NIO基本（1）

1. FileChannel

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class SimpleChannel {
	private static String SOURCE_PATH = "d:/aa/aa.txt";
	private static String CLONE_PATH = "d:/bb/bb.txt";
	
	public static void main(String[] args) throws Exception {
		FileInputStream fis = new FileInputStream(new File(SOURCE_PATH));
		FileChannel fcInput = fis.getChannel();
		
		FileOutputStream fos = new FileOutputStream(new File(CLONE_PATH));
		FileChannel fcOutput = fos.getChannel();
		
		ByteBuffer dst = ByteBuffer.allocate(1024);
		while(true) {
			// before read clear()
			dst.clear();
			if(fcInput.read(dst) == -1) {
				break;
			}
			System.out.print(new String(dst.array()));
			
			// before write flip()
			dst.flip();
			fcOutput.write(dst);
			
		}
		fos.flush();
		fcInput.close();
		fcOutput.close();
		fis.close();
		fos.close();
	}
}

还可以使用下面方式进行操作，在FileChannel中有两个特殊方法可以允许我们直接将两个通道相连：
long transferFrom(ReadableByteChannel src, long position, long count);
long transferTo(long position, long count, WriteableByteChannel targets);
另外
java.nio.channels.Channels类中提供了实用方法，可以在通道中产生Reader和Writer
Reader和Writer可以通过 Channels.newReader(); Channels.newWriter();

2. Charset 字符集

Charset.forName(charCode).newDecoder().decode(buffer).toString();