再看NIO

1.文件复制

	public static void method6() throws IOException {
		try {
			FileInputStream fis = new FileInputStream("D:\\var\\demo.txt");
			FileOutputStream fos = new FileOutputStream("D:\\var\\demo3.txt");
			FileChannel readChannel = fis.getChannel();
			FileChannel writerChannel = fos.getChannel();
			ByteBuffer buffer = ByteBuffer.allocate(0124);
			while(true) {
				buffer.clear();
				int len = readChannel.read(buffer);
				if(len == -1)
					break;
				buffer.flip();
				writerChannel.write(buffer);
			}
			readChannel.close();
			writerChannel.close();
			System.out.println("over");
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

2.buffer的创建的两种方式

		ByteBuffer buffer1 = ByteBuffer.allocate(0124);
		
		byte[] arr = new byte[1024];
		ByteBuffer buffer2 = ByteBuffer.wrap(arr);

3.buffer重置

	rewind（）	clear（）	flip（）
position	置零	置零	置零
mark	清空	清空	清空
limit	未改动	设置为capacity	设置为position
作用	为读取buffer中有效数据做准备	为重新写入buffer做准备	在读写切换时调用

4.读写缓冲区

5.标志缓冲区

6.复制缓冲区

7.缓冲区分片

8.只读缓冲区

9.文件映射到内存

	public static void method7() throws IOException {
		RandomAccessFile raf = new RandomAccessFile("D:\\\\var\\\\demo.txt", "rw");
		FileChannel fc = raf.getChannel();
		MappedByteBuffer mbb = fc.map(FileChannel.MapMode.READ_WRITE, 0, raf.length());
		while(mbb.hasRemaining())
			System.out.println((char)mbb.get());
	}

10.处理结构化数据

11.直接内存访问

ByteBuffer buffer = ByteBuffer.allocateDirect(1024);