Class BASE64DecoderStream

java.lang.Object
java.io.InputStream
java.io.FilterInputStream
org.jvnet.mimepull.BASE64DecoderStream
All Implemented Interfaces:
Closeable, AutoCloseable
final class BASE64DecoderStream extends FilterInputStream
This class implements a BASE64 Decoder. It is implemented as a FilterInputStream, so one can just wrap this class around any input stream and read bytes from this filter. The decoding is done as the bytes are read out.

  • Field Details

    • buffer

      private byte[] buffer

    • bufsize

      private int bufsize

    • index

      private int index

    • input_buffer

      private byte[] input_buffer

    • input_pos

      private int input_pos

    • input_len

      private int input_len

    • ignoreErrors

      private boolean ignoreErrors

    • pem_array

      private static final char[] pem_array
      This character array provides the character to value map based on RFC1521.

    • pem_convert_array

      private static final byte[] pem_convert_array

  • Constructor Details

    • BASE64DecoderStream

      public BASE64DecoderStream(InputStream in)
      Create a BASE64 decoder that decodes the specified input stream. The System property mail.mime.base64.ignoreerrors controls whether errors in the encoded data cause an exception or are ignored. The default is false (errors cause exception).
      Parameters:
      in - the input stream

    • BASE64DecoderStream

      public BASE64DecoderStream(InputStream in, boolean ignoreErrors)
      Create a BASE64 decoder that decodes the specified input stream.
      Parameters:
      in - the input stream
      ignoreErrors - ignore errors in encoded data?

  • Method Details

    • read

      public int read() throws IOException
      Read the next decoded byte from this input stream. The byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.
      Overrides:
      read in class FilterInputStream
      Returns:
      next byte of data, or -1 if the end of the stream is reached.
      Throws:
      IOException - if an I/O error occurs.
      See Also:

    • read

      public int read(byte[] buf, int off, int len) throws IOException
      Reads up to len decoded bytes of data from this input stream into an array of bytes. This method blocks until some input is available.
      Overrides:
      read in class FilterInputStream
      Parameters:
      buf - the buffer into which the data is read.
      off - the start offset of the data.
      len - the maximum number of bytes read.
      Returns:
      the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
      Throws:
      IOException - if an I/O error occurs.

    • skip

      public long skip(long n) throws IOException
      Skips over and discards n bytes of data from this stream.
      Overrides:
      skip in class FilterInputStream
      Throws:
      IOException

    • markSupported

      public boolean markSupported()
      Tests if this input stream supports marks. Currently this class does not support marks
      Overrides:
      markSupported in class FilterInputStream

    • available

      public int available() throws IOException
      Returns the number of bytes that can be read from this input stream without blocking. However, this figure is only a close approximation in case the original encoded stream contains embedded CRLFs; since the CRLFs are discarded, not decoded
      Overrides:
      available in class FilterInputStream
      Throws:
      IOException

    • decode

      private int decode(byte[] outbuf, int pos, int len) throws IOException
      The decoder algorithm. Most of the complexity here is dealing with error cases. Returns the number of bytes decoded, which may be zero. Decoding is done by filling an int with 4 6-bit values by shifting them in from the bottom and then extracting 3 8-bit bytes from the int by shifting them out from the bottom.
      Parameters:
      outbuf - the buffer into which to put the decoded bytes
      pos - position in the buffer to start filling
      len - the number of bytes to fill
      Returns:
      the number of bytes filled, always a multiple of three, and may be zero
      Throws:
      IOException - if the data is incorrectly formatted

    • getByte

      private int getByte() throws IOException
      Read the next valid byte from the input stream. Buffer lots of data from underlying stream in input_buffer, for efficiency.
      Returns:
      the next byte, -1 on EOF, or -2 if next byte is '=' (padding at end of encoded data)
      Throws:
      IOException

    • recentChars

      private String recentChars()
      Return the most recent characters, for use in an error message.

    • decode

      public static byte[] decode(byte[] inbuf)
      Base64 decode a byte array. No line breaks are allowed. This method is suitable for short strings, such as those in the IMAP AUTHENTICATE protocol, but not to decode the entire content of a MIME part. NOTE: inbuf may only contain valid base64 characters. Whitespace is not ignored.