com.pdd.pop.ext.glassfish.grizzly.FileTransfer Maven / Gradle / Ivy
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package com.pdd.pop.ext.glassfish.grizzly;
import com.pdd.pop.ext.glassfish.grizzly.asyncqueue.WritableMessage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;
/**
* A simple class that abstracts {@link FileChannel#transferTo(long, long, java.nio.channels.WritableByteChannel)}
* for use with Grizzly 2.0 {@link com.pdd.pop.ext.glassfish.grizzly.asyncqueue.AsyncQueueWriter}.
*
* @since 2.2
*/
public class FileTransfer implements WritableMessage {
private FileChannel fileChannel;
private long len;
private long pos;
// ------------------------------------------------------------ Constructors
/**
* Constructs a new FileTransfer instance backed by the specified
* {@link File}. This simply calls this(f, 0, f.length).
*
* @param f the {@link File} to transfer.
*
* @throws NullPointerException if f is null.
*
* @see #FileTransfer(java.io.File, long, long)
*/
public FileTransfer(final File f) {
this(f, 0, f.length());
}
/**
* Constructs a new FileTransfer instance backed by the specified
* {@link File}. The content to transfer will begin at the specified offset,
* pos with the total transfer length being specified by
* len.
*
* @param f the {@link File} to transfer.
* @param pos the offset within the File to start the transfer.
* @param len the total number of bytes to transfer.
*
* @throws IllegalArgumentException if f is null, does not exist, is
* not readable, or is a directory.
* @throws IllegalArgumentException if pos or len
* are negative.
* @throws IllegalArgumentException if len exceeds the number of bytes that
* may be transferred based on the provided offset and file length.
*/
public FileTransfer(final File f, final long pos, final long len) {
if (f == null) {
throw new IllegalArgumentException("f cannot be null.");
}
if (!f.exists()) {
throw new IllegalArgumentException("File " + f.getAbsolutePath() + " does not exist.");
}
if (!f.canRead()) {
throw new IllegalArgumentException("File " + f.getAbsolutePath() + " is not readable.");
}
if (f.isDirectory()) {
throw new IllegalArgumentException("File " + f.getAbsolutePath() + " is a directory.");
}
if (pos < 0) {
throw new IllegalArgumentException("The pos argument cannot be negative.");
}
if (len < 0) {
throw new IllegalArgumentException("The len argument cannot be negative.");
}
if (pos > f.length()) {
throw new IllegalArgumentException("Illegal offset");
}
if (f.length() - pos < len) {
throw new IllegalArgumentException("Specified length exceeds available bytes to transfer.");
}
this.pos = pos;
this.len = len;
try {
fileChannel = new FileInputStream(f).getChannel();
} catch (FileNotFoundException fnfe) {
throw new IllegalStateException(fnfe);
}
}
// ---------------------------------------------------------- Public Methods
/**
* Transfers the File backing this FileTransfer to the specified
* {@link WritableByteChannel}.
*
* @param c the {@link WritableByteChannel}
* @return
* @throws IOException
*/
public long writeTo(final WritableByteChannel c) throws IOException {
final long written = fileChannel.transferTo(pos, len, c);
pos += written;
len -= written;
return written;
}
// ------------------------------------------ Methods from WritableMessage
/**
* {@inheritDoc}
*/
@Override
public boolean hasRemaining() {
return (len != 0);
}
/**
* {@inheritDoc}
*/
@Override
public int remaining() {
return ((len > Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int) len);
}
/**
* {@inheritDoc}
*/
@Override
public boolean release() {
try {
fileChannel.close();
} catch (IOException ignored) {
} finally {
fileChannel = null;
}
return true;
}
/**
* {@inheritDoc}
*/
@Override
public boolean isExternal() {
return true;
}
}