# Class ByteChunk

java.lang.Object
org.apache.tomcat.util.buf.AbstractChunk
org.apache.tomcat.util.buf.ByteChunk

All Implemented Interfaces:
  `Serializable, Cloneable`

public final class ByteChunk extends AbstractChunk
This class is used to represent a chunk of bytes, and utilities to manipulate byte[].

The buffer can be modified and used for both input and output.

There are 2 modes: The chunk can be associated with a sink - ByteInputChannel or ByteOutputChannel, which will be used when the buffer is empty (on input) or filled (on output). For output, it can also grow. This operating mode is selected by calling setLimit() or allocate(initial, limit) with limit != -1.

Various search and append method are defined - similar with String and StringBuffer, but operating on bytes.

This is important because it allows processing the http headers directly on the received bytes, without converting to chars and Strings until the strings are needed. In addition, the charset is determined later, from headers or user code.

In a server it is very important to be able to operate on the original byte[] without converting everything to chars. Some protocols are ASCII only, and some allow different non-UNICODE encodings. The encoding is not known beforehand, and can even change during the execution of the protocol. ( for example a multipart message may have parts with different encoding )

For HTTP, it is not very clear how the encoding of RequestURI and mime values can be determined, but it is a great advantage to be able to parse the request without converting to string.

See Also:
  - Serialized Form

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static class`
  `ByteChunk.BufferOverflowException`
  Exception thrown when a byte chunk buffer overflows.
  `static interface`
  `ByteChunk.ByteInputChannel`
  Input interface, used when the buffer is empty.
  `static interface`
  `ByteChunk.ByteOutputChannel`
  When we need more space we'll either grow the buffer ( up to the limit ) or send it to a channel.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final Charset`
  `DEFAULT_CHARSET`
  Default encoding used to convert to strings.

  ### Fields inherited from class AbstractChunk

  `ARRAY_MAX_SIZE, end, hasHashCode, isSet, sm, start`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ByteChunk()`
  Creates a new, uninitialized ByteChunk object.
  `ByteChunk(int initial)`
  Creates a ByteChunk with the specified initial buffer size.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `allocate(int initial, int limit)`
  Allocates a buffer with the specified initial size and optional limit.
  `void`
  `append(byte b)`
  Appends a single byte to this chunk.
  `void`
  `append(byte[] src, int off, int len)`
  Add data to the buffer.
  `void`
  `append(ByteBuffer from)`
  Add data to the buffer.
  `void`
  `append(ByteChunk src)`
  Appends the contents of another ByteChunk.
  `ByteChunk`
  `clone()`
  `static byte[]`
  `convertToBytes(String value)`
  Convert specified String to a byte array.
  `boolean`
  `equals(byte[] b2, int off2, int len2)`
  Compares this chunk to a byte array region.
  `boolean`
  `equals(char[] c2, int off2, int len2)`
  Compares the message bytes to the specified char array.
  `boolean`
  `equals(Object obj)`
  `boolean`
  `equals(String s)`
  Compares the message bytes to the specified String object.
  `boolean`
  `equals(ByteChunk bb)`
  Compares this chunk to another ByteChunk.
  `boolean`
  `equals(CharChunk cc)`
  Compares this chunk to a CharChunk.
  `boolean`
  `equalsIgnoreCase(byte[] b2, int off2, int len2)`
  Compares this chunk to a byte array region, ignoring case.
  `boolean`
  `equalsIgnoreCase(String s)`
  Compares the message bytes to the specified String object.
  `static int`
  `findByte(byte[] bytes, int start, int end, byte b)`
  Returns the first instance of the given byte in the byte array between the specified start and end.
  `static int`
  `findBytes(byte[] bytes, int start, int end, byte[] b)`
  Returns the first instance of the given bytes in the byte array between the specified start and end.
  `void`
  `flushBuffer()`
  Send the buffer to the sink.
  `byte[]`
  `getBuffer()`
  Returns the underlying byte array.
  `protected int`
  `getBufferElement(int index)`
  Returns the element at the specified index in the buffer.
  `byte[]`
  `getBytes()`
  Returns the underlying byte array.
  `Charset`
  `getCharset()`
  Returns the character set for this chunk.
  `long`
  `getLong()`
  Parses the byte chunk content as a long integer.
  `static int`
  `indexOf(byte[] bytes, int start, int end, char s)`
  Returns the first instance of the given character in the given byte array between the specified start and end.
  `int`
  `indexOf(char c, int starting)`
  Returns the first instance of the given character in this ByteChunk starting at the specified byte.
  `void`
  `makeSpace(int count)`
  Make space for len bytes.
  `void`
  `recycle()`
  Resets the chunk to an uninitialized state.
  `void`
  `setByteInputChannel(ByteChunk.ByteInputChannel in)`
  When the buffer is empty, read the data from the input channel.
  `void`
  `setByteOutputChannel(ByteChunk.ByteOutputChannel out)`
  When the buffer is full, write the data to the output channel.
  `void`
  `setBytes(byte[] b, int off, int len)`
  Sets the buffer to the specified sub array of bytes.
  `void`
  `setCharset(Charset charset)`
  Sets the character set for this chunk.
  `boolean`
  `startsWith(String s, int pos)`
  Returns true if the buffer starts with the specified string when tested in a case-sensitive manner.
  `boolean`
  `startsWithIgnoreCase(String s, int pos)`
  Returns true if the buffer starts with the specified string when tested in a case-insensitive manner.
  `int`
  `subtract()`
  Reads and removes the next byte from this chunk.
  `int`
  `subtract(byte[] dest, int off, int len)`
  Reads bytes into the specified array.
  `int`
  `subtract(ByteBuffer to)`
  Transfers bytes from the buffer to the specified ByteBuffer.
  `byte`
  `subtractB()`
  Deprecated.
  Use `subtract()` instead.
  `String`
  `toString()`
  `String`
  `toString(CodingErrorAction malformedInputAction, CodingErrorAction unmappableCharacterAction)`
  Converts the byte chunk to a String using the configured charset.
  `String`
  `toStringInternal(CodingErrorAction malformedInputAction, CodingErrorAction unmappableCharacterAction)`
  Converts the current content of the byte buffer to a String using the configured character set.

  ### Methods inherited from class AbstractChunk

  `getEnd, getLength, getLimit, getLimitInternal, getOffset, getStart, hash, hashCode, indexOf, isNull, setEnd, setLimit, setOffset, setStart`

  ### Methods inherited from class Object

  `finalize, getClass, notify, notifyAll, wait, wait, wait`

- ## Field Details

  - ### DEFAULT_CHARSET

    public static final Charset DEFAULT_CHARSET
    Default encoding used to convert to strings. It should be UTF8, as most standards seem to converge, but the servlet API requires 8859_1, and this object is used mostly for servlets.

- ## Constructor Details

  - ### ByteChunk

    public ByteChunk()
    Creates a new, uninitialized ByteChunk object.

  - ### ByteChunk

    public ByteChunk(int initial)
    Creates a ByteChunk with the specified initial buffer size.
    Parameters:
      `initial` - initial buffer size

- ## Method Details

  - ### clone

    public ByteChunk clone() throws CloneNotSupportedException
    Overrides:
      `clone` in class `Object`
    Throws:
      `CloneNotSupportedException`

  - ### recycle

    public void recycle()
    Description copied from class: `AbstractChunk`
    Resets the chunk to an uninitialized state.
    Overrides:
      `recycle` in class `AbstractChunk`

  - ### allocate

    public void allocate(int initial, int limit)
    Allocates a buffer with the specified initial size and optional limit.
    Parameters:
      `initial` - initial size
      `limit` - maximum size or -1 for unlimited

  - ### setBytes

    public void setBytes(byte[] b, int off, int len)
    Sets the buffer to the specified sub array of bytes.
    Parameters:
      `b` - the ascii bytes
      `off` - the start offset of the bytes
      `len` - the length of the bytes

  - ### setCharset

    public void setCharset(Charset charset)
    Sets the character set for this chunk.
    Parameters:
      `charset` - the character set

  - ### getCharset

    public Charset getCharset()
    Returns the character set for this chunk.
    Returns:
      the character set

  - ### getBytes

    public byte[] getBytes()
    Returns the underlying byte array.
    Returns:
      the buffer

  - ### getBuffer

    public byte[] getBuffer()
    Returns the underlying byte array.
    Returns:
      the buffer

  - ### setByteInputChannel

    public void setByteInputChannel(ByteChunk.ByteInputChannel in)
    When the buffer is empty, read the data from the input channel.
    Parameters:
      `in` - The input channel

  - ### setByteOutputChannel

    public void setByteOutputChannel(ByteChunk.ByteOutputChannel out)
    When the buffer is full, write the data to the output channel. Also used when large amount of data is appended. If not set, the buffer will grow to the limit.
    Parameters:
      `out` - The output channel

  - ### append

    public void append(byte b) throws IOException
    Appends a single byte to this chunk.
    Parameters:
      `b` - the byte to append
    Throws:
      `IOException` - if writing fails

  - ### append

    public void append(ByteChunk src) throws IOException
    Appends the contents of another ByteChunk.
    Parameters:
      `src` - the source chunk
    Throws:
      `IOException` - if writing fails

  - ### append

    public void append(byte[] src, int off, int len) throws IOException
    Add data to the buffer.
    Parameters:
      `src` - Bytes array
      `off` - Offset
      `len` - Length
    Throws:
      `IOException` - Writing overflow data to the output channel failed

  - ### append

    public void append(ByteBuffer from) throws IOException
    Add data to the buffer.
    Parameters:
      `from` - the ByteBuffer with the data
    Throws:
      `IOException` - Writing overflow data to the output channel failed

  - ### subtract

    public int subtract() throws IOException
    Reads and removes the next byte from this chunk.
    Returns:
      the byte value (0-255) or -1 if end of data
    Throws:
      `IOException` - if reading from input channel fails

  - ### subtractB

    @Deprecated public byte subtractB() throws IOException
    Deprecated.
    Use `subtract()` instead. This method cannot distinguish between EOF (-1) and the legitimate byte value 0xFF because it returns `byte`.
    Reads and removes the next byte from this chunk.
    Returns:
      the byte value or -1 if end of data
    Throws:
      `IOException` - if reading from input channel fails

  - ### subtract

    public int subtract(byte[] dest, int off, int len) throws IOException
    Reads bytes into the specified array.
    Parameters:
      `dest` - destination array
      `off` - offset
      `len` - maximum length
    Returns:
      number of bytes read or -1 if end of data
    Throws:
      `IOException` - if reading from input channel fails

  - ### subtract

    public int subtract(ByteBuffer to) throws IOException
    Transfers bytes from the buffer to the specified ByteBuffer. After the operation the position of the ByteBuffer will be returned to the one before the operation, the limit will be the position incremented by the number of the transferred bytes.
    Parameters:
      `to` - the ByteBuffer into which bytes are to be written.
    Returns:
      an integer specifying the actual number of bytes read, or -1 if the end of the stream is reached
    Throws:
      `IOException` - if an input or output exception has occurred

  - ### flushBuffer

    public void flushBuffer() throws IOException
    Send the buffer to the sink. Called by append() when the limit is reached. You can also call it explicitly to force the data to be written.
    Throws:
      `IOException` - Writing overflow data to the output channel failed

  - ### makeSpace

    public void makeSpace(int count)
    Make space for len bytes. If len is small, allocate a reserve space too. Never grow bigger than the limit or `AbstractChunk.ARRAY_MAX_SIZE`.
    Parameters:
      `count` - The size

  - ### toString

    public String toString()
    Overrides:
      `toString` in class `Object`

  - ### toString

    public String toString(CodingErrorAction malformedInputAction, CodingErrorAction unmappableCharacterAction) throws CharacterCodingException
    Converts the byte chunk to a String using the configured charset.
    Parameters:
      `malformedInputAction` - action for malformed input
      `unmappableCharacterAction` - action for unmappable characters
    Returns:
      the string representation
    Throws:
      `CharacterCodingException` - if conversion fails

  - ### toStringInternal

    public String toStringInternal(CodingErrorAction malformedInputAction, CodingErrorAction unmappableCharacterAction) throws CharacterCodingException
    Converts the current content of the byte buffer to a String using the configured character set.
    Parameters:
      `malformedInputAction` - Action to take if the input is malformed
      `unmappableCharacterAction` - Action to take if a byte sequence can't be mapped to a character
    Returns:
      The result of converting the bytes to a String
    Throws:
      `CharacterCodingException` - If an error occurs during the conversion

  - ### getLong

    public long getLong()
    Parses the byte chunk content as a long integer.
    Returns:
      the parsed long value

  - ### equals

    public boolean equals(Object obj)
    Description copied from class: `AbstractChunk`

    Sub-classes must provide an equals implementation that is consistent with `AbstractChunk.hashCode()`.

    Specified by:
      `equals` in class `AbstractChunk`

  - ### equals

    public boolean equals(String s)
    Compares the message bytes to the specified String object.

    NOTE: This only works for characters in the range 0-127.

    Parameters:
      `s` - the String to compare
    Returns:
      `true` if the comparison succeeded, `false` otherwise

  - ### equalsIgnoreCase

    public boolean equalsIgnoreCase(String s)
    Compares the message bytes to the specified String object.

    NOTE: This only works for characters in the range 0-255.

    Parameters:
      `s` - the String to compare
    Returns:
      `true` if the comparison succeeded, `false` otherwise

  - ### equals

    public boolean equals(ByteChunk bb)
    Compares this chunk to another ByteChunk.
    Parameters:
      `bb` - the ByteChunk to compare
    Returns:
      true if equal

  - ### equals

    public boolean equals(byte[] b2, int off2, int len2)
    Compares this chunk to a byte array region.
    Parameters:
      `b2` - the byte array
      `off2` - offset
      `len2` - length
    Returns:
      true if equal

  - ### equalsIgnoreCase

    public boolean equalsIgnoreCase(byte[] b2, int off2, int len2)
    Compares this chunk to a byte array region, ignoring case.
    Parameters:
      `b2` - the byte array
      `off2` - offset
      `len2` - length
    Returns:
      true if equal

  - ### equals

    public boolean equals(CharChunk cc)
    Compares this chunk to a CharChunk.
    Parameters:
      `cc` - the CharChunk to compare
    Returns:
      true if equal

  - ### equals

    public boolean equals(char[] c2, int off2, int len2)
    Compares the message bytes to the specified char array.

    NOTE: This only works for characters in the range 0-127.

    Parameters:
      `c2` - the array to compare to
      `off2` - offset
      `len2` - length
    Returns:
      `true` if the comparison succeeded, `false` otherwise

  - ### startsWith

    public boolean startsWith(String s, int pos)
    Returns true if the buffer starts with the specified string when tested in a case-sensitive manner.

    NOTE: This only works for characters in the range 0-127.

    Parameters:
      `s` - the string
      `pos` - The position
    Returns:
      `true` if the start matches

  - ### startsWithIgnoreCase

    public boolean startsWithIgnoreCase(String s, int pos)
    Returns true if the buffer starts with the specified string when tested in a case-insensitive manner.

    NOTE: This only works for characters in the range 0-255.

    Parameters:
      `s` - the string
      `pos` - The position
    Returns:
      `true` if the start matches

  - ### getBufferElement

    protected int getBufferElement(int index)
    Description copied from class: `AbstractChunk`
    Returns the element at the specified index in the buffer.
    Specified by:
      `getBufferElement` in class `AbstractChunk`
    Parameters:
      `index` - the element location in the buffer
    Returns:
      the element

  - ### indexOf

    public int indexOf(char c, int starting)
    Returns the first instance of the given character in this ByteChunk starting at the specified byte. If the character is not found, -1 is returned.

    NOTE: This only works for characters in the range 0-127.

    Parameters:
      `c` - The character
      `starting` - The start position
    Returns:
      The position of the first instance of the character or -1 if the character is not found.

  - ### indexOf

    public static int indexOf(byte[] bytes, int start, int end, char s)
    Returns the first instance of the given character in the given byte array between the specified start and end.

    NOTE: This only works for characters in the range 0-127.

    Parameters:
      `bytes` - The array to search
      `start` - The point to start searching from in the array
      `end` - The point to stop searching in the array
      `s` - The character to search for
    Returns:
      The position of the first instance of the character or -1 if the character is not found.

  - ### findByte

    public static int findByte(byte[] bytes, int start, int end, byte b)
    Returns the first instance of the given byte in the byte array between the specified start and end.
    Parameters:
      `bytes` - The byte array to search
      `start` - The point to start searching from in the byte array
      `end` - The point to stop searching in the byte array
      `b` - The byte to search for
    Returns:
      The position of the first instance of the byte or -1 if the byte is not found.

  - ### findBytes

    public static int findBytes(byte[] bytes, int start, int end, byte[] b)
    Returns the first instance of the given bytes in the byte array between the specified start and end.
    Parameters:
      `bytes` - The byte array to search
      `start` - The point to start searching from in the byte array
      `end` - The point to stop searching in the byte array
      `b` - The array of bytes to search for
    Returns:
      The position of the first instance of the byte or -1 if the byte is not found.

  - ### convertToBytes

    public static byte[] convertToBytes(String value)
    Convert specified String to a byte array. This ONLY WORKS for ascii, UTF chars will be truncated.
    Parameters:
      `value` - to convert to byte array
    Returns:
      the byte array value