| java.lang.Object de.ug2t.extTools.httpFileUpLoad.MultipartStream
MultipartStream | public class MultipartStream (Code) | |
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 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 author: Martin Cooper author: Sean C. Sullivan version: $Id: MultipartStream.java,v 1.12 2003/06/01 00:18:13 martinc Exp $ |
Inner Class :public class MalformedStreamException extends IOException | |
Inner Class :public class IllegalBoundaryException extends IOException | |
Field Summary | |
final protected static int | DEFAULT_BUFSIZE The default length of the buffer used for processing a request. | final protected static byte[] | FIELD_SEPARATOR A byte sequence that that follows a delimiter that will be followed by an
encapsulation (CRLF ). | final public static int | HEADER_PART_SIZE_MAX The maximum length of header-part that will be processed (10
kilobytes = 10240 bytes.). | final protected static byte[] | HEADER_SEPARATOR A byte sequence that marks the end of header-part (CRLFCRLF ). | final protected static byte[] | STREAM_TERMINATOR A byte sequence that that follows a delimiter of the last encapsulation in
the stream (-- ). |
Constructor Summary | |
public | MultipartStream() Default constructor. | public | 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. | public | MultipartStream(InputStream input, byte[] boundary)
Constructs a MultipartStream with a default size buffer. |
Method Summary | |
public static boolean | arrayequals(byte[] a, byte[] b, int count) Compares count first bytes in the arrays a
and b .
Parameters: a - The first array to compare. Parameters: b - The second array to compare. Parameters: count - How many bytes should be compared. | public 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 .
Parameters: value - The value to find. Parameters: pos - The starting position for searching. | protected int | findSeparator() Searches for the boundary in the buffer
region delimited by head and tail . | public String | getHeaderEncoding() Retrieves the character encoding used when reading the headers of an
individual part. | public int | readBodyData(OutputStream output)
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. | public boolean | readBoundary() Skips a boundary token, and checks whether more
encapsulations are contained in the stream. | public byte | readByte() Reads a byte from the buffer , and refills it as necessary. | public String | readHeaders()
Reads the header-part of the current
encapsulation .
Headers are returned verbatim to the input stream, including the trailing
CRLF marker. | public void | setBoundary(byte[] boundary)
Changes the boundary token used for partitioning the stream. | public void | setHeaderEncoding(String encoding) Specifies the character encoding to be used when reading the headers of
individual parts. | public boolean | skipPreamble() Finds the beginning of the first encapsulation . | public String | toString() Returns a string representation of this object. |
DEFAULT_BUFSIZE | final protected static int DEFAULT_BUFSIZE(Code) | | The default length of the buffer used for processing a request.
|
FIELD_SEPARATOR | final protected static byte[] FIELD_SEPARATOR(Code) | | A byte sequence that that follows a delimiter that will be followed by an
encapsulation (CRLF ).
|
HEADER_PART_SIZE_MAX | final public static int HEADER_PART_SIZE_MAX(Code) | | The maximum length of header-part that will be processed (10
kilobytes = 10240 bytes.).
|
HEADER_SEPARATOR | final protected static byte[] HEADER_SEPARATOR(Code) | | A byte sequence that marks the end of header-part (CRLFCRLF ).
|
STREAM_TERMINATOR | final protected static byte[] STREAM_TERMINATOR(Code) | | A byte sequence that that follows a delimiter of the last encapsulation in
the stream (-- ).
|
MultipartStream | public MultipartStream(InputStream input, byte[] boundary, int bufSize)(Code) | |
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[]) |
arrayequals | public static boolean arrayequals(byte[] a, byte[] b, int count)(Code) | | Compares count first bytes in the arrays a
and b .
Parameters: a - The first array to compare. Parameters: b - The second array to compare. Parameters: count - How many bytes should be compared. true if count first bytes in arraysa and b are equal. |
discardBodyData | public int discardBodyData() throws MalformedStreamException, IOException(Code) | |
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. |
findByte | protected int findByte(byte value, int pos)(Code) | | Searches for a byte of specified value in the buffer ,
starting at the specified position .
Parameters: value - The value to find. Parameters: pos - The starting position for searching. The position of byte found, counting from beginning of thebuffer , or -1 if not found. |
findSeparator | protected int findSeparator()(Code) | | Searches for the boundary in the buffer
region delimited by head and tail .
The position of the boundary found, counting from the beginning ofthe buffer , or -1 if not found. |
getHeaderEncoding | public String getHeaderEncoding()(Code) | | Retrieves the character encoding used when reading the headers of an
individual part. When not specified, or null , the platform
default encoding is used.
The encoding used to read part headers. |
readBodyData | public int readBodyData(OutputStream output) throws MalformedStreamException, IOException(Code) | |
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. |
readBoundary | public boolean readBoundary() throws MalformedStreamException(Code) | | Skips a boundary token, and checks whether more
encapsulations are contained in the stream.
true if there are more encapsulations in thisstream; false otherwise. exception: MalformedStreamException - if the stream ends unexpecetedly or fails to follow requiredsyntax. |
readByte | public byte readByte() throws IOException(Code) | | Reads a byte from the buffer , and refills it as necessary.
The next byte from the input stream. exception: IOException - if there is no more data available. |
readHeaders | public String readHeaders() throws MalformedStreamException(Code) | |
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. |
setBoundary | public void setBoundary(byte[] boundary) throws IllegalBoundaryException(Code) | |
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. exception: IllegalBoundaryException - if the boundary has a different length than theone being currently parsed. |
setHeaderEncoding | public void setHeaderEncoding(String encoding)(Code) | | 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. |
skipPreamble | public boolean skipPreamble() throws IOException(Code) | | Finds the beginning of the first encapsulation .
true if an encapsulation was found inthe stream. exception: IOException - if an i/o error occurs. |
toString | public String toString()(Code) | | Returns a string representation of this object.
The string representation of this object. |
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