mq5.0-source.main.comm-io.src.main.java.com.sun.messaging.jmq.io.JMQByteBufferOutputStream Maven / Gradle / Ivy
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/*
* @(#)JMQByteBufferOutputStream.java 1.3 06/27/07
*/
package com.sun.messaging.jmq.io;
import java.io.OutputStream;
import java.io.IOException;
import java.io.EOFException;
import java.nio.ByteBuffer;
import java.nio.BufferOverflowException;
/**
* This class implements an output stream in which the data is
* written into a ByteBuffer. The buffer is provided by the
* caller, and it does NOT grow.
* The data can be retrieved using getByteBuffer()
*
*/
public class JMQByteBufferOutputStream extends OutputStream {
/**
* The buffer where data is stored.
*/
protected ByteBuffer buf = null;
/**
* Flag indicating whether the stream has been closed.
*/
private boolean isClosed = false;
/** Check to make sure that the stream has not been closed */
private void ensureOpen() {
/* This method does nothing for now. Once we add throws clauses
* to the I/O methods in this class, it will throw an IOException
* if the stream has been closed.
*/
}
/**
* Creates a new byte buffer output stream using the specified
* ByteBuffer as the backing store. The buffer is used
* exactly "as-is". It is not copied, duplicated or sliced.
* Writes to the output stream will start writing to the buffer
* at its current position. The buffer's position will be updated
* as data is written to the output stream.
* If the buffer fills up, it is not re-allocated.
*/
public JMQByteBufferOutputStream(ByteBuffer buf) {
this.buf = buf;
}
/**
* Writes the specified byte to this byte buffer output stream.
* If the backing buffer fills up an BufferOverflowException is thrown
* (i.e. the
* buffer does not grow). The backing buffer's position is updated.
*
* @param b the byte to be written.
*/
public synchronized void write(int b)
throws BufferOverflowException {
ensureOpen();
buf.put((byte)b);
}
/**
* Writes len bytes from the specified byte array
* starting at offset off to this byte array output stream.
* If the backing buffer fills up an EOFException is thrown (i.e. the
* buffer does not grow). The backing buffer's position is updated.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
*/
public synchronized void write(byte b[], int off, int len)
throws BufferOverflowException {
ensureOpen();
if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
}
buf.put(b, off, len);
}
/**
* Clears the backing buffer so that all currently accumulated output
* in the output stream is disgarded. The output stream can be
* used again, reusing the already allocated buffer space.
*
* @see java.io.ByteArrayInputStream#count
*/
public synchronized void reset() {
ensureOpen();
buf.clear();
}
/**
* Return the backing-store byte buffer. The exact buffer is returned.
* It is NOT a copy, slice or duplicate. The buffer's position will
* is whatever the current position is.
*
* @return the current contents of this output stream, as a ByteBuffer
*/
public synchronized ByteBuffer getByteBuffer() {
return buf;
}
/**
* Returns the current size of the buffer.
*
* @return the ByteBuffer's capacity, which is the number
* of valid bytes in this output stream.
*/
public int size() {
return buf.capacity();
}
/**
* Closes this output stream and releases any system resources
* associated with this stream. A closed stream cannot perform
* output operations and cannot be reopened.
*
*
*/
public synchronized void close() throws IOException {
isClosed = true;
buf = null;
}
}