Java IO.pdf - Nguyen Dang Binh

public int read() throws IOException
public int read(byte[] data) throws IOException
public int read(byte[] data, int offset, int length) throws IOException
public long skip(long n) throws IOException
public int available() throws IOException
public void close() throws IOException
public synchronized void mark(int readlimit)
public synchronized void reset() throws IOException
public boolean markSupported()
For FilterOutputStream, these are:
Java I/O
public void write(int b) throws IOException
public void write(byte[] data) throws IOException
public void write(byte[] data, int offset, int length) throws IOException
public void flush() throws IOException
public void close() throws IOException
Each of these methods merely passes its arguments to the corresponding method in the
underlying stream. For example, the skip() method in FilterInputStream behaves like
this:
public long skip(long n) throws IOException {
in.skip(n);
}
The close() method in FilterOutputStream behaves like this:
public void close() throws IOException {
out.close();
}
Thus, closing a filter stream closes the underlying stream. You cannot close one filter stream
and then open up another on the same underlying stream, nor can you close one filter stream
in a chain but still read from the underlying stream or other streams in the chain. Attempts to
do so will throw IOExceptions. Once a stream is closed—no matter by which filter stream
it's chained to—it's closed for good.
Since the constructors are protected, you don't use these classes directly. Instead, you create
subclasses and use those. Since FilterOutputStream does not have a no-argument
constructor, it's essential to give all subclasses explicit constructors and use super() to
invoke the FilterOutputStream constructor. Your subclass will probably also want to
override the write(int b) and write(byte[] data, int offset, int length) methods to
perform its filtering. The write(byte[] data) method merely invokes write(data, 0,
data.length), so if you've overridden the three-argument write() method, you probably
don't need to also override write(byte[] data). Depending on circumstances, you may or
may not need to override some of the other methods.
The PrintableOutputStream class shown in Example 6.1 is an example subclass of
FilterOutputStream that truncates all data to the range of printable ASCII characters: byte
values 32-126, plus 9, 10, and 13 (tab, linefeed, and carriage return). Every time a byte in that
range is passed to write(), it is written onto the underlying output stream, out. Every time a
byte outside that range is passed to write(), a question mark is written onto the underlying
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