[java][nio]convert text to and from ByteBuffer

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
/**
 * 
 * convert text to and from ByteBuffer
 *
 */
public class Buffer2Text {

	private static final int BSIZE = 1024;
	private static final String FILE_NAME = "d:\\a.txt";
	public static void main(String[] args) throws Exception {
		
		FileChannel fc = new FileOutputStream(FILE_NAME).getChannel();
		fc.write(ByteBuffer.wrap("中国人".getBytes()));
		fc.close();
		
		fc = new FileInputStream(FILE_NAME).getChannel();
		ByteBuffer bb = ByteBuffer.allocate(BSIZE);
		fc.read(bb);
		bb.flip();
		//乱码
		System.out.println(bb.asCharBuffer());
		
		//使用系统默认字符集编码进行解码
		bb.rewind();//指针返回到数据开始部分
		String encoding = System.getProperty("file.encoding");
		System.out.println("Decoded using " + encoding + ": " + Charset.forName(encoding).decode(bb));
		fc.close();
		
		//如果使用将要输出的字符集进行编码
		fc = new FileOutputStream(FILE_NAME).getChannel();
		fc.write(ByteBuffer.wrap("中国人".getBytes("UTF-16BE")));
		fc.close();
		
		//再输出的时候就OK
		fc = new FileInputStream(FILE_NAME).getChannel();
		bb.clear();
		fc.read(bb);
		bb.flip();
		System.out.println("--: " + bb.asCharBuffer());
		fc.close();
		
		//使用CharBuffer来写
		fc = new FileOutputStream(FILE_NAME).getChannel();
		//这里的size将决定输出bb.asCharBuffer()的大小
		//一个字符两个字节，多出的字节也会打印，如果分配的空间不够，则会抛出异常
		bb = ByteBuffer.allocate(6);
		bb.asCharBuffer().put("外国人");
		fc.write(bb);
		fc.close();
		
		//读出
		fc = new FileInputStream(FILE_NAME).getChannel();
		bb.clear();
		fc.read(bb);
		bb.flip();
		System.out.println("++: " + bb.asCharBuffer());
        fc.close();
	}

}