ucar.unidata.io.http

Class HTTPRandomAccessFile

java.lang.Object

ucar.unidata.io.RandomAccessFile

ucar.unidata.io.http.HTTPRandomAccessFile

All Implemented Interfaces:

java.io.Closeable, java.io.DataInput, java.io.DataOutput, java.lang.AutoCloseable, FileCacheable

public class HTTPRandomAccessFile
extends RandomAccessFile

Gives access to files over HTTP, using "Accept-Ranges" HTTP header to do random access. This version uses a single instance of HttpClient, following performance guidelines at http://jakarta.apache.org/commons/httpclient/performance.html Plus other improvements.

Field Summary

Fields

Modifier and Type	Field and Description
static int	defaultHTTPBufferSize
static int	maxHTTPBufferSize

Fields inherited from class ucar.unidata.io.RandomAccessFile

allFiles, BIG_ENDIAN, bigEndian, buffer, bufferStart, dataEnd, dataSize, debugAccess, debugLeaks, defaultBufferSize, endOfFile, file, fileChannel, filePosition, LITTLE_ENDIAN, location, openFiles, readonly, showOpen, showRead

Constructor Summary

Constructors

Constructor and Description
HTTPRandomAccessFile(java.lang.String url)
HTTPRandomAccessFile(java.lang.String url, int bufferSize)

Method Summary

Modifier and Type	Method and Description
void	close() Close the file, and release any associated system resources.
long	getLastModified() Always returns 0L, as we cannot easily determine the last time that a remote file was modified.
long	length() Get the length of the file.
protected int	read_(long pos, byte[] buff, int offset, int len) Read directly from file, without going through the buffer.
long	readToByteChannel(java.nio.channels.WritableByteChannel dest, long offset, long nbytes) Read nbytes bytes, at the specified file offset, send to a WritableByteChannel.

Methods inherited from class ucar.unidata.io.RandomAccessFile

acquire, acquire, eject, enableDefaultGlobalFileCache, flush, getAllFiles, getBufferSize, getDebugLeaks, getDebugNbytes, getDebugNseeks, getFilePointer, getGlobalFileCache, getLocation, getMaxOpenFileCount, getOpenFileCount, getOpenFiles, getRandomAccessFile, isAtEndOfFile, order, order, reacquire, read, read, read, readBoolean, readBuffer, readByte, readBytes, readBytes, readChar, readDouble, readDouble, readFloat, readFloat, readFully, readFully, readInt, readInt, readIntUnbuffered, readLine, readLong, readLong, readShort, readShort, readString, readStringMax, readUnsignedByte, readUnsignedShort, readUTF, release, searchForward, seek, setBufferSize, setDebugAccess, setDebugLeaks, setExtendMode, setFileCache, setGlobalFileCache, setMinLength, shutdown, skipBytes, skipBytes, toString, unread, write, write, write, writeBoolean, writeBoolean, writeByte, writeBytes, writeBytes, writeBytes, writeChar, writeChar, writeChars, writeDouble, writeDouble, writeFloat, writeFloat, writeInt, writeInt, writeLong, writeLong, writeShort, writeShort, writeUTF

Methods inherited from class java.lang.Object

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

Field Detail

defaultHTTPBufferSize

public static final int defaultHTTPBufferSize

See Also:

Constant Field Values

maxHTTPBufferSize

public static final int maxHTTPBufferSize

See Also:

Constant Field Values

Constructor Detail

HTTPRandomAccessFile

public HTTPRandomAccessFile(java.lang.String url)
                     throws java.io.IOException

Throws:

java.io.IOException

HTTPRandomAccessFile

public HTTPRandomAccessFile(java.lang.String url,
                            int bufferSize)
                     throws java.io.IOException

Throws:

java.io.IOException

Method Detail

close

public void close()
           throws java.io.IOException

Description copied from class: RandomAccessFile

Close the file, and release any associated system resources.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface FileCacheable

Overrides:

close in class RandomAccessFile

Throws:

java.io.IOException - if an I/O error occurrs.

read_

protected int read_(long pos,
                    byte[] buff,
                    int offset,
                    int len)
             throws java.io.IOException

Read directly from file, without going through the buffer. All reading goes through here or readToByteChannel;

Overrides:

read_ in class RandomAccessFile

Parameters:

pos - start here in the file

buff - put data into this buffer

offset - buffer offset

len - this number of bytes

Returns:

actual number of bytes read

Throws:

java.io.IOException - on io error

readToByteChannel

public long readToByteChannel(java.nio.channels.WritableByteChannel dest,
                              long offset,
                              long nbytes)
                       throws java.io.IOException

Description copied from class: RandomAccessFile

Read nbytes bytes, at the specified file offset, send to a WritableByteChannel. This will block until all bytes are read. This uses the underlying file channel directly, bypassing all user buffers.

Overrides:

readToByteChannel in class RandomAccessFile

Parameters:

dest - write to this WritableByteChannel.

offset - the offset in the file where copying will start.

nbytes - the number of bytes to read.

Returns:

the actual number of bytes read and transfered

Throws:

java.io.IOException - if an I/O error occurs.

length

public long length()
            throws java.io.IOException

Description copied from class: RandomAccessFile

Get the length of the file. The data in the buffer (which may not have been written the disk yet) is taken into account.

Overrides:

length in class RandomAccessFile

Returns:

the length of the file in bytes.

Throws:

java.io.IOException - if an I/O error occurrs.

getLastModified

public long getLastModified()

Always returns 0L, as we cannot easily determine the last time that a remote file was modified.

Specified by:

getLastModified in interface FileCacheable

Overrides:

getLastModified in class RandomAccessFile

Returns:

0L, always.