Class StreamUtils

java.lang.Object
org.springframework.util.StreamUtils
public abstract class StreamUtils extends Object
Simple utility methods for dealing with streams.

The copy methods of this class are similar to those defined in FileCopyUtils except that all affected streams are left open when done. All copy methods use a block size of 8192 bytes.

Mainly for use within the framework, but also useful for application code.

Since:
3.2.2
Author:
Juergen Hoeller, Phillip Webb, Brian Clozel
See Also:

  • Field Details

    • BUFFER_SIZE

      public static final int BUFFER_SIZE
      The default buffer size used when copying bytes.
      See Also:

  • Constructor Details

    • StreamUtils

      public StreamUtils()

  • Method Details

    • copyToByteArray

      public static byte[] copyToByteArray(@Nullable InputStream in) throws IOException
      Copy the contents of the given InputStream into a new byte array.

      Leaves the stream open when done.

      Parameters:
      in - the stream to copy from (may be null or empty)
      Returns:
      the new byte array that has been copied to (possibly empty)
      Throws:
      IOException - in case of I/O errors

    • copyToString

      public static String copyToString(@Nullable InputStream in, Charset charset) throws IOException
      Copy the contents of the given InputStream into a String.

      Leaves the stream open when done.

      Parameters:
      in - the InputStream to copy from (may be null or empty)
      charset - the Charset to use to decode the bytes
      Returns:
      the String that has been copied to (possibly empty)
      Throws:
      IOException - in case of I/O errors

    • copyToString

      public static String copyToString(ByteArrayOutputStream baos, Charset charset)
      Copy the contents of the given ByteArrayOutputStream into a String.

      This is a more effective equivalent of new String(baos.toByteArray(), charset).

      Parameters:
      baos - the ByteArrayOutputStream to be copied into a String
      charset - the Charset to use to decode the bytes
      Returns:
      the String that has been copied to (possibly empty)
      Since:
      5.2.6

    • copy

      public static void copy(byte[] in, OutputStream out) throws IOException
      Copy the contents of the given byte array to the given OutputStream.

      Leaves the stream open when done.

      Parameters:
      in - the byte array to copy from
      out - the OutputStream to copy to
      Throws:
      IOException - in case of I/O errors

    • copy

      public static void copy(String in, Charset charset, OutputStream out) throws IOException
      Copy the contents of the given String to the given OutputStream.

      Leaves the stream open when done.

      Parameters:
      in - the String to copy from
      charset - the Charset
      out - the OutputStream to copy to
      Throws:
      IOException - in case of I/O errors

    • copy

      public static int copy(InputStream in, OutputStream out) throws IOException
      Copy the contents of the given InputStream to the given OutputStream.

      Leaves both streams open when done.

      Parameters:
      in - the InputStream to copy from
      out - the OutputStream to copy to
      Returns:
      the number of bytes copied
      Throws:
      IOException - in case of I/O errors

    • copyRange

      public static long copyRange(InputStream in, OutputStream out, long start, long end) throws IOException
      Copy a range of content of the given InputStream to the given OutputStream.

      If the specified range exceeds the length of the InputStream, this copies up to the end of the stream and returns the actual number of copied bytes.

      Leaves both streams open when done.

      Parameters:
      in - the InputStream to copy from
      out - the OutputStream to copy to
      start - the position to start copying from
      end - the position to end copying
      Returns:
      the number of bytes copied
      Throws:
      IOException - in case of I/O errors
      Since:
      4.3

    • drain

      public static int drain(@Nullable InputStream in) throws IOException
      Drain the remaining content of the given InputStream.

      Leaves the InputStream open when done.

      Parameters:
      in - the InputStream to drain
      Returns:
      the number of bytes read, or 0 if the supplied InputStream is null or empty
      Throws:
      IOException - in case of I/O errors
      Since:
      4.3

    • emptyInput

      @Deprecated(since="6.0") public static InputStream emptyInput()
      Deprecated.
      as of 6.0 in favor of InputStream.nullInputStream()
      Return an efficient empty InputStream.
      Returns:
      an InputStream which contains no bytes
      Since:
      4.2.2

    • nonClosing

      public static InputStream nonClosing(InputStream in)
      Return a variant of the given InputStream where calling close() has no effect.
      Parameters:
      in - the InputStream to decorate
      Returns:
      a version of the InputStream that ignores calls to close

    • nonClosing

      public static OutputStream nonClosing(OutputStream out)
      Return a variant of the given OutputStream where calling close() has no effect.
      Parameters:
      out - the OutputStream to decorate
      Returns:
      a version of the OutputStream that ignores calls to close