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java.lang.Object wicket.util.upload.MultipartFormInputStream
public class MultipartFormInputStream
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 }
Nested Class Summary | |
---|---|
class |
MultipartFormInputStream.IllegalBoundaryException
Thrown upon attempt of setting an invalid boundary token. |
class |
MultipartFormInputStream.MalformedStreamException
Thrown to indicate that the input stream fails to follow the required syntax. |
Field Summary | |
---|---|
static byte |
CR
The Carriage Return ASCII character value. |
static byte |
DASH
The dash (-) ASCII character value. |
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 ). |
static byte |
LF
The Line Feed ASCII character value. |
protected static byte[] |
STREAM_TERMINATOR
A byte sequence that that follows a delimiter of the last encapsulation in the stream ( -- ). |
Constructor Summary | |
---|---|
MultipartFormInputStream()
Default constructor. |
|
MultipartFormInputStream(java.io.InputStream input,
byte[] boundary)
Constructs a MultipartStream with a default size buffer. |
|
MultipartFormInputStream(java.io.InputStream input,
byte[] boundary,
int bufSize)
Constructs a MultipartStream with a custom size buffer. |
Method Summary | |
---|---|
static boolean |
arrayequals(byte[] a,
byte[] b,
int count)
Compares count first bytes in the arrays a
and b . |
int |
discardBodyData()
Reads body-data from the current
encapsulation and discards it. |
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 . |
java.lang.String |
getHeaderEncoding()
Retrieves the character encoding used when reading the headers of an individual part. |
int |
readBodyData(java.io.OutputStream output)
Reads body-data from the current
encapsulation and writes its contents into the output
Stream . |
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. |
java.lang.String |
readHeaders(int maxSize)
Reads the header-part of the current
encapsulation . |
void |
setBoundary(byte[] boundary)
Changes the boundary token used for partitioning the stream. |
void |
setHeaderEncoding(java.lang.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 . |
java.lang.String |
toString()
Returns a string representation of this object. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
---|
public static final byte CR
public static final byte LF
public static final byte DASH
public static final int HEADER_PART_SIZE_MAX
header-part
that will be processed
(10 kilobytes = 10240 bytes.).
protected static final int DEFAULT_BUFSIZE
protected static final byte[] HEADER_SEPARATOR
header-part
(CRLFCRLF
).
protected static final byte[] FIELD_SEPARATOR
CRLF
).
protected static final byte[] STREAM_TERMINATOR
--
).
Constructor Detail |
---|
public MultipartFormInputStream()
MultipartFormInputStream(InputStream, byte[], int)
,
MultipartFormInputStream(InputStream, byte[])
public MultipartFormInputStream(java.io.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.
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.MultipartFormInputStream()
,
MultipartFormInputStream(InputStream, byte[])
public MultipartFormInputStream(java.io.InputStream input, byte[] boundary)
Constructs a MultipartStream
with a default size buffer.
input
- The InputStream
to serve as a data source.boundary
- The token used for dividing the stream into
encapsulations
.MultipartFormInputStream()
,
MultipartFormInputStream(InputStream, byte[], int)
Method Detail |
---|
public java.lang.String getHeaderEncoding()
null
, the
platform default encoding is used.
public void setHeaderEncoding(java.lang.String encoding)
null
, the
platform default encoding is used.
encoding
- The encoding used to read part headers.public byte readByte() throws java.io.IOException
buffer
, and refills it as
necessary.
java.io.IOException
- if there is no more data available.public boolean readBoundary() throws MultipartFormInputStream.MalformedStreamException
boundary
token, and checks whether more
encapsulations
are contained in the stream.
true
if there are more encapsulations in this
stream; false
otherwise.
MultipartFormInputStream.MalformedStreamException
- if the stream ends unexpecetedly or fails to follow
required syntax.public void setBoundary(byte[] boundary) throws MultipartFormInputStream.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.
boundary
- The boundary to be used for parsing of the nested stream.
MultipartFormInputStream.IllegalBoundaryException
- if the boundary
has a different length than
the one being currently parsed.public java.lang.String readHeaders(int maxSize) throws MultipartFormInputStream.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.
maxSize
- The maximum amount to read before giving up
header-part
of the current encapsulation.
MultipartFormInputStream.MalformedStreamException
- if the stream ends unexpecetedly.public int readBodyData(java.io.OutputStream output) throws MultipartFormInputStream.MalformedStreamException, java.io.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
).
output
- The Stream
to write data into.
MultipartFormInputStream.MalformedStreamException
- if the stream ends unexpectedly.
java.io.IOException
- if an i/o error occurs.public int discardBodyData() throws MultipartFormInputStream.MalformedStreamException, java.io.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.
MultipartFormInputStream.MalformedStreamException
- if the stream ends unexpectedly.
java.io.IOException
- if an i/o error occurs.public boolean skipPreamble() throws java.io.IOException
encapsulation
.
true
if an encapsulation
was found
in the stream.
java.io.IOException
- if an i/o error occurs.public static boolean arrayequals(byte[] a, byte[] b, int count)
count
first bytes in the arrays a
and b
.
a
- The first array to compare.b
- The second array to compare.count
- How many bytes should be compared.
true
if count
first bytes in arrays
a
and b
are equal.protected int findByte(byte value, int pos)
buffer
,
starting at the specified position
.
value
- The value to find.pos
- The starting position for searching.
buffer
, or -1
if not found.protected int findSeparator()
boundary
in the buffer
region delimited by head
and tail
.
buffer
, or -1
if not found.public java.lang.String toString()
toString
in class java.lang.Object
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