com.peterphi.std.crypto.digest.LengthDigester Maven / Gradle / Ivy
package com.peterphi.std.crypto.digest;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.ByteChannel;
/**
* A digest algorithm which takes the length of the data as its digest
*/
class LengthDigester implements IDigester
{
private static LengthDigester instance;
public static LengthDigester getInstance()
{
if (instance == null)
instance = new LengthDigester();
return instance;
}
/**
* LengthDigester
* Use the static getInstance method
*/
private LengthDigester()
{
}
@Override
public String digest(byte[] content)
{
return Integer.toString(content.length);
}
@Override
public String digest(File file) throws IOException
{
return Long.toString(file.length());
}
@Override
public String digest(InputStream is) throws IOException
{
return Long.toString(getSize(is));
}
@Override
public String digest(ByteChannel channel) throws IOException
{
return Long.toString(getSize(channel));
}
private long getSize(final InputStream is) throws IOException
{
long size = 0;
try
{
final byte[] buffer = new byte[4096];
int readSize;
while ((readSize = is.read(buffer)) != -1)
{
size += readSize;
}
}
finally
{
is.close();
}
return size;
}
private long getSize(final ByteChannel channel) throws IOException
{
long size = 0;
try
{
final ByteBuffer buffer = ByteBuffer.allocateDirect(8192);
while (channel.read(buffer) >= 0)
{
size += buffer.limit();
buffer.clear();
}
}
finally
{
channel.close();
}
return size;
}
}