de.schlichtherle.io.rof
Class BufferedReadOnlyFile

java.lang.Object
  de.schlichtherle.io.rof.AbstractReadOnlyFile
      de.schlichtherle.io.rof.FilterReadOnlyFile
          de.schlichtherle.io.rof.BufferedReadOnlyFile

All Implemented Interfaces:

ReadOnlyFile

public class BufferedReadOnlyFile
extends FilterReadOnlyFile

A ReadOnlyFile implementation which provides buffered random read only access to another ReadOnlyFile.

Note: This class implements its own virtual file pointer. Thus, if you would like to access the underlying ReadOnlyFile again after you have finished working with an instance of this class, you should synchronize their file pointers using the pattern as described in FilterReadOnlyFile.

Version:

TrueZIP 6.7

Author:

Christian Schlichtherle

Field Summary

static int

WINDOW_LEN The default buffer length of the window to the file.

Fields inherited from class de.schlichtherle.io.rof.FilterReadOnlyFile

rof

Constructor Summary

BufferedReadOnlyFile(File file)
Creates a new instance of BufferedReadOnlyFile.

BufferedReadOnlyFile(File file, int windowLen)
Creates a new instance of BufferedReadOnlyFile.

BufferedReadOnlyFile(ReadOnlyFile rof)
Creates a new instance of BufferedReadOnlyFile.

BufferedReadOnlyFile(ReadOnlyFile rof, int windowLen)
Creates a new instance of BufferedReadOnlyFile.

Method Summary

void	close() Closes this read only file.
protected ReadOnlyFile	createReadOnlyFile(File file) A factory method called by the constructor to get a read only file to access the contents of the read only file.
long	getFilePointer()
long	length()
protected static long	max(long a, long b) Returns the greater parameter.
protected static long	min(long a, long b) Returns the smaller parameter.
int	read()
int	read(byte[] buf, int off, int len) Reads up to len bytes of data from this read only file into the given array.
void	seek(long fp) Sets the file pointer offset, measured from the beginning of this file, at which the next read occurs.

Methods inherited from class de.schlichtherle.io.rof.AbstractReadOnlyFile

read, readFully, readFully, skipBytes

Methods inherited from class java.lang.Object

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

Field Detail

WINDOW_LEN

public static final int WINDOW_LEN

The default buffer length of the window to the file.

See Also:

Constant Field Values

Constructor Detail

BufferedReadOnlyFile

public BufferedReadOnlyFile(File file)
                     throws NullPointerException,
                            FileNotFoundException,
                            IOException

Creates a new instance of BufferedReadOnlyFile.

Parameters:

file - The file to read.

Throws:

NullPointerException - If any of the parameters is null.

FileNotFoundException - If the file cannot get opened for reading.

IOException - On any other I/O related issue.

BufferedReadOnlyFile

public BufferedReadOnlyFile(File file,
                            int windowLen)
                     throws NullPointerException,
                            FileNotFoundException,
                            IOException

Creates a new instance of BufferedReadOnlyFile.

Parameters:

file - The file to read.

windowLen - The size of the buffer window in bytes.

Throws:

NullPointerException - If any of the parameters is null.

FileNotFoundException - If the file cannot get opened for reading.

IOException - On any other I/O related issue.

BufferedReadOnlyFile

public BufferedReadOnlyFile(ReadOnlyFile rof)
                     throws NullPointerException,
                            FileNotFoundException,
                            IOException

Creates a new instance of BufferedReadOnlyFile.

Parameters:

rof - The read only file to read.

Throws:

NullPointerException - If any of the parameters is null.

FileNotFoundException - If the file cannot get opened for reading.

IOException - On any other I/O related issue.

BufferedReadOnlyFile

public BufferedReadOnlyFile(ReadOnlyFile rof,
                            int windowLen)
                     throws NullPointerException,
                            FileNotFoundException,
                            IOException

Creates a new instance of BufferedReadOnlyFile.

Parameters:

rof - The read only file to read.

windowLen - The size of the buffer window in bytes.

Throws:

NullPointerException - If any of the parameters is null.

FileNotFoundException - If the file cannot get opened for reading.

IOException - On any other I/O related issue.

Method Detail

min

protected static final long min(long a,
                                long b)

Returns the smaller parameter.

max

protected static final long max(long a,
                                long b)

Returns the greater parameter.

createReadOnlyFile

protected ReadOnlyFile createReadOnlyFile(File file)
                                   throws IOException

A factory method called by the constructor to get a read only file to access the contents of the read only file. This method is only used if the constructor isn't called with a read only file as its parameter.

Throws:

FileNotFoundException - If the file cannot get opened for reading.

IOException - On any other I/O related issue.

length

public long length()
            throws IOException

Specified by:

length in interface ReadOnlyFile

Overrides:

length in class FilterReadOnlyFile

Throws:

IOException

getFilePointer

public long getFilePointer()
                    throws IOException

Specified by:

getFilePointer in interface ReadOnlyFile

Overrides:

getFilePointer in class FilterReadOnlyFile

Throws:

IOException

seek

public void seek(long fp)
          throws IOException

Description copied from interface: ReadOnlyFile

Sets the file pointer offset, measured from the beginning of this file, at which the next read occurs. Whether the offset may be set beyond the end of the file is up to the implementor. For example, the SimpleReadOnlyFile subclasses RandomAccessFile and passes "r" as a parameter to the superclass constructor. On the Windows platform, this implementation allows to seek past the end of file, but on the Linux platform it doesn't.

Specified by:

seek in interface ReadOnlyFile

Overrides:

seek in class FilterReadOnlyFile

Parameters:

fp - The offset position, measured in bytes from the beginning of the file, at which to set the file pointer.

Throws:

IOException - If pos is less than 0 or if an I/O error occurs.

read

public int read()
         throws IOException

Specified by:

read in interface ReadOnlyFile

Overrides:

read in class FilterReadOnlyFile

Throws:

IOException

read

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

Description copied from interface: ReadOnlyFile

Reads up to len bytes of data from this read only file into the given array. This method blocks until at least one byte of input is available.

Specified by:

read in interface ReadOnlyFile

Overrides:

read in class FilterReadOnlyFile

Parameters:

buf - The buffer to fill with data.

off - The start offset of the data.

len - The maximum number of bytes to read.

Returns:

The total number of bytes read, or -1 if there is no more data because the end of the file has been reached.

Throws:

IOException - On any I/O related issue.

close

public void close()
           throws IOException

Closes this read only file. As a side effect, this will set the reference to the underlying read only file (FilterReadOnlyFile.rof to null.

Specified by:

close in interface ReadOnlyFile

Overrides:

close in class FilterReadOnlyFile

Throws:

IOException