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package javax.mail.util;
import java.io.*;
import javax.mail.internet.SharedInputStream;
/**
* A ByteArrayInputStream that implements the SharedInputStream interface,
* allowing the underlying byte array to be shared between multiple readers.
*
* @author Bill Shannon
* @since JavaMail 1.4
*/
public class SharedByteArrayInputStream extends ByteArrayInputStream
implements SharedInputStream {
/**
* Position within shared buffer that this stream starts at.
*/
protected int start = 0;
/**
* Create a SharedByteArrayInputStream representing the entire
* byte array.
*
* @param buf the byte array
*/
public SharedByteArrayInputStream(byte[] buf) {
super(buf);
}
/**
* Create a SharedByteArrayInputStream representing the part
* of the byte array from <code>offset</code> for <code>length</code>
* bytes.
*
* @param buf the byte array
* @param offset offset in byte array to first byte to include
* @param length number of bytes to include
*/
public SharedByteArrayInputStream(byte[] buf, int offset, int length) {
super(buf, offset, length);
start = offset;
}
/**
* Return the current position in the InputStream, as an
* offset from the beginning of the InputStream.
*
* @return the current position
*/
public long getPosition() {
return pos - start;
}
/**
* Return a new InputStream representing a subset of the data
* from this InputStream, starting at <code>start</code> (inclusive)
* up to <code>end</code> (exclusive). <code>start</code> must be
* non-negative. If <code>end</code> is -1, the new stream ends
* at the same place as this stream. The returned InputStream
* will also implement the SharedInputStream interface.
*
* @param start the starting position
* @param end the ending position + 1
* @return the new stream
*/
public InputStream newStream(long start, long end) {
if (start < 0)
throw new IllegalArgumentException("start < 0");
if (end == -1)
end = count - this.start;
return new SharedByteArrayInputStream(buf,
this.start + (int)start, (int)(end - start));
}
}