java.lang.Object
- org.apache.catalina.fileupload.MultipartStream

```
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 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
    }

 
```
Version:

$Id: MultipartStream.java 607869 2008-01-01 16:42:17Z jochen $

Author:

Rafal Krzewski, Martin Cooper, Sean C. Sullivan

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`static class`	`MultipartStream.IllegalBoundaryException`	Thrown upon attempt of setting an invalid boundary token.
`class`	`MultipartStream.ItemInputStream`	An `InputStream` for reading an items contents.
`static class`	`MultipartStream.MalformedStreamException`	Thrown to indicate that the input stream fails to follow the required syntax.

Field Summary

Fields
Modifier and Type	Field	Description
`static byte`	`CR`	The Carriage Return ASCII character value.
`static byte`	`DASH`	The dash (-) ASCII character value.
`static int`	`HEADER_PART_SIZE_MAX`	The maximum length of `header-part` that will be processed (10 kilobytes = 10240 bytes.).
`static byte`	`LF`	The Line Feed ASCII character value.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`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`.
`String`	`getHeaderEncoding()`	Retrieves the character encoding used when reading the headers of an individual part.
`int`	`readBodyData(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.
`String`	`readHeaders()`	Reads the `header-part` of the current `encapsulation`.
`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`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - CR
```
public static final byte CR
```
    The Carriage Return ASCII character value.
    
    See Also:
    
    Constant Field Values
  - LF
```
public static final byte LF
```
    The Line Feed ASCII character value.
    
    See Also:
    
    Constant Field Values
  - DASH
```
public static final byte DASH
```
    The dash (-) ASCII character value.
    
    See Also:
    
    Constant Field Values
  - HEADER_PART_SIZE_MAX
```
public static final int HEADER_PART_SIZE_MAX
```
    The maximum length of header-part that will be processed (10 kilobytes = 10240 bytes.).
    
    See Also:
    
    Constant Field Values
- Method Detail
  - getHeaderEncoding
```
public String 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.
  - setHeaderEncoding
```
public void 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.
  - readByte
```
public byte readByte()
              throws IOException
```
    Reads a byte from the buffer, and refills it as necessary.
    
    Returns:
    
    The next byte from the input stream.
    
    Throws:
    
    IOException - if there is no more data available.
  - readBoundary
```
public boolean readBoundary()
                     throws MultipartStream.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.
    
    Throws:
    
    MultipartStream.MalformedStreamException - if the stream ends unexpecetedly or fails to follow required syntax.
  - setBoundary
```
public void setBoundary(byte[] boundary)
                 throws MultipartStream.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.
    
    Throws:
    
    MultipartStream.IllegalBoundaryException - if the boundary has a different length than the one being currently parsed.
  - readHeaders
```
public String readHeaders()
                   throws MultipartStream.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.
    
    Throws:
    
    MultipartStream.MalformedStreamException - if the stream ends unexpecetedly.
  - readBodyData
```
public int readBodyData(OutputStream output)
                 throws MultipartStream.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. May be null, in which case this method is equivalent to discardBodyData().
    
    Returns:
    
    the amount of data written.
    
    Throws:
    
    MultipartStream.MalformedStreamException - if the stream ends unexpectedly.
    
    IOException - if an i/o error occurs.
  - discardBodyData
```
public int discardBodyData()
                    throws MultipartStream.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.
    
    Throws:
    
    MultipartStream.MalformedStreamException - if the stream ends unexpectedly.
    
    IOException - if an i/o error occurs.
  - skipPreamble
```
public boolean skipPreamble()
                     throws IOException
```
    Finds the beginning of the first encapsulation.
    
    Returns:
    
    true if an encapsulation was found in the stream.
    
    Throws:
    
    IOException - if an i/o error occurs.
  - arrayequals
```
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.
    
    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.
  - findByte
```
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.
    
    pos - The starting position for searching.
    
    Returns:
    
    The position of byte found, counting from beginning of the buffer, or -1 if not found.
  - findSeparator
```
protected int findSeparator()
```
    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.

Class MultipartStream

Nested Class Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

CR

LF

DASH

HEADER_PART_SIZE_MAX

Method Detail

getHeaderEncoding

setHeaderEncoding

readByte

readBoundary

setBoundary

readHeaders

readBodyData

discardBodyData

skipPreamble

arrayequals

findByte

findSeparator