This class does not define methods for opening existing files or for creating
new ones; such methods may be added in a future release. In this release a
file channel can be obtained from an existing FileInputStream,
FileOutputStream, or RandomAccessFile object by invoking that object's
getChannel method, which returns a file channel that is connected to the
same underlying file.
ということみたいです。
つまり、FileInputStreamやFileOutputStream,RandomAccessFileのメソッドである
getChannel()を呼び出して、FileChannelを利用するという形を
現状は使うそうです。