MultipartStream (Apache Tomcat 7.0.109 API Documentation)

java.lang.Object
- org.apache.tomcat.util.http.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 := "--" boundary "--" 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) {
       String header = multipartStream.readHeaders();
       // process headers
       // create some output stream
       multipartStream.readBodyData(output);
       nextPart = multipartStream.readBoundary();
     }
   } catch(MultipartStream.MalformedStreamException e) {
     // the stream failed to follow required syntax
   } catch(IOException e) {
     // a read or write error occurred
   }
 
```

Nested Class Summary

Nested Classes
Modifier and Type	Class and 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.
`static class`	`MultipartStream.ProgressNotifier` Internal class, which is used to invoke the `ProgressListener`.

Field Summary

Fields
Modifier and Type	Field and Description
`protected static byte[]`	`BOUNDARY_PREFIX` A byte sequence that precedes a boundary (`CRLF--`).
`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

Constructors
Constructor and Description
`MultipartStream(InputStream input, byte[] boundary, int bufSize, MultipartStream.ProgressNotifier pNotifier)` Constructs a `MultipartStream` with a custom size buffer.
`MultipartStream(InputStream input, byte[] boundary, MultipartStream.ProgressNotifier pNotifier)` Constructs a `MultipartStream` with a default size buffer.

Method Summary

Methods
Modifier and Type	Method and 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.
`MultipartStream.ItemInputStream`	`newInputStream()` Creates a new `MultipartStream.ItemInputStream`.
`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
  - DEFAULT_BUFSIZE
```
protected static final int DEFAULT_BUFSIZE
```
    The default length of the buffer used for processing a request.
    
    See Also:
    Constant Field Values
  - HEADER_SEPARATOR
```
protected static final byte[] HEADER_SEPARATOR
```
    A byte sequence that marks the end of header-part (CRLFCRLF).
  - FIELD_SEPARATOR
```
protected static final byte[] FIELD_SEPARATOR
```
    A byte sequence that that follows a delimiter that will be followed by an encapsulation (CRLF).
  - STREAM_TERMINATOR
```
protected static final byte[] STREAM_TERMINATOR
```
    A byte sequence that that follows a delimiter of the last encapsulation in the stream (--).
  - BOUNDARY_PREFIX
```
protected static final byte[] BOUNDARY_PREFIX
```
    A byte sequence that precedes a boundary (CRLF--).
- Constructor Detail
  - MultipartStream
```
public MultipartStream(InputStream input,
               byte[] boundary,
               int bufSize,
               MultipartStream.ProgressNotifier pNotifier)
```
    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.
    pNotifier - The notifier, which is used for calling the progress listener, if any.
    
    Throws:
    
    IllegalArgumentException - If the buffer size is too small
    Since:
    
    1.3.1
  - MultipartStream
```
public MultipartStream(InputStream input,
               byte[] boundary,
               MultipartStream.ProgressNotifier pNotifier)
```
    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.
    pNotifier - An object for calling the progress listener, if any.
    See Also:
    MultipartStream(InputStream, byte[], int, ProgressNotifier)
- 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 FileUploadIOException,
                            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:
    
    FileUploadIOException - if the bytes read from the stream exceeded the size limits
    
    MultipartStream.MalformedStreamException - if the stream ends unexpectedly 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 FileUploadIOException,
                          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:
    
    FileUploadIOException - if the bytes read from the stream exceeded the size limits.
    
    MultipartStream.MalformedStreamException - if the stream ends unexpectedly.
  - 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.
  - newInputStream
```
public MultipartStream.ItemInputStream newInputStream()
```
    Creates a new MultipartStream.ItemInputStream.
    
    Returns:
    A new instance of MultipartStream.ItemInputStream.
  - 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

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

CR

LF

DASH

HEADER_PART_SIZE_MAX

DEFAULT_BUFSIZE

HEADER_SEPARATOR

FIELD_SEPARATOR

STREAM_TERMINATOR

BOUNDARY_PREFIX

Constructor Detail

MultipartStream

MultipartStream

Method Detail

getHeaderEncoding

setHeaderEncoding

readByte

readBoundary

setBoundary

readHeaders

readBodyData

newInputStream

discardBodyData

skipPreamble

arrayequals

findByte

findSeparator