Package com.compomics.util.io.file

Class MonitorableInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

com.compomics.util.io.file.MonitorableInputStream

All Implemented Interfaces:

Monitorable, Closeable, AutoCloseable

Direct Known Subclasses:

MonitorableFileInputStream

public class MonitorableInputStream
extends FilterInputStream
implements Monitorable

This class provides a specific FilterInputStream that can be monitored for progress. It is expected to be a bit slower than a regular InputStream, albeit not very much (typical difference compared with only regular FileInputStream for reading a file of appr. 20MB with a wrapped BufferedReader is undetectable).

Author:

Lennart Martens

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor	Description
MonitorableInputStream(InputStream aIn)	A MonitorableInputStream can only be constructed around an existing InputStream.
MonitorableInputStream(InputStream aIn, boolean aBypassCache)	A MonitorableInputStream can only be constructed around an existing InputStream.
MonitorableInputStream(InputStream aIn, int aMaximum)	A MonitorableInputStream can only be constructed around an existing InputStream.

Method Summary

Modifier and Type	Method	Description
int	getMaximum()	This method reports on the total amount of bytes that can be read from the monitored InputStream.
int	monitorProgress()	This method returns the progress (as measured by taking the value of iMaximum, minus the current available bytes as reported by the underlying InputStream - variable iRemainder).
int	read()	Reads the next byte of data from this input stream.
int	read(byte[] b)	Reads up to byte.length bytes of data from this input stream into an array of bytes.
int	read(byte[] b, int off, int len)	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 n)	Skips over and discards n bytes of data from the input stream.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported

Methods inherited from class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo

Methods inherited from class java.lang.Object

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

Constructor Details

MonitorableInputStream

public MonitorableInputStream(InputStream aIn)
                       throws IOException

A MonitorableInputStream can only be constructed around an existing InputStream. This InputStream will be the one monitored.

Parameters:

aIn - InputStream to monitor.

Throws:

IOException - when something is wrong with the InpuStream.

MonitorableInputStream

public MonitorableInputStream(InputStream aIn,
 int aMaximum)
                       throws IOException

A MonitorableInputStream can only be constructed around an existing InputStream. This InputStream will be the one monitored. This constructor allows the setting of the maximum readsize. It is useful when monitoring certain files, which cannot report on the available bytes.

Parameters:

aIn - InputStream to monitor.

aMaximum - int with the maximum number of bytes that can be read.

Throws:

IOException - when something is wrong with the InpuStream.

MonitorableInputStream

public MonitorableInputStream(InputStream aIn,
 boolean aBypassCache)
                       throws IOException

A MonitorableInputStream can only be constructed around an existing InputStream. This InputStream will be the one monitored. This constructor can instruct the instance to bypass the progress cache and update the information directly. This is useful when monitoring read progress in zipfiles, which cannot report on the available bytes, and whose underlying streams are masked by a PushBackInputStream.

Parameters:

aIn - InputStream to monitor.

aBypassCache - boolean that indicates whether the cache should be bypassed.

Throws:

IOException - when something is wrong with the InpuStream.

Method Details

getMaximum

public int getMaximum()

This method reports on the total amount of bytes that can be read from the monitored InputStream.

Specified by:

getMaximum in interface Monitorable

Returns:

int with the total bytes that can be read from the InputStream.

monitorProgress

public int monitorProgress()

This method returns the progress (as measured by taking the value of iMaximum, minus the current available bytes as reported by the underlying InputStream - variable iRemainder).

Specified by:

monitorProgress in interface Monitorable

Returns:

int with the progress.

read

public int read(byte[] b)
         throws IOException

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.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is 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:

IOException - if an I/O error occurs.

See Also:

• FilterInputStream.read(byte[], int, int)

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 simply performs in.read() and returns the result.

Overrides:

read in class FilterInputStream

Returns:

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

Throws:

IOException - if an I/O error occurs.

See Also:

• FilterInputStream.in

read

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

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.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - 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:

IOException - if an I/O error occurs.

See Also:

• FilterInputStream.in

skip

public long skip(long n)
          throws IOException

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).

Overrides:

skip in class FilterInputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs.

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.

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.

Overrides:

reset in class FilterInputStream

Throws:

IOException - if the stream has not been marked or if the mark has been invalidated.

See Also:

• FilterInputStream.in
• FilterInputStream.mark(int)