundary);
 boolean nextPart = multipartStream.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
 }
 

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.

Constructs a MultipartStream with a default size buffer.

Reads body-data from the current encapsulation and discards it.

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.

Reads the header-part of the current encapsulation.

Headers are returned verbatim to the input stream, including the trailing CRLF marker.

Changes the boundary token used for partitioning the stream.

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.
Parameters:
  boundary - The token used for dividing the stream intoencapsulations.
Parameters:
  bufSize - The size of the buffer to be used, in bytes.
See Also:   MultipartStream.MultipartStream()
See Also:   MultipartStream.MultipartStream(InputStream,byte[])

Constructs a MultipartStream with a default size buffer.
Parameters:
  input - The InputStream to serve as a data source.
Parameters:
  boundary - The token used for dividing the stream intoencapsulations.
exception:
  IOException - when an error occurs.
See Also:   MultipartStream.MultipartStream()
See Also:   MultipartStream.MultipartStream(InputStream,byte[],int)

Reads body-data from the current encapsulation and discards it.

Use this method to skip encapsulations you don't need or don't understand. The amount of data discarded.
exception:
  MalformedStreamException - if the stream ends unexpectedly.
exception:
  IOException - if an i/o error occurs.

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 MultipartStream.MultipartStream(InputStream,byte[],int) constructor ).
Parameters:
  output - The Stream to write data into. the amount of data written.
exception:
  MalformedStreamException - if the stream ends unexpectedly.
exception:
  IOException - if an i/o error occurs.

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. The header-part of the current encapsulation.
exception:
  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 nestedstream.
exception:
  IllegalBoundaryException - if the boundaryhas a different length than the onebeing currently parsed.