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Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class FilterOutputStream - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.io
Class FilterOutputStream

java.lang.Object
  |
  +--java.io.OutputStream
        |
        +--java.io.FilterOutputStream

Direct Known Subclasses:

BufferedOutputStream, CheckedOutputStream, DataOutputStream, DeflaterOutputStream, DigestOutputStream, PrintStream

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public class FilterOutputStream

extends OutputStream

This class is the superclass of all classes that filter output streams. These streams sit on top of an already existing output stream (the underlying output stream) which it uses as its basic sink of data, but possibly transforming the data along the way or providing additional functionality.

The class FilterOutputStream itself simply overrides all methods of OutputStream with versions that pass all requests to the underlying output stream. Subclasses of FilterOutputStream may further override some of these methods as well as provide additional methods and fields.

Since:

JDK1.0

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Field Summary
protected  OutputStream	out           The underlying output stream to be filtered.

 

Constructor Summary

FilterOutputStream(OutputStream out)           Creates an output stream filter built on top of the specified underlying output stream.

 

Method Summary
void	close()           Closes this output stream and releases any system resources associated with the stream.
void	flush()           Flushes this output stream and forces any buffered output bytes to be written out to the stream.
void	write(byte[] b)           Writes b.length bytes to this output stream.
void	write(byte[] b, int off, int len)           Writes len bytes from the specified byte array starting at offset off to this output stream.
void	write(int b)           Writes the specified byte to this output stream.

 

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

out

protected OutputStream out

The underlying output stream to be filtered.

Constructor Detail

FilterOutputStream

public FilterOutputStream(OutputStream out)

Creates an output stream filter built on top of the specified underlying output stream.

Parameters:

out - the underlying output stream to be assigned to the field this.out for later use, or null if this instance is to be created without an underlying stream.

Method Detail

write

public void write(int b)
           throws IOException

Writes the specified byte to this output stream.

The write method of FilterOutputStream calls the write method of its underlying output stream, that is, it performs out.write(b).

Implements the abstract write method of OutputStream.

Overrides:

write in class OutputStream

Parameters:

b - the byte.

Throws:

IOException - if an I/O error occurs.

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write

public void write(byte[] b)
           throws IOException

Writes b.length bytes to this output stream.

The write method of FilterOutputStream calls its write method of three arguments with the arguments b, 0, and b.length.

Note that this method does not call the one-argument write method of its underlying stream with the single argument b.

Overrides:

write in class OutputStream

Parameters:

b - the data to be written.

Throws:

IOException - if an I/O error occurs.

See Also:

write(byte[], int, int)

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write

public void write(byte[] b,
                  int off,
                  int len)
           throws IOException

Writes len bytes from the specified byte array starting at offset off to this output stream.

The write method of FilterOutputStream calls the write method of one argument on each byte to output.

Note that this method does not call the write method of its underlying input stream with the same arguments. Subclasses of FilterOutputStream should provide a more efficient implementation of this method.

Overrides:

write in class OutputStream

Parameters:

b - the data.

off - the start offset in the data.

len - the number of bytes to write.

Throws:

IOException - if an I/O error occurs.

See Also:

write(int)

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flush

public void flush()
           throws IOException

Flushes this output stream and forces any buffered output bytes to be written out to the stream.

The flush method of FilterOutputStream calls the flush method of its underlying output stream.

Overrides:

flush in class OutputStream

Throws:

IOException - if an I/O error occurs.

See Also:

out

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close

public void close()
           throws IOException

Closes this output stream and releases any system resources associated with the stream.

The close method of FilterOutputStream calls its flush method, and then calls the close method of its underlying output stream.

Overrides:

close in class OutputStream

Throws:

IOException - if an I/O error occurs.

See Also:

flush(), out

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