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 Details

    • 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.

      Java 9 users and later: this method should be treated as deprecated; use the equivalent InputStream.transferTo(java.io.OutputStream) method instead.

      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.

      Java 9+ users: use in#readAllBytes() instead.

      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 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

      public static ByteArrayDataInput newDataInput(byte[] bytes)
      Returns a new ByteArrayDataInput instance to read from the bytes array from the beginning.

    • newDataInput

      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

      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

      public static ByteArrayDataOutput newDataOutput()
      Returns a new ByteArrayDataOutput instance with a default size.

    • newDataOutput

      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

      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

      public static OutputStream nullOutputStream()
      Returns an OutputStream that simply discards written bytes.

      Java 11+ users: use OutputStream.nullOutputStream() instead. Note that the ByteStreams method returns a singleton stream whose close method has no effect, while the OutputStream method returns a new instance whose write methods throw if called on a closed stream.

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

    • limit

      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

      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

      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

      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

      @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

      @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