Package com.google.common.io

Class ByteStreams

java.lang.Object

com.google.common.io.ByteStreams

@GwtIncompatible
public final class ByteStreams
extends Object

Provides utility methods for working with byte arrays and I/O streams.

Since:

1.0

Author:

Chris Nokleberg, Colin Decker

Method Summary

Modifier and Type	Method	Description
static long	copy(InputStream from, OutputStream to)	Copies all bytes from the input stream to the output stream.
static long	copy(ReadableByteChannel from, WritableByteChannel to)	Copies all bytes from the readable channel to the writable channel.
static long	exhaust(InputStream in)	Reads and discards data from the given InputStream until the end of the stream is reached.
static InputStream	limit(InputStream in, long limit)	Wraps a InputStream, limiting the number of bytes which can be read.
static ByteArrayDataInput	newDataInput(byte[] bytes)	Returns a new ByteArrayDataInput instance to read from the bytes array from the beginning.
static ByteArrayDataInput	newDataInput(byte[] bytes, int start)	Returns a new ByteArrayDataInput instance to read from the bytes array, starting at the given position.
static ByteArrayDataInput	newDataInput(ByteArrayInputStream byteArrayInputStream)	Returns a new ByteArrayDataInput instance to read from the given ByteArrayInputStream.
static ByteArrayDataOutput	newDataOutput()	Returns a new ByteArrayDataOutput instance with a default size.
static ByteArrayDataOutput	newDataOutput(int size)	Returns a new ByteArrayDataOutput instance sized to hold size bytes before resizing.
static ByteArrayDataOutput	newDataOutput(ByteArrayOutputStream byteArrayOutputStream)	Returns a new ByteArrayDataOutput instance which writes to the given ByteArrayOutputStream.
static OutputStream	nullOutputStream()	Returns an OutputStream that simply discards written bytes.
static int	read(InputStream in, byte[] b, int off, int len)	Reads some bytes from an input stream and stores them into the buffer array b.
static <T extends @Nullable Object> T	readBytes(InputStream input, ByteProcessor<T> processor)	Process the bytes of the given input stream using the given processor.
static void	readFully(InputStream in, byte[] b)	Attempts to read enough bytes from the stream to fill the given byte array, with the same behavior as DataInput.readFully(byte[]).
static void	readFully(InputStream in, byte[] b, int off, int len)	Attempts to read len bytes from the stream into the given array starting at off, with the same behavior as DataInput.readFully(byte[], int, int).
static void	skipFully(InputStream in, long n)	Discards n bytes of data from the input stream.
static byte[]	toByteArray(InputStream in)	Reads all bytes from an input stream into a byte array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

copy

@CanIgnoreReturnValue
public static long copy(InputStream from,
                        OutputStream to)
                 throws IOException

Copies all bytes from the input stream to the output stream. Does not close or flush either stream.

Parameters:

from - the input stream to read from

to - the output stream to write to

Returns:

the number of bytes copied

Throws:

IOException - if an I/O error occurs

copy

@CanIgnoreReturnValue
public static long copy(ReadableByteChannel from,
                        WritableByteChannel to)
                 throws IOException

Copies all bytes from the readable channel to the writable channel. Does not close or flush either channel.

Parameters:

from - the readable channel to read from

to - the writable channel to write to

Returns:

the number of bytes copied

Throws:

IOException - if an I/O error occurs

toByteArray

public static byte[] toByteArray(InputStream in)
                          throws IOException

Reads all bytes from an input stream into a byte array. Does not close the stream.

Parameters:

in - the input stream to read from

Returns:

a byte array containing all the bytes from the stream

Throws:

IOException - if an I/O error occurs

exhaust

@CanIgnoreReturnValue
@Beta
public static long exhaust(InputStream in)
                    throws IOException

Reads and discards data from the given InputStream until the end of the stream is reached. Returns the total number of bytes read. Does not close the stream.

Throws:

IOException

Since:

20.0

newDataInput

@Beta
public static ByteArrayDataInput newDataInput(byte[] bytes)

Returns a new ByteArrayDataInput instance to read from the bytes array from the beginning.

newDataInput

@Beta
public static ByteArrayDataInput newDataInput(byte[] bytes,
                                              int start)

Returns a new ByteArrayDataInput instance to read from the bytes array, starting at the given position.

Throws:

IndexOutOfBoundsException - if start is negative or greater than the length of the array

newDataInput

@Beta
public static ByteArrayDataInput newDataInput(ByteArrayInputStream byteArrayInputStream)

Returns a new ByteArrayDataInput instance to read from the given ByteArrayInputStream. The given input stream is not reset before being read from by the returned ByteArrayDataInput.

Since:

17.0

newDataOutput

@Beta
public static ByteArrayDataOutput newDataOutput()

Returns a new ByteArrayDataOutput instance with a default size.

newDataOutput

@Beta
public static ByteArrayDataOutput newDataOutput(int size)

Returns a new ByteArrayDataOutput instance sized to hold size bytes before resizing.

Throws:

IllegalArgumentException - if size is negative

newDataOutput

@Beta
public static ByteArrayDataOutput newDataOutput(ByteArrayOutputStream byteArrayOutputStream)

Returns a new ByteArrayDataOutput instance which writes to the given ByteArrayOutputStream. The given output stream is not reset before being written to by the returned ByteArrayDataOutput and new data will be appended to any existing content.

Note that if the given output stream was not empty or is modified after the ByteArrayDataOutput is created, the contract for ByteArrayDataOutput.toByteArray() will not be honored (the bytes returned in the byte array may not be exactly what was written via calls to ByteArrayDataOutput).

Since:

17.0

nullOutputStream

@Beta
public static OutputStream nullOutputStream()

Returns an OutputStream that simply discards written bytes.

Since:

14.0 (since 1.0 as com.google.common.io.NullOutputStream)

limit

@Beta
public static InputStream limit(InputStream in,
                                long limit)

Wraps a InputStream, limiting the number of bytes which can be read.

Parameters:

in - the input stream to be wrapped

limit - the maximum number of bytes to be read

Returns:

a length-limited InputStream

Since:

14.0 (since 1.0 as com.google.common.io.LimitInputStream)

readFully

@Beta
public static void readFully(InputStream in,
                             byte[] b)
                      throws IOException

Attempts to read enough bytes from the stream to fill the given byte array, with the same behavior as DataInput.readFully(byte[]). Does not close the stream.

Parameters:

in - the input stream to read from.

b - the buffer into which the data is read.

Throws:

EOFException - if this stream reaches the end before reading all the bytes.

IOException - if an I/O error occurs.

readFully

@Beta
public static void readFully(InputStream in,
                             byte[] b,
                             int off,
                             int len)
                      throws IOException

Attempts to read len bytes from the stream into the given array starting at off, with the same behavior as DataInput.readFully(byte[], int, int). Does not close the stream.

Parameters:

in - the input stream to read from.

b - the buffer into which the data is read.

off - an int specifying the offset into the data.

len - an int specifying the number of bytes to read.

Throws:

EOFException - if this stream reaches the end before reading all the bytes.

IOException - if an I/O error occurs.

skipFully

@Beta
public static void skipFully(InputStream in,
                             long n)
                      throws IOException

Discards n bytes of data from the input stream. This method will block until the full amount has been skipped. Does not close the stream.

Parameters:

in - the input stream to read from

n - the number of bytes to skip

Throws:

EOFException - if this stream reaches the end before skipping all the bytes

IOException - if an I/O error occurs, or the stream does not support skipping

readBytes

@Beta
@CanIgnoreReturnValue
public static <T extends @Nullable Object> T readBytes(InputStream input,
                                                       ByteProcessor<T> processor)
                                                throws IOException

Process the bytes of the given input stream using the given processor.

Parameters:

input - the input stream to process

processor - the object to which to pass the bytes of the stream

Returns:

the result of the byte processor

Throws:

IOException - if an I/O error occurs

Since:

14.0

read

@Beta
@CanIgnoreReturnValue
public static int read(InputStream in,
                       byte[] b,
                       int off,
                       int len)
                throws IOException

Reads some bytes from an input stream and stores them into the buffer array b. This method blocks until len bytes of input data have been read into the array, or end of file is detected. The number of bytes read is returned, possibly zero. Does not close the stream.

A caller can detect EOF if the number of bytes read is less than len. All subsequent calls on the same stream will return zero.

If b is null, a NullPointerException is thrown. If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown. If len is zero, then no bytes are read. Otherwise, the first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len.

Parameters:

in - the input stream to read from

b - the buffer into which the data is read

off - an int specifying the offset into the data

len - an int specifying the number of bytes to read

Returns:

the number of bytes read

Throws:

IOException - if an I/O error occurs

IndexOutOfBoundsException - if off is negative, if len is negative, or if off + len is greater than b.length