以下代码实际解决了我的所有任务，包括所需的输出：

# Convert binary string to hex digits.

def bin_to_hex(s)
  s.each_byte.map { |b| b.to_s(16).rjust(2, '0') }.join
end

# Convers hex string to binary string.

def hex_to_bin(s)
  s.scan(/../).map { |x| x.hex.chr }.join
end

# HBase special 'convert and print' routine to get hex digits, process them and print.

def print_hex_to_bin(s)
  Kernel.print "\"" + Bytes.toStringBinary(s.scan(/../).map { |x| x.hex.chr }.join.to_java_bytes) + "\"\n"
end

主要基于http://anthonylewis.com/2011/02/09/to-hex-and-back-with-ruby/