java.io.FilterInputStream Maven / Gradle / Ivy
/*
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documentation, such as a unified set of documents of API signatures for
a platform that includes technologies expressed as Java APIs. The file
may also be used to produce "compilation stubs," which allow
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Any work generated from this file, such as unified javadocs or compiled
stub files, must be accompanied by this notice in its entirety.
This work corresponds to the API signatures of JSR 219: Foundation
Profile 1.1. In the event of a discrepency between this work and the
JSR 219 specification, which is available at
http://www.jcp.org/en/jsr/detail?id=219, the latter takes precedence.
*/
package java.io;
/**
* A FilterInputStream contains
* some other input stream, which it uses as
* its basic source of data, possibly transforming
* the data along the way or providing additional
* functionality. The class FilterInputStream
* itself simply overrides all methods of
* InputStream with versions that
* pass all requests to the contained input
* stream. Subclasses of FilterInputStream
* may further override some of these methods
* and may also provide additional methods
* and fields.
*
* @author Jonathan Payne
* @version 1.23, 02/02/00
* @since JDK1.0
*/
public class FilterInputStream extends InputStream
{
/**
* The input stream to be filtered.
*/
protected InputStream in;
/**
* Creates a FilterInputStream
* by assigning the argument in
* to the field this.in so as
* to remember it for later use.
*
* @param in the underlying input stream, or null if
* this instance is to be created without an underlying stream.
*/
protected FilterInputStream(InputStream in) { }
/**
* Reads the next byte of data from this input stream. The value
* byte is returned as an int in the range
* 0 to 255. If no byte is available
* because the end of the stream has been reached, the value
* -1 is returned. This method blocks until input data
* is available, the end of the stream is detected, or an exception
* is thrown.
*
* This method
* simply performs in.read() and returns the result.
*
* @return the next byte of data, or -1 if the end of the
* stream is reached.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public int read() throws IOException {
return 0;
}
/**
* Reads up to byte.length bytes of data from this
* input stream into an array of bytes. This method blocks until some
* input is available.
*
* This method simply performs the call
* read(b, 0, b.length) and returns
* the result. It is important that it does
* not do in.read(b) instead;
* certain subclasses of FilterInputStream
* depend on the implementation strategy actually
* used.
*
* @param b the buffer into which the data is read.
* @return the total number of bytes read into the buffer, or
* -1 if there is no more data because the end of
* the stream has been reached.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#read(byte[], int, int)
*/
public int read(byte[] b) throws IOException {
return 0;
}
/**
* Reads up to len bytes of data from this input stream
* into an array of bytes. This method blocks until some input is
* available.
*
* This method simply performs in.read(b, off, len)
* and returns the result.
*
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* -1 if there is no more data because the end of
* the stream has been reached.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public int read(byte[] b, int off, int len) throws IOException {
return 0;
}
/**
* Skips over and discards n bytes of data from the
* input stream. The skip method may, for a variety of
* reasons, end up skipping over some smaller number of bytes,
* possibly 0. The actual number of bytes skipped is
* returned.
*
* This method
* simply performs in.skip(n).
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
*/
public long skip(long n) throws IOException {
return -1;
}
/**
* Returns the number of bytes that can be read from this input
* stream without blocking.
*
* This method
* simply performs in.available() and
* returns the result.
*
* @return the number of bytes that can be read from the input stream
* without blocking.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public int available() throws IOException {
return 0;
}
/**
* Closes this input stream and releases any system resources
* associated with the stream.
* This
* method simply performs in.close().
*
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public void close() throws IOException { }
/**
* Marks the current position in this input stream. A subsequent
* call to the reset method repositions this stream at
* the last marked position so that subsequent reads re-read the same bytes.
*
* The readlimit argument tells this input stream to
* allow that many bytes to be read before the mark position gets
* invalidated.
*
* This method simply performs in.mark(readlimit).
*
* @param readlimit the maximum limit of bytes that can be read before
* the mark position becomes invalid.
* @see java.io.FilterInputStream#in
* @see java.io.FilterInputStream#reset()
*/
public synchronized void mark(int readlimit) { }
/**
* Repositions this stream to the position at the time the
* mark method was last called on this input stream.
*
* This method
* simply performs in.reset().
*
* Stream marks are intended to be used in
* situations where you need to read ahead a little to see what's in
* the stream. Often this is most easily done by invoking some
* general parser. If the stream is of the type handled by the
* parse, it just chugs along happily. If the stream is not of
* that type, the parser should toss an exception when it fails.
* If this happens within readlimit bytes, it allows the outer
* code to reset the stream and try another parser.
*
* @exception IOException if the stream has not been marked or if the
* mark has been invalidated.
* @see java.io.FilterInputStream#in
* @see java.io.FilterInputStream#mark(int)
*/
public synchronized void reset() throws IOException { }
/**
* Tests if this input stream supports the mark
* and reset methods.
* This method
* simply performs in.markSupported().
*
* @return true if this stream type supports the
* mark and reset method;
* false otherwise.
* @see java.io.FilterInputStream#in
* @see java.io.InputStream#mark(int)
* @see java.io.InputStream#reset()
*/
public boolean markSupported() {
return false;
}
}