Package org.apache.commons.codec.binary

Class Base64OutputStream

java.lang.Object
java.io.OutputStream
java.io.FilterOutputStream
org.apache.commons.codec.binary.BaseNCodecOutputStream
org.apache.commons.codec.binary.Base64OutputStream
All Implemented Interfaces:
Closeable, Flushable, AutoCloseable
public class Base64OutputStream extends BaseNCodecOutputStream
Provides Base64 encoding and decoding in a streaming fashion (unlimited size). When encoding the default lineLength is 76 characters and the default lineEnding is CRLF, but these can be overridden by using the appropriate constructor.

The default behavior of the Base64OutputStream is to ENCODE, whereas the default behavior of the Base64InputStream is to DECODE. But this behavior can be overridden by using a different constructor.

This class implements section 6.8. Base64 Content-Transfer-Encoding from RFC 2045 Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies by Freed and Borenstein.

Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).

Note: It is mandatory to close the stream after the last byte has been written to it, otherwise the final padding will be omitted and the resulting data will be incomplete/inconsistent.

You can set the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a valid encoding. These can be bits that are unused from the final character or entire characters. The default mode is lenient decoding.

  • Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.
  • Strict: The decoding will raise an IllegalArgumentException if trailing bits are not part of a valid encoding. Any unused bits from the final character must be zero. Impossible counts of entire final characters are not allowed.

When strict decoding is enabled it is expected that the decoded bytes will be re-encoded to a byte array that matches the original, i.e. no changes occur on the final character. This requires that the input bytes use the same padding and alphabet as the encoder.

Since:
1.4
See Also:

  • Constructor Details

    • Base64OutputStream

      public Base64OutputStream(OutputStream outputStream)
      Constructs a Base64OutputStream such that all data written is Base64-encoded to the original provided OutputStream.
      Parameters:
      outputStream - OutputStream to wrap.

    • Base64OutputStream

      public Base64OutputStream(OutputStream outputStream, boolean doEncode)
      Constructs a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the original provided OutputStream.
      Parameters:
      outputStream - OutputStream to wrap.
      doEncode - true if we should encode all data written to us, false if we should decode.

    • Base64OutputStream

      public Base64OutputStream(OutputStream outputStream, boolean doEncode, int lineLength, byte[] lineSeparator)
      Constructs a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the original provided OutputStream.
      Parameters:
      outputStream - OutputStream to wrap.
      doEncode - true if we should encode all data written to us, false if we should decode.
      lineLength - If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to the nearest multiple of 4). If lineLength <= 0, the encoded data is not divided into lines. If doEncode is false, lineLength is ignored.
      lineSeparator - If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n). If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.

    • Base64OutputStream

      public Base64OutputStream(OutputStream outputStream, boolean doEncode, int lineLength, byte[] lineSeparator, CodecPolicy decodingPolicy)
      Constructs a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the original provided OutputStream.
      Parameters:
      outputStream - OutputStream to wrap.
      doEncode - true if we should encode all data written to us, false if we should decode.
      lineLength - If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to the nearest multiple of 4). If lineLength <= 0, the encoded data is not divided into lines. If doEncode is false, lineLength is ignored.
      lineSeparator - If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n). If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
      decodingPolicy - The decoding policy.
      Since:
      1.15