org.apache.commons.fileupload.MultipartStream Class Reference

List of all members.


Detailed Description

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 setBoundary(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
    }

 

Author:
Rafal Krzewski

Martin Cooper

Sean C. Sullivan

Version:
Id
MultipartStream.java,v 1.12 2003/06/01 00:18:13 martinc Exp

Definition at line 134 of file MultipartStream.java.


Public Member Functions

 MultipartStream ()
 Default constructor.
 MultipartStream (InputStream input, byte[] boundary, int bufSize)
 MultipartStream (InputStream input, byte[] boundary) throws IOException
String getHeaderEncoding ()
 Retrieves the character encoding used when reading the headers of an individual part.
void setHeaderEncoding (String encoding)
 Specifies the character encoding to be used when reading the headers of individual parts.
byte readByte () throws IOException
 Reads a byte from the buffer, and refills it as necessary.
boolean readBoundary () throws MalformedStreamException
 Skips a boundary token, and checks whether more encapsulations are contained in the stream.
void setBoundary (byte[] boundary) throws IllegalBoundaryException
String readHeaders () throws MalformedStreamException
int readBodyData (OutputStream output) throws MalformedStreamException, IOException
int discardBodyData () throws MalformedStreamException, IOException
boolean skipPreamble () throws IOException
 Finds the beginning of the first encapsulation.
String toString ()
 Returns a string representation of this object.

Static Public Member Functions

static boolean arrayequals (byte[] a, byte[] b, int count)
 Compares count first bytes in the arrays a and b.

Static Public Attributes

static final int HEADER_PART_SIZE_MAX = 10240
 The maximum length of header-part that will be processed (10 kilobytes = 10240 bytes.

Protected Member Functions

int findByte (byte value, int pos)
 Searches for a byte of specified value in the buffer, starting at the specified position.
int findSeparator ()
 Searches for the boundary in the buffer region delimited by head and tail.

Static Protected Attributes

static final int DEFAULT_BUFSIZE = 4096
 The default length of the buffer used for processing a request.
static final byte[] HEADER_SEPARATOR = {0x0D, 0x0A, 0x0D, 0x0A}
 A byte sequence that marks the end of header-part (CRLFCRLF).
static final byte[] FIELD_SEPARATOR = { 0x0D, 0x0A }
 A byte sequence that that follows a delimiter that will be followed by an encapsulation (CRLF).
static final byte[] STREAM_TERMINATOR = { 0x2D, 0x2D }
 A byte sequence that that follows a delimiter of the last encapsulation in the stream (--).

Classes

class  IllegalBoundaryException
 Thrown upon attempt of setting an invalid boundary token. More...
class  MalformedStreamException
 Thrown to indicate that the input stream fails to follow the required syntax. More...

Constructor & Destructor Documentation

org.apache.commons.fileupload.MultipartStream.MultipartStream (  ) 

Default constructor.

See also:
MultipartStream(InputStream, byte[], int)

MultipartStream(InputStream, byte[])

Definition at line 246 of file MultipartStream.java.

org.apache.commons.fileupload.MultipartStream.MultipartStream ( InputStream  input,
byte[]  boundary,
int  bufSize 
)

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()

MultipartStream(InputStream, byte[])

Definition at line 269 of file MultipartStream.java.

org.apache.commons.fileupload.MultipartStream.MultipartStream ( InputStream  input,
byte[]  boundary 
) throws IOException

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.
Exceptions:
IOException when an error occurs.
See also:
MultipartStream()

MultipartStream(InputStream, byte[], int)

Definition at line 306 of file MultipartStream.java.

References org.apache.commons.fileupload.MultipartStream.DEFAULT_BUFSIZE.


Member Function Documentation

String org.apache.commons.fileupload.MultipartStream.getHeaderEncoding (  ) 

Retrieves the character encoding used when reading the headers of an individual part.

When not specified, or null, the platform default encoding is used.

Returns:
The encoding used to read part headers.

Definition at line 325 of file MultipartStream.java.

void org.apache.commons.fileupload.MultipartStream.setHeaderEncoding ( String  encoding  ) 

Specifies the character encoding to be used when reading the headers of individual parts.

When not specified, or null, the platform default encoding is used.

Parameters:
encoding The encoding used to read part headers.

Definition at line 338 of file MultipartStream.java.

Referenced by org.apache.commons.fileupload.FileUploadBase.parseRequest().

byte org.apache.commons.fileupload.MultipartStream.readByte (  )  throws IOException

Reads a byte from the buffer, and refills it as necessary.

Returns:
The next byte from the input stream.
Exceptions:
IOException if there is no more data available.

Definition at line 352 of file MultipartStream.java.

Referenced by org.apache.commons.fileupload.MultipartStream.readBoundary(), and org.apache.commons.fileupload.MultipartStream.readHeaders().

boolean org.apache.commons.fileupload.MultipartStream.readBoundary (  )  throws MalformedStreamException

Skips a boundary token, and checks whether more encapsulations are contained in the stream.

Returns:
true if there are more encapsulations in this stream; false otherwise.
Exceptions:
MalformedStreamException if the stream ends unexpecetedly or fails to follow required syntax.

Definition at line 381 of file MultipartStream.java.

References org.apache.commons.fileupload.MultipartStream.arrayequals(), org.apache.commons.fileupload.MultipartStream.FIELD_SEPARATOR, org.apache.commons.fileupload.MultipartStream.readByte(), and org.apache.commons.fileupload.MultipartStream.STREAM_TERMINATOR.

Referenced by org.apache.commons.fileupload.FileUploadBase.parseRequest(), and org.apache.commons.fileupload.MultipartStream.skipPreamble().

void org.apache.commons.fileupload.MultipartStream.setBoundary ( byte[]  boundary  )  throws IllegalBoundaryException

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.
Exceptions:
IllegalBoundaryException if the boundary has a different length than the one being currently parsed.

Definition at line 433 of file MultipartStream.java.

Referenced by org.apache.commons.fileupload.FileUploadBase.parseRequest().

String org.apache.commons.fileupload.MultipartStream.readHeaders (  )  throws MalformedStreamException

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.
Exceptions:
MalformedStreamException if the stream ends unexpecetedly.

Definition at line 460 of file MultipartStream.java.

References org.apache.commons.fileupload.MultipartStream.HEADER_PART_SIZE_MAX, org.apache.commons.fileupload.MultipartStream.HEADER_SEPARATOR, and org.apache.commons.fileupload.MultipartStream.readByte().

Referenced by org.apache.commons.fileupload.FileUploadBase.parseRequest().

int org.apache.commons.fileupload.MultipartStream.readBodyData ( OutputStream  output  )  throws MalformedStreamException, IOException

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 constructor).

Parameters:
output The Stream to write data into.
Returns:
the amount of data written.
Exceptions:
MalformedStreamException if the stream ends unexpectedly.
IOException if an i/o error occurs.

Definition at line 533 of file MultipartStream.java.

References org.apache.commons.fileupload.MultipartStream.findSeparator().

Referenced by org.apache.commons.fileupload.FileUploadBase.parseRequest().

int org.apache.commons.fileupload.MultipartStream.discardBodyData (  )  throws MalformedStreamException, IOException

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.
Exceptions:
MalformedStreamException if the stream ends unexpectedly.
IOException if an i/o error occurs.

Definition at line 612 of file MultipartStream.java.

References org.apache.commons.fileupload.MultipartStream.findSeparator().

Referenced by org.apache.commons.fileupload.FileUploadBase.parseRequest(), and org.apache.commons.fileupload.MultipartStream.skipPreamble().

boolean org.apache.commons.fileupload.MultipartStream.skipPreamble (  )  throws IOException

Finds the beginning of the first encapsulation.

Returns:
true if an encapsulation was found in the stream.
Exceptions:
IOException if an i/o error occurs.

Definition at line 681 of file MultipartStream.java.

References org.apache.commons.fileupload.MultipartStream.discardBodyData(), and org.apache.commons.fileupload.MultipartStream.readBoundary().

Referenced by org.apache.commons.fileupload.FileUploadBase.parseRequest().

static boolean org.apache.commons.fileupload.MultipartStream.arrayequals ( byte[]  a,
byte[]  b,
int  count 
) [static]

Compares 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.

Definition at line 722 of file MultipartStream.java.

Referenced by org.apache.commons.fileupload.MultipartStream.readBoundary().

int org.apache.commons.fileupload.MultipartStream.findByte ( byte  value,
int  pos 
) [protected]

Searches for a byte of specified value in the 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.

Definition at line 747 of file MultipartStream.java.

Referenced by org.apache.commons.fileupload.MultipartStream.findSeparator().

int org.apache.commons.fileupload.MultipartStream.findSeparator (  )  [protected]

Searches for the 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.

Definition at line 770 of file MultipartStream.java.

References org.apache.commons.fileupload.MultipartStream.findByte().

Referenced by org.apache.commons.fileupload.MultipartStream.discardBodyData(), and org.apache.commons.fileupload.MultipartStream.readBodyData().

String org.apache.commons.fileupload.MultipartStream.toString (  ) 

Returns a string representation of this object.

Returns:
The string representation of this object.

Definition at line 804 of file MultipartStream.java.


Member Data Documentation

final int org.apache.commons.fileupload.MultipartStream.HEADER_PART_SIZE_MAX = 10240 [static]

The maximum length of header-part that will be processed (10 kilobytes = 10240 bytes.

).

Definition at line 144 of file MultipartStream.java.

Referenced by org.apache.commons.fileupload.MultipartStream.readHeaders().


The documentation for this class was generated from the following file:
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