ByteBufUtil (Netty API Reference (4.1.115.Final))

java.lang.Object
- io.netty.buffer.ByteBufUtil

```
public final class ByteBufUtil
extends Object
```
A collection of utility methods that is related with handling ByteBuf, such as the generation of hex dump and swapping an integer's byte order.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static void`	`appendPrettyHexDump(StringBuilder dump, ByteBuf buf)` Appends the prettified multi-line hexadecimal dump of the specified `ByteBuf` to the specified `StringBuilder` that is easy to read by humans.
`static void`	`appendPrettyHexDump(StringBuilder dump, ByteBuf buf, int offset, int length)` Appends the prettified multi-line hexadecimal dump of the specified `ByteBuf` to the specified `StringBuilder` that is easy to read by humans, starting at the given `offset` using the given `length`.
`static int`	`compare(ByteBuf bufferA, ByteBuf bufferB)` Compares the two specified buffers as described in `ByteBuf.compareTo(ByteBuf)`.
`static void`	`copy(AsciiString src, ByteBuf dst)` Copies the all content of `src` to a `ByteBuf` using `ByteBuf.writeBytes(byte[], int, int)`.
`static void`	`copy(AsciiString src, int srcIdx, ByteBuf dst, int length)` Copies the content of `src` to a `ByteBuf` using `ByteBuf.writeBytes(byte[], int, int)`.
`static void`	`copy(AsciiString src, int srcIdx, ByteBuf dst, int dstIdx, int length)` Copies the content of `src` to a `ByteBuf` using `ByteBuf.setBytes(int, byte[], int, int)`.
`static byte`	`decodeHexByte(CharSequence s, int pos)` Decode a 2-digit hex byte from within a string.
`static byte[]`	`decodeHexDump(CharSequence hexDump)` Decodes a string generated by `hexDump(byte[])`
`static byte[]`	`decodeHexDump(CharSequence hexDump, int fromIndex, int length)` Decodes part of a string generated by `hexDump(byte[])`
`static ByteBuf`	`encodeString(ByteBufAllocator alloc, CharBuffer src, Charset charset)` Encode the given `CharBuffer` using the given `Charset` into a new `ByteBuf` which is allocated via the `ByteBufAllocator`.
`static ByteBuf`	`encodeString(ByteBufAllocator alloc, CharBuffer src, Charset charset, int extraCapacity)` Encode the given `CharBuffer` using the given `Charset` into a new `ByteBuf` which is allocated via the `ByteBufAllocator`.
`static ByteBuf`	`ensureAccessible(ByteBuf buffer)`
`static boolean`	`ensureWritableSuccess(int ensureWritableResult)` Used to determine if the return value of `ByteBuf.ensureWritable(int, boolean)` means that there is adequate space and a write operation will succeed.
`static boolean`	`equals(ByteBuf bufferA, ByteBuf bufferB)` Returns `true` if and only if the two specified buffers are identical to each other as described in `ByteBuf.equals(Object)`.
`static boolean`	`equals(ByteBuf a, int aStartIndex, ByteBuf b, int bStartIndex, int length)` Returns `true` if and only if the two specified buffers are identical to each other for `length` bytes starting at `aStartIndex` index for the `a` buffer and `bStartIndex` index for the `b` buffer.
`static byte[]`	`getBytes(ByteBuf buf)` Create a copy of the underlying storage from `buf` into a byte array.
`static byte[]`	`getBytes(ByteBuf buf, int start, int length)` Create a copy of the underlying storage from `buf` into a byte array.
`static byte[]`	`getBytes(ByteBuf buf, int start, int length, boolean copy)` Return an array of the underlying storage from `buf` into a byte array.
`static int`	`hashCode(ByteBuf buffer)` Calculates the hash code of the specified buffer.
`static String`	`hexDump(byte[] array)` Returns a hex dump of the specified byte array.
`static String`	`hexDump(byte[] array, int fromIndex, int length)` Returns a hex dump of the specified byte array's sub-region.
`static String`	`hexDump(ByteBuf buffer)` Returns a hex dump of the specified buffer's readable bytes.
`static String`	`hexDump(ByteBuf buffer, int fromIndex, int length)` Returns a hex dump of the specified buffer's sub-region.
`static int`	`indexOf(ByteBuf needle, ByteBuf haystack)` Returns the reader index of needle in haystack, or -1 if needle is not in haystack.
`static int`	`indexOf(ByteBuf buffer, int fromIndex, int toIndex, byte value)` The default implementation of `ByteBuf.indexOf(int, int, byte)`.
`static boolean`	`isAccessible(ByteBuf buffer)`
`static boolean`	`isText(ByteBuf buf, Charset charset)` Returns `true` if the given `ByteBuf` is valid text using the given `Charset`, otherwise return `false`.
`static boolean`	`isText(ByteBuf buf, int index, int length, Charset charset)` Returns `true` if the specified `ByteBuf` starting at `index` with `length` is valid text using the given `Charset`, otherwise return `false`.
`static String`	`prettyHexDump(ByteBuf buffer)` Returns a multi-line hexadecimal dump of the specified `ByteBuf` that is easy to read by humans.
`static String`	`prettyHexDump(ByteBuf buffer, int offset, int length)` Returns a multi-line hexadecimal dump of the specified `ByteBuf` that is easy to read by humans, starting at the given `offset` using the given `length`.
`static ByteBuf`	`readBytes(ByteBufAllocator alloc, ByteBuf buffer, int length)` Read the given amount of bytes into a new `ByteBuf` that is allocated from the `ByteBufAllocator`.
`static int`	`readIntBE(ByteBuf buf)` Reads a big-endian 32-bit integer from the buffer.
`static int`	`readUnsignedShortBE(ByteBuf buf)` Reads a big-endian unsigned 16-bit short integer from the buffer.
`static int`	`reserveAndWriteUtf8(ByteBuf buf, CharSequence seq, int reserveBytes)` Encode a `CharSequence` in UTF-8 and write it into `reserveBytes` of a `ByteBuf`.
`static int`	`reserveAndWriteUtf8(ByteBuf buf, CharSequence seq, int start, int end, int reserveBytes)` Equivalent to `reserveAndWriteUtf8(buf, seq.subSequence(start, end), reserveBytes)` but avoids subsequence object allocation if possible.
`static void`	`setLeakListener(ResourceLeakDetector.LeakListener leakListener)` Set `AbstractByteBuf.leakDetector`'s `ResourceLeakDetector.LeakListener`.
`static ByteBuf`	`setShortBE(ByteBuf buf, int index, int shortValue)` Sets a big-endian 16-bit short integer to the buffer.
`static int`	`swapInt(int value)` Toggles the endianness of the specified 32-bit integer.
`static long`	`swapLong(long value)` Toggles the endianness of the specified 64-bit long integer.
`static int`	`swapMedium(int value)` Toggles the endianness of the specified 24-bit medium integer.
`static short`	`swapShort(short value)` Toggles the endianness of the specified 16-bit short integer.
`static ByteBuf`	`threadLocalDirectBuffer()` Returns a cached thread-local direct buffer, if available.
`static int`	`utf8Bytes(CharSequence seq)` Returns the exact bytes length of UTF8 character sequence.
`static int`	`utf8Bytes(CharSequence seq, int start, int end)` Equivalent to `utf8Bytes(seq.subSequence(start, end))` but avoids subsequence object allocation.
`static int`	`utf8MaxBytes(CharSequence seq)` Returns max bytes length of UTF8 character sequence.
`static int`	`utf8MaxBytes(int seqLength)` Returns max bytes length of UTF8 character sequence of the given length.
`static ByteBuf`	`writeAscii(ByteBufAllocator alloc, CharSequence seq)` Encode a `CharSequence` in ASCII and write it to a `ByteBuf` allocated with `alloc`.
`static int`	`writeAscii(ByteBuf buf, CharSequence seq)` Encode a `CharSequence` in ASCII and write it to a `ByteBuf`.
`static ByteBuf`	`writeMediumBE(ByteBuf buf, int mediumValue)` Writes a big-endian 24-bit medium integer to the buffer.
`static ByteBuf`	`writeShortBE(ByteBuf buf, int shortValue)` Writes a big-endian 16-bit short integer to the buffer.
`static ByteBuf`	`writeUtf8(ByteBufAllocator alloc, CharSequence seq)` Encode a `CharSequence` in UTF-8 and write it to a `ByteBuf` allocated with `alloc`.
`static int`	`writeUtf8(ByteBuf buf, CharSequence seq)` Encode a `CharSequence` in UTF-8 and write it to a `ByteBuf`.
`static int`	`writeUtf8(ByteBuf buf, CharSequence seq, int start, int end)` Equivalent to `writeUtf8(buf, seq.subSequence(start, end))` but avoids subsequence object allocation.

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

- Method Detail
  - isAccessible
```
public static boolean isAccessible(ByteBuf buffer)
```
    Returns:
    
    whether the specified buffer has a nonzero ref count
  - ensureAccessible
```
public static ByteBuf ensureAccessible(ByteBuf buffer)
```
    Returns:
    
    the passed in buffer
    
    Throws:
    
    IllegalReferenceCountException - if the buffer has a zero ref count
  - hexDump
```
public static String hexDump(ByteBuf buffer)
```
    Returns a hex dump of the specified buffer's readable bytes.
  - hexDump
```
public static String hexDump(ByteBuf buffer,
                             int fromIndex,
                             int length)
```
    Returns a hex dump of the specified buffer's sub-region.
  - hexDump
```
public static String hexDump(byte[] array)
```
    Returns a hex dump of the specified byte array.
  - hexDump
```
public static String hexDump(byte[] array,
                             int fromIndex,
                             int length)
```
    Returns a hex dump of the specified byte array's sub-region.
  - decodeHexByte
```
public static byte decodeHexByte(CharSequence s,
                                 int pos)
```
    Decode a 2-digit hex byte from within a string.
  - decodeHexDump
```
public static byte[] decodeHexDump(CharSequence hexDump)
```
    Decodes a string generated by hexDump(byte[])
  - decodeHexDump
```
public static byte[] decodeHexDump(CharSequence hexDump,
                                   int fromIndex,
                                   int length)
```
    Decodes part of a string generated by hexDump(byte[])
  - ensureWritableSuccess
```
public static boolean ensureWritableSuccess(int ensureWritableResult)
```
    Used to determine if the return value of ByteBuf.ensureWritable(int, boolean) means that there is adequate space and a write operation will succeed.
    
    Parameters:
    
    ensureWritableResult - The return value from ByteBuf.ensureWritable(int, boolean).
    
    Returns:
    
    true if ensureWritableResult means that there is adequate space and a write operation will succeed.
  - hashCode
```
public static int hashCode(ByteBuf buffer)
```
    Calculates the hash code of the specified buffer. This method is useful when implementing a new buffer type.
  - indexOf
```
public static int indexOf(ByteBuf needle,
                          ByteBuf haystack)
```
    Returns the reader index of needle in haystack, or -1 if needle is not in haystack. This method uses the Two-Way string matching algorithm, which yields O(1) space complexity and excellent performance.
  - equals
```
public static boolean equals(ByteBuf a,
                             int aStartIndex,
                             ByteBuf b,
                             int bStartIndex,
                             int length)
```
    Returns true if and only if the two specified buffers are identical to each other for length bytes starting at aStartIndex index for the a buffer and bStartIndex index for the b buffer. A more compact way to express this is:
    a[aStartIndex : aStartIndex + length] == b[bStartIndex : bStartIndex + length]
  - equals
```
public static boolean equals(ByteBuf bufferA,
                             ByteBuf bufferB)
```
    Returns true if and only if the two specified buffers are identical to each other as described in ByteBuf.equals(Object). This method is useful when implementing a new buffer type.
  - compare
```
public static int compare(ByteBuf bufferA,
                          ByteBuf bufferB)
```
    Compares the two specified buffers as described in ByteBuf.compareTo(ByteBuf). This method is useful when implementing a new buffer type.
  - indexOf
```
public static int indexOf(ByteBuf buffer,
                          int fromIndex,
                          int toIndex,
                          byte value)
```
    The default implementation of ByteBuf.indexOf(int, int, byte). This method is useful when implementing a new buffer type.
  - swapShort
```
public static short swapShort(short value)
```
    Toggles the endianness of the specified 16-bit short integer.
  - swapMedium
```
public static int swapMedium(int value)
```
    Toggles the endianness of the specified 24-bit medium integer.
  - swapInt
```
public static int swapInt(int value)
```
    Toggles the endianness of the specified 32-bit integer.
  - swapLong
```
public static long swapLong(long value)
```
    Toggles the endianness of the specified 64-bit long integer.
  - writeShortBE
```
public static ByteBuf writeShortBE(ByteBuf buf,
                                   int shortValue)
```
    Writes a big-endian 16-bit short integer to the buffer.
  - setShortBE
```
public static ByteBuf setShortBE(ByteBuf buf,
                                 int index,
                                 int shortValue)
```
    Sets a big-endian 16-bit short integer to the buffer.
  - writeMediumBE
```
public static ByteBuf writeMediumBE(ByteBuf buf,
                                    int mediumValue)
```
    Writes a big-endian 24-bit medium integer to the buffer.
  - readUnsignedShortBE
```
public static int readUnsignedShortBE(ByteBuf buf)
```
    Reads a big-endian unsigned 16-bit short integer from the buffer.
  - readIntBE
```
public static int readIntBE(ByteBuf buf)
```
    Reads a big-endian 32-bit integer from the buffer.
  - readBytes
```
public static ByteBuf readBytes(ByteBufAllocator alloc,
                                ByteBuf buffer,
                                int length)
```
    Read the given amount of bytes into a new ByteBuf that is allocated from the ByteBufAllocator.
  - writeUtf8
```
public static ByteBuf writeUtf8(ByteBufAllocator alloc,
                                CharSequence seq)
```
    Encode a CharSequence in UTF-8 and write it to a ByteBuf allocated with alloc.
    
    Parameters:
    
    alloc - The allocator used to allocate a new ByteBuf.
    
    seq - The characters to write into a buffer.
    
    Returns:
    
    The ByteBuf which contains the UTF-8 encoded result.
  - writeUtf8
```
public static int writeUtf8(ByteBuf buf,
                            CharSequence seq)
```
    Encode a CharSequence in UTF-8 and write it to a ByteBuf.
    It behaves like reserveAndWriteUtf8(ByteBuf, CharSequence, int) with reserveBytes computed by utf8MaxBytes(CharSequence).
    This method returns the actual number of bytes written.
  - writeUtf8
```
public static int writeUtf8(ByteBuf buf,
                            CharSequence seq,
                            int start,
                            int end)
```
    Equivalent to writeUtf8(buf, seq.subSequence(start, end)) but avoids subsequence object allocation.
  - reserveAndWriteUtf8
```
public static int reserveAndWriteUtf8(ByteBuf buf,
                                      CharSequence seq,
                                      int reserveBytes)
```
    Encode a CharSequence in UTF-8 and write it into reserveBytes of a ByteBuf.
    The reserveBytes must be computed (ie eagerly using utf8MaxBytes(CharSequence) or exactly with utf8Bytes(CharSequence)) to ensure this method to not fail: for performance reasons the index checks will be performed using just reserveBytes.
    This method returns the actual number of bytes written.
  - reserveAndWriteUtf8
```
public static int reserveAndWriteUtf8(ByteBuf buf,
                                      CharSequence seq,
                                      int start,
                                      int end,
                                      int reserveBytes)
```
    Equivalent to reserveAndWriteUtf8(buf, seq.subSequence(start, end), reserveBytes) but avoids subsequence object allocation if possible.
    
    Returns:
    
    actual number of bytes written
  - utf8MaxBytes
```
public static int utf8MaxBytes(int seqLength)
```
    Returns max bytes length of UTF8 character sequence of the given length.
  - utf8MaxBytes
```
public static int utf8MaxBytes(CharSequence seq)
```
    Returns max bytes length of UTF8 character sequence.
    It behaves like utf8MaxBytes(int) applied to seq CharSequence.length().
  - utf8Bytes
```
public static int utf8Bytes(CharSequence seq)
```
    Returns the exact bytes length of UTF8 character sequence.
    This method is producing the exact length according to writeUtf8(ByteBuf, CharSequence).
  - utf8Bytes
```
public static int utf8Bytes(CharSequence seq,
                            int start,
                            int end)
```
    Equivalent to utf8Bytes(seq.subSequence(start, end)) but avoids subsequence object allocation.
    This method is producing the exact length according to writeUtf8(ByteBuf, CharSequence, int, int).
  - writeAscii
```
public static ByteBuf writeAscii(ByteBufAllocator alloc,
                                 CharSequence seq)
```
    Encode a CharSequence in ASCII and write it to a ByteBuf allocated with alloc.
    
    Parameters:
    
    alloc - The allocator used to allocate a new ByteBuf.
    
    seq - The characters to write into a buffer.
    
    Returns:
    
    The ByteBuf which contains the ASCII encoded result.
  - writeAscii
```
public static int writeAscii(ByteBuf buf,
                             CharSequence seq)
```
    Encode a CharSequence in ASCII and write it to a ByteBuf. This method returns the actual number of bytes written.
  - encodeString
```
public static ByteBuf encodeString(ByteBufAllocator alloc,
                                   CharBuffer src,
                                   Charset charset)
```
    Encode the given CharBuffer using the given Charset into a new ByteBuf which is allocated via the ByteBufAllocator.
  - encodeString
```
public static ByteBuf encodeString(ByteBufAllocator alloc,
                                   CharBuffer src,
                                   Charset charset,
                                   int extraCapacity)
```
    Encode the given CharBuffer using the given Charset into a new ByteBuf which is allocated via the ByteBufAllocator.
    
    Parameters:
    
    alloc - The ByteBufAllocator to allocate ByteBuf.
    
    src - The CharBuffer to encode.
    
    charset - The specified Charset.
    
    extraCapacity - the extra capacity to alloc except the space for decoding.
  - threadLocalDirectBuffer
```
public static ByteBuf threadLocalDirectBuffer()
```
    Returns a cached thread-local direct buffer, if available.
    
    Returns:
    
    a cached thread-local direct buffer, if available. null otherwise.
  - getBytes
```
public static byte[] getBytes(ByteBuf buf)
```
    Create a copy of the underlying storage from buf into a byte array. The copy will start at ByteBuf.readerIndex() and copy ByteBuf.readableBytes() bytes.
  - getBytes
```
public static byte[] getBytes(ByteBuf buf,
                              int start,
                              int length)
```
    Create a copy of the underlying storage from buf into a byte array. The copy will start at start and copy length bytes.
  - getBytes
```
public static byte[] getBytes(ByteBuf buf,
                              int start,
                              int length,
                              boolean copy)
```
    Return an array of the underlying storage from buf into a byte array. The copy will start at start and copy length bytes. If copy is true a copy will be made of the memory. If copy is false the underlying storage will be shared, if possible.
  - copy
```
public static void copy(AsciiString src,
                        ByteBuf dst)
```
    Copies the all content of src to a ByteBuf using ByteBuf.writeBytes(byte[], int, int).
    
    Parameters:
    
    src - the source string to copy
    
    dst - the destination buffer
  - copy
```
public static void copy(AsciiString src,
                        int srcIdx,
                        ByteBuf dst,
                        int dstIdx,
                        int length)
```
    Copies the content of src to a ByteBuf using ByteBuf.setBytes(int, byte[], int, int). Unlike the copy(AsciiString, ByteBuf) and copy(AsciiString, int, ByteBuf, int) methods, this method do not increase a writerIndex of dst buffer.
    
    Parameters:
    
    src - the source string to copy
    
    srcIdx - the starting offset of characters to copy
    
    dst - the destination buffer
    
    dstIdx - the starting offset in the destination buffer
    
    length - the number of characters to copy
  - copy
```
public static void copy(AsciiString src,
                        int srcIdx,
                        ByteBuf dst,
                        int length)
```
    Copies the content of src to a ByteBuf using ByteBuf.writeBytes(byte[], int, int).
    
    Parameters:
    
    src - the source string to copy
    
    srcIdx - the starting offset of characters to copy
    
    dst - the destination buffer
    
    length - the number of characters to copy
  - prettyHexDump
```
public static String prettyHexDump(ByteBuf buffer)
```
    Returns a multi-line hexadecimal dump of the specified ByteBuf that is easy to read by humans.
  - prettyHexDump
```
public static String prettyHexDump(ByteBuf buffer,
                                   int offset,
                                   int length)
```
    Returns a multi-line hexadecimal dump of the specified ByteBuf that is easy to read by humans, starting at the given offset using the given length.
  - appendPrettyHexDump
```
public static void appendPrettyHexDump(StringBuilder dump,
                                       ByteBuf buf)
```
    Appends the prettified multi-line hexadecimal dump of the specified ByteBuf to the specified StringBuilder that is easy to read by humans.
  - appendPrettyHexDump
```
public static void appendPrettyHexDump(StringBuilder dump,
                                       ByteBuf buf,
                                       int offset,
                                       int length)
```
    Appends the prettified multi-line hexadecimal dump of the specified ByteBuf to the specified StringBuilder that is easy to read by humans, starting at the given offset using the given length.
  - isText
```
public static boolean isText(ByteBuf buf,
                             Charset charset)
```
    Returns true if the given ByteBuf is valid text using the given Charset, otherwise return false.
    
    Parameters:
    
    buf - The given ByteBuf.
    
    charset - The specified Charset.
  - isText
```
public static boolean isText(ByteBuf buf,
                             int index,
                             int length,
                             Charset charset)
```
    Returns true if the specified ByteBuf starting at index with length is valid text using the given Charset, otherwise return false.
    
    Parameters:
    
    buf - The given ByteBuf.
    
    index - The start index of the specified buffer.
    
    length - The length of the specified buffer.
    
    charset - The specified Charset.
    
    Throws:
    
    IndexOutOfBoundsException - if index + length is greater than buf.readableBytes
  - setLeakListener
```
public static void setLeakListener(ResourceLeakDetector.LeakListener leakListener)
```
    Set AbstractByteBuf.leakDetector's ResourceLeakDetector.LeakListener.
    
    Parameters:
    
    leakListener - If leakListener is not null, it will be notified once a ByteBuf leak is detected.

Class ByteBufUtil

Method Summary

Methods inherited from class java.lang.Object

Method Detail

isAccessible

ensureAccessible

hexDump

hexDump

hexDump

hexDump

decodeHexByte

decodeHexDump

decodeHexDump

ensureWritableSuccess

hashCode

indexOf

equals

equals

compare

indexOf

swapShort

swapMedium

swapInt

swapLong

writeShortBE

setShortBE

writeMediumBE

readUnsignedShortBE

readIntBE

readBytes

writeUtf8

writeUtf8

writeUtf8

reserveAndWriteUtf8

reserveAndWriteUtf8

utf8MaxBytes

utf8MaxBytes

utf8Bytes

utf8Bytes

writeAscii

writeAscii

encodeString

encodeString

threadLocalDirectBuffer

getBytes

getBytes

getBytes

copy

copy

copy

prettyHexDump

prettyHexDump

appendPrettyHexDump

appendPrettyHexDump

isText

isText

setLeakListener