NIO的基本应用

对文件进行读写：

package dqd.io;
import java.io.BufferedInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import org.omg.CORBA.Request;
/**
 * NIO入门
 * @author dqd
 */
public class TestIO {
	public static void main(String[] args) throws IOException  {
		RandomAccessFile aFile = new RandomAccessFile("log/sys.out.txt", "rw");
		FileChannel inChannel = aFile.getChannel();
		ByteBuffer buf = ByteBuffer.allocate(48);
		int size = inChannel.read(buf);
		
		System.out.println(size);
		int totalSize = (int) inChannel.size();
		String newData = "New String to write to file..." + System.currentTimeMillis();
		buf = ByteBuffer.allocate(148);
		buf.put(newData.getBytes());
		buf.flip();
		//将可能存在缓冲区的数据强制的放入磁盘上
		inChannel.force(true);
		//一个汉字两个字节
		inChannel.position(totalSize);
		while(buf.hasRemaining()){
			inChannel.write(buf);
		}
		//注意关闭
		inChannel.close();
	}
}