The basic read() method reads a byte at a time. This
is less than perfectly efficient. The following two overloaded
variants read multiple bytes into an array of bytes.
public int read(byte[] data) throws IOException
public int read(byte[] data, int offset, int length)
throws IOException
The first method tries to read enough bytes to fill the array
data. The second method reads length bytes
from the input stream and stores them into the array data
starting at position offset.
These methods block until there is some data available. Then
they read as many bytes as they can into data, or until
they've read length bytes.
These methods then return the number of bytes actually read. You
should not assume that the array will be filled or that length bytes will actually have been read. If the end of
stream is encountered, -1 is returned.