Package org.apache.commons.codec.binary

Class Base64InputStream

java.lang.Object
java.io.InputStream
java.io.FilterInputStream
org.apache.commons.codec.binary.BaseNCodecInputStream
org.apache.commons.codec.binary.Base64InputStream
All Implemented Interfaces:
Closeable, AutoCloseable
public class Base64InputStream extends BaseNCodecInputStream
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 Base64InputStream is to DECODE, whereas the default behavior of the Base64OutputStream is to ENCODE, 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).

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

    • Base64InputStream

      public Base64InputStream(InputStream inputStream)
      Creates a Base64InputStream such that all data read is Base64-decoded from the original provided InputStream.
      Parameters:
      inputStream - InputStream to wrap.

    • Base64InputStream

      public Base64InputStream(InputStream inputStream, boolean doEncode)
      Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original provided InputStream.
      Parameters:
      inputStream - InputStream to wrap.
      doEncode - true if we should encode all data read from us, false if we should decode.

    • Base64InputStream

      public Base64InputStream(InputStream inputStream, boolean doEncode, int lineLength, byte[] lineSeparator)
      Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original provided InputStream.
      Parameters:
      inputStream - InputStream to wrap.
      doEncode - true if we should encode all data read from 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.

    • Base64InputStream

      public Base64InputStream(InputStream inputStream, boolean doEncode, int lineLength, byte[] lineSeparator, CodecPolicy decodingPolicy)
      Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original provided InputStream.
      Parameters:
      inputStream - InputStream to wrap.
      doEncode - true if we should encode all data read from 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