com.bbn.openmap.io
Class StreamInputReader

java.lang.Object
  com.bbn.openmap.io.StreamInputReader

All Implemented Interfaces:

InputReader

Direct Known Subclasses:

ByteArrayInputReader, JarInputReader, URLInputReader

public abstract class StreamInputReader
extends java.lang.Object
implements InputReader

An Abstract InputReader to handle reading data from streams, where seeking to a place in the file in front of the current pointer involves closing the stream, and re-seeking from the beginning.

See Also:

InputReader, BinaryFile

Field Summary

protected java.io.InputStream	inputStream The underlying data input stream, for resource files.
protected long	inputStreamCount Keep track of how many bytes have been read when using the DataInputStream to read the file.
protected java.lang.String	name The source name.

Constructor Summary

StreamInputReader()

Method Summary

long	available() Return how many bytes the input stream thinks are available.
void	close() Closes the underlying file
protected int	count(int add) Add the number of bytes to the inputStreamCount.
long	getFilePointer() Get the index of the next character to be read
java.lang.String	getName() Get the name of the source.
long	length() Return how many bytes the input stream thinks make up the file.
int	read() Read from the file.
int	read(byte[] b) Read from the file.
int	read(byte[] b, int off, int len) Read from the file
byte[]	readBytes(int howmany, boolean allowless) Read from the file.
protected void	reopen() Reset the DataInputStream to the beginning, by closing the current connection and reopening it.
void	seek(long pos) Set the index of the next character to be read.
long	skipBytes(long n) Skip over n bytes in the input file

Methods inherited from class java.lang.Object

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

Field Detail

inputStream

protected java.io.InputStream inputStream

The underlying data input stream, for resource files. Is used if the inputFile is null.

inputStreamCount

protected long inputStreamCount

Keep track of how many bytes have been read when using the DataInputStream to read the file.

name

protected java.lang.String name

The source name.

Constructor Detail

StreamInputReader

public StreamInputReader()

Method Detail

getName

public java.lang.String getName()

Description copied from interface: InputReader

Get the name of the source.

Specified by:

getName in interface InputReader

count

protected int count(int add)

Add the number of bytes to the inputStreamCount.

Returns:

number of bytes added in this call, to pass along to anything else that will be interested.

reopen

protected void reopen()
               throws java.io.IOException

Reset the DataInputStream to the beginning, by closing the current connection and reopening it. The StreamInputReader method simply closes the input stream and resets the input stream count, so the implementation of this class needs to reopen the stream at the beginning of the source file.

Throws:

java.io.IOException

skipBytes

public long skipBytes(long n)
               throws java.io.IOException

Skip over n bytes in the input file

Specified by:

skipBytes in interface InputReader

Parameters:

n - the number of bytes to skip

Returns:

the actual number of bytes skipped. annoying, isn't it?

Throws:

java.io.IOException - Any IO errors that occur in skipping bytes in the underlying file

getFilePointer

public long getFilePointer()
                    throws java.io.IOException

Get the index of the next character to be read

Specified by:

getFilePointer in interface InputReader

Returns:

the index

Throws:

java.io.IOException - Any IO errors that occur in accessing the underlying file

seek

public void seek(long pos)
          throws java.io.IOException

Set the index of the next character to be read.

Specified by:

seek in interface InputReader

Parameters:

pos - the position to seek to.

Throws:

java.io.IOException - Any IO Errors that occur in seeking the underlying file.

length

public long length()
            throws java.io.IOException

Return how many bytes the input stream thinks make up the file. This is calculated by adding the number of bytes read to the number of bytes available. May not be reliable.

Specified by:

length in interface InputReader

Returns:

the number of bytes remaining to be read (counted in bytes)

Throws:

java.io.IOException - Any IO errors encountered in accessing the file

available

public long available()
               throws java.io.IOException

Return how many bytes the input stream thinks are available.

Specified by:

available in interface InputReader

Returns:

the number of bytes remaining to be read (counted in bytes)

Throws:

java.io.IOException - Any IO errors encountered in accessing the file

close

public void close()
           throws java.io.IOException

Closes the underlying file

Specified by:

close in interface InputReader

Throws:

java.io.IOException - Any IO errors encountered in accessing the file

read

public int read()
         throws java.io.IOException

Read from the file.

Specified by:

read in interface InputReader

Returns:

one byte from the file. -1 for EOF

Throws:

java.io.IOException - Any IO errors encountered in reading from the file

read

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

Read from the file

Specified by:

read in interface InputReader

Parameters:

b - The byte array to read into

off - the first array position to read into

len - the number of bytes to read

Returns:

the number of bytes read

Throws:

java.io.IOException - Any IO errors encountered in reading from the file

read

public int read(byte[] b)
         throws java.io.IOException

Read from the file.

Specified by:

read in interface InputReader

Parameters:

b - the byte array to read into. Equivalent to read(b, 0, b.length)

Returns:

the number of bytes read

Throws:

java.io.IOException - Any IO errors encountered in reading from the file

See Also:

RandomAccessFile.read(byte[])

readBytes

public byte[] readBytes(int howmany,
                        boolean allowless)
                 throws java.io.EOFException,
                        FormatException

Read from the file.

Specified by:

readBytes in interface InputReader

Parameters:

howmany - the number of bytes to read

allowless - if we can return fewer bytes than requested

Returns:

the array of bytes read.

Throws:

FormatException - Any IO Exceptions, plus an end-of-file encountered after reading some, but now enough, bytes when allowless was false

java.io.EOFException - Encountered an end-of-file while allowless was false, but NO bytes had been read.