com.helger.commons.io.stream

Class NonBlockingPushbackInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

com.helger.commons.io.stream.WrappedInputStream

com.helger.commons.io.stream.NonBlockingPushbackInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class NonBlockingPushbackInputStream
extends WrappedInputStream

A non-synchronized copy of the class PushbackInputStream.

Author:

Philip Helger

See Also:

PushbackInputStream

Field Summary

Fields

Modifier and Type	Field and Description
protected byte[]	m_aBuf The pushback buffer.
protected int	m_nBufPos The position within the pushback buffer from which the next byte will be read.

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor and Description
NonBlockingPushbackInputStream(InputStream aIS) Creates a PushbackInputStream and saves its argument, the input stream in, for later use.
NonBlockingPushbackInputStream(InputStream aIS, int nSize) Creates a PushbackInputStream with a pushback buffer of the specified size, and saves its argument, the input stream in, for later use.

Method Summary

Modifier and Type	Method and Description
int	available() Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.
void	close() Closes this input stream and releases any system resources associated with the stream.
int	getUnreadCount()
boolean	hasUnreadBytes()
void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the mark and reset methods, which it does not.
int	read() Reads the next byte of data from this input stream.
int	read(byte[] aBuf, int nOfs, int nLen) Reads up to len bytes of data from this input stream into an array of bytes.
void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long nSkip) Skips over and discards n bytes of data from this input stream.
void	unread(byte[] aBuf) Pushes back an array of bytes by copying it to the front of the pushback buffer.
void	unread(byte[] aBuf, int nOfs, int nLen) Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer.
void	unread(int b) Pushes back a byte by copying it to the front of the pushback buffer.

Methods inherited from class com.helger.commons.io.stream.WrappedInputStream

getWrappedInputStream, toString

Methods inherited from class java.io.FilterInputStream

read

Methods inherited from class java.lang.Object

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

Field Detail

m_aBuf

protected byte[] m_aBuf

The pushback buffer.

Since:

JDK1.1

m_nBufPos

protected int m_nBufPos

The position within the pushback buffer from which the next byte will be read. When the buffer is empty, pos is equal to buf.length; when the buffer is full, pos is equal to zero.

Since:

JDK1.1

Constructor Detail

NonBlockingPushbackInputStream

public NonBlockingPushbackInputStream(@Nonnull
                                      InputStream aIS,
                                      @Nonnegative
                                      int nSize)

Creates a PushbackInputStream with a pushback buffer of the specified size, and saves its argument, the input stream in, for later use. Initially, there is no pushed-back byte (the field pushBack is initialized to -1).

Parameters:

aIS - the input stream from which bytes will be read.

nSize - the size of the pushback buffer.

Throws:

IllegalArgumentException - if size is ≤ 0

Since:

JDK1.1

NonBlockingPushbackInputStream

public NonBlockingPushbackInputStream(@Nonnull
                                      InputStream aIS)

Creates a PushbackInputStream and saves its argument, the input stream in, for later use. Initially, there is no pushed-back byte (the field pushBack is initialized to -1).

Parameters:

aIS - the input stream from which bytes will be read.

Method Detail

getUnreadCount

@Nonnegative
public int getUnreadCount()

Returns:

The number of bytes currently in the "unread" buffer.

hasUnreadBytes

public boolean hasUnreadBytes()

Returns:

true if at least one "unread" byte is present.

read

public int read()
         throws IOException

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 returns the most recently pushed-back byte, if there is one, and otherwise calls the read method of its underlying input stream and returns whatever value that method returns.

Overrides:

read in class FilterInputStream

Returns:

the next byte of data, or -1 if the end of the stream has been reached.

Throws:

IOException - if this input stream has been closed by invoking its close() method, or an I/O error occurs.

See Also:

InputStream.read()

read

public int read(@Nonnull
                byte[] aBuf,
                @Nonnegative
                int nOfs,
                @Nonnegative
                int nLen)
         throws IOException

Reads up to len bytes of data from this input stream into an array of bytes. This method first reads any pushed-back bytes; after that, if fewer than len bytes have been read then it reads from the underlying input stream. If len is not zero, the method blocks until at least 1 byte of input is available; otherwise, no bytes are read and 0 is returned.

Overrides:

read in class FilterInputStream

Parameters:

aBuf - the buffer into which the data is read.

nOfs - the start offset in the destination array b

nLen - the maximum number of bytes read.

Returns:

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.

Throws:

NullPointerException - If b is null.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off

IOException - if this input stream has been closed by invoking its close() method, or an I/O error occurs.

See Also:

InputStream.read(byte[], int, int)

unread

public void unread(int b)
            throws IOException

Pushes back a byte by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value (byte)b.

Parameters:

b - the int value whose low-order byte is to be pushed back.

Throws:

IOException - If there is not enough room in the pushback buffer for the byte, or this input stream has been closed by invoking its close() method.

unread

public void unread(@Nonnull
                   byte[] aBuf,
                   @Nonnegative
                   int nOfs,
                   @Nonnegative
                   int nLen)
            throws IOException

Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value b[off], the byte after that will have the value b[off+1], and so forth.

Parameters:

aBuf - the byte array to push back.

nOfs - the start offset of the data.

nLen - the number of bytes to push back.

Throws:

IOException - If there is not enough room in the pushback buffer for the specified number of bytes, or this input stream has been closed by invoking its close() method.

Since:

JDK1.1

unread

public void unread(@Nonnull
                   byte[] aBuf)
            throws IOException

Pushes back an array of bytes by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value b[0], the byte after that will have the value b[1], and so forth.

Parameters:

aBuf - the byte array to push back

Throws:

IOException - If there is not enough room in the pushback buffer for the specified number of bytes, or this input stream has been closed by invoking its close() method.

Since:

JDK1.1

available

public int available()
              throws IOException

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream. The next invocation might be the same thread or another thread. A single read or skip of this many bytes will not block, but may read or skip fewer bytes.

The method returns the sum of the number of bytes that have been pushed back and the value returned by available.

Overrides:

available in class FilterInputStream

Returns:

the number of bytes that can be read (or skipped over) from the input stream without blocking.

Throws:

IOException - if this input stream has been closed by invoking its close() method, or an I/O error occurs.

See Also:

InputStream.available()

skip

public long skip(long nSkip)
          throws IOException

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly zero. If n is negative, no bytes are skipped.

The skip method of PushbackInputStream first skips over the bytes in the pushback buffer, if any. It then calls the skip method of the underlying input stream if more bytes need to be skipped. The actual number of bytes skipped is returned.

Overrides:

skip in class FilterInputStream

Parameters:

nSkip - The number of bytes to skip. Must be ≥ 0.

Returns:

The number of bytes actually skipped

Throws:

IOException - if the stream does not support seek, or the stream has been closed by invoking its close() method, or an I/O error occurs.

Since:

1.2

See Also:

InputStream.skip(long n)

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods, which it does not.

Overrides:

markSupported in class FilterInputStream

Returns:

false, since this class does not support the mark and reset methods.

See Also:

InputStream.mark(int), InputStream.reset()

mark

public void mark(int readlimit)

Marks the current position in this input stream.

The mark method of PushbackInputStream does nothing.

Overrides:

mark in class FilterInputStream

Parameters:

readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

See Also:

InputStream.reset()

reset

public void reset()
           throws IOException

Repositions this stream to the position at the time the mark method was last called on this input stream.

The method reset for class PushbackInputStream does nothing except throw an IOException.

Overrides:

reset in class FilterInputStream

Throws:

IOException - if this method is invoked.

See Also:

InputStream.mark(int), IOException

close

public void close()
           throws IOException

Closes this input stream and releases any system resources associated with the stream. Once the stream has been closed, further read(), unread(), available(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class FilterInputStream

Throws:

IOException - if an I/O error occurs.