1.Scatter  从一个Channel读取的信息分散到N个缓冲区中(Buufer).

2.Gather  将N个Buffer里面内容按照顺序发送到一个Channel.  

    Scatter/Gather功能是通道(Channel)提供的  并不是Buffer,

Scatter/Gather相关接口 类图

    ReadableByteChannel WritableByteChannel     接口提供了通道的读写功能

    ScatteringByteChannel  GatheringByteChannel接口都新增了两个以缓冲区数组作为参数的相应方法

   以FileChannel为例

   *Scatter

/**	 * Scatter	 * 
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	 * @param fileName	 * @throws IOException	 * @see FileChannel.read(java.nio.ByteBuffer[])	 */	private static void scatter(final String fileName) throws IOException {		RandomAccessFile accessFile = new RandomAccessFile(fileName, "r");		//获取文件通道		FileChannel channel = accessFile.getChannel();		//创建两个缓冲区		ByteBuffer headBuffer = ByteBuffer.allocate(2);		ByteBuffer bodyBuffer = ByteBuffer.allocate(1024);				ByteBuffer[] allBuffers = new ByteBuffer[]{headBuffer, bodyBuffer};		// headBuffer 前10个字节		// bodyBuffer 剩下的 		long n = channel.read(allBuffers);		System.out.println("共读到多少字节:" + n);				headBuffer.flip();		//head缓冲区中的数据:qw		System.out.println("head缓冲区中的数据:" + charset.decode(headBuffer));				bodyBuffer.flip();		//body缓冲区中的数据:ertyuiop		System.out.println("body缓冲区中的数据:" + charset.decode(bodyBuffer));		accessFile.close();		channel.close();	}	/**	 * Scatter2	 * 
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	 * @param fileName	 * @throws IOException	 * @see FileChannel.read(java.nio.ByteBuffer[], int, int)	 */	private static void scatter2(final String fileName) throws IOException {		RandomAccessFile accessFile = new RandomAccessFile(fileName, "r");		//获取文件通道		FileChannel channel = accessFile.getChannel();		//创建五个缓冲区		ByteBuffer headBuffer = ByteBuffer.allocate(2);		ByteBuffer bodyBuffer1 = ByteBuffer.allocate(3);		ByteBuffer bodyBuffer2 = ByteBuffer.allocate(2);		ByteBuffer bodyBuffer3 = ByteBuffer.allocate(2);		ByteBuffer bodyBuffer4 = ByteBuffer.allocate(1);				ByteBuffer[] allBuffers = new ByteBuffer[]{				headBuffer, 				bodyBuffer1, bodyBuffer2,				bodyBuffer3, bodyBuffer4,};		//0从那个缓冲区开始被使用    使用3个缓冲区		//会使用 headBuffer,bodyBuffer1,bodyBuffer2		long n = channel.read(allBuffers, 0, 3);				System.out.println("共读到多少字节:" + n);				headBuffer.flip();		//head缓冲区中的数据:qw		System.out.println("head缓冲区中的数据:" + charset.decode(headBuffer));				bodyBuffer1.flip();		//body1缓冲区中的数据:ert		System.out.println("body1缓冲区中的数据:" + charset.decode(bodyBuffer1));				bodyBuffer2.flip();		//body2缓冲区中的数据:yu		System.out.println("body2缓冲区中的数据:" + charset.decode(bodyBuffer2));				bodyBuffer3.flip();		//body3，没有数据		System.out.println("body3缓冲区中的数据:" + charset.decode(bodyBuffer3));				bodyBuffer4.flip();		//body4没有数据		System.out.println("body4缓冲区中的数据:" + charset.decode(bodyBuffer4));				accessFile.close();		channel.close();	}		/**	 *	 * 
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	 * @param fileName	 * @throws IOException	 */	private static void writeData(final String fileName, String data) throws IOException {		RandomAccessFile accessFile = new RandomAccessFile(fileName, "rw");		accessFile.writeBytes(data);		accessFile.close();	}

private static Charset charset = Charset.forName("GBK");		public static void main(String[] args) throws IOException {		final String fileName = "D:/test.log";		//先写入10个字节数据 以便测试 scatter模式		writeData(fileName, "qwertyuiop");				/**----------Scatter------------*/		//read(java.nio.ByteBuffer[])		scatter(fileName);				//read(java.nio.ByteBuffer[], int, int)		scatter2(fileName);	}

*Gather

/**	 * gather	 * 
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	 * @param fileName	 * @throws IOException 	 * @see FileChannel#write(java.nio.ByteBuffer[])	 */	private static void gather(String fileName) throws IOException {		RandomAccessFile accessFile = new RandomAccessFile(fileName, "rw");		//获取文件通道		FileChannel channel = accessFile.getChannel();		//创建两个缓冲区		ByteBuffer headBuffer = ByteBuffer.allocate(3);		headBuffer.put("abc".getBytes());				ByteBuffer bodyBuffer = ByteBuffer.allocate(1024);		bodyBuffer.put("defg".getBytes());				ByteBuffer[] allBuffers = new ByteBuffer[]{headBuffer, bodyBuffer};				headBuffer.flip();		bodyBuffer.flip();				//将按allBuffers顺序  写入abcdefg		long n = channel.write(allBuffers);				System.out.println("共写入多少字节:" + n);				accessFile.close();		channel.close();	}		/**	 * gather2	 * 
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	 * @param fileName	 * @throws IOException 	 * @see FileChannel#write(java.nio.ByteBuffer[], int, int)	 */	private static void gather2(String fileName) throws IOException {		RandomAccessFile accessFile = new RandomAccessFile(fileName, "rw");		//获取文件通道		FileChannel channel = accessFile.getChannel();		//创建两个缓冲区		ByteBuffer headBuffer = ByteBuffer.allocate(3);		ByteBuffer bodyBuffer1 = ByteBuffer.allocate(4);		ByteBuffer bodyBuffer2 = ByteBuffer.allocate(20);		ByteBuffer bodyBuffer3 = ByteBuffer.allocate(20);		ByteBuffer bodyBuffer4 = ByteBuffer.allocate(20);				headBuffer.put("abc".getBytes());		bodyBuffer1.put("defg".getBytes());		bodyBuffer2.put("bnbnbnb".getBytes());		bodyBuffer3.put("zzz444".getBytes());				ByteBuffer[] allBuffers = new ByteBuffer[]{				headBuffer, 				bodyBuffer1, bodyBuffer2,				bodyBuffer3, bodyBuffer4,};				headBuffer.flip();		bodyBuffer1.flip();		bodyBuffer2.flip();		bodyBuffer3.flip();		bodyBuffer4.flip();				//将按allBuffers数组顺序使用两个缓冲区		//0从哪开始		//2使用几个		//当前使用headBuffer  bodyBuffer1		//最终写入abcdefg		long n = channel.write(allBuffers, 0, 2);				//应该返回7个字节		System.out.println("共写入多少字节:" + n);				accessFile.close();		channel.close();	}

private static Charset charset = Charset.forName("GBK");		public static void main(String[] args) throws IOException {		final String fileName = "D:/test.log";		/**----------Gather------------*/		//FileChannel#write(java.nio.ByteBuffer[])		gather(fileName);				//FileChannel#write(java.nio.ByteBuffer[], int, int)		gather2(fileName);	}