[java][nio]三种流获得可写/可读可写/可读的通道

import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;/** *  * 从流中获得通道 * FileInputStream, FileOutputStream, RandomAccessFile * */public class GetChannel {private static final int BSIZE = 1024;public static void main(String[] args) throws IOException {//写文件FileChannel fc = new FileOutputStream("d:\\a.txt").getChannel();fc.write(ByteBuffer.wrap("This is a test for nio.\n".getBytes()));fc.close();//向文件末尾添加数据fc = new RandomAccessFile("d:\\a.txt","rw").getChannel();//定位到文件末尾fc.position(fc.size());fc.write(ByteBuffer.wrap("This is the end of file.".getBytes()));fc.close();//读文件fc = new FileInputStream("D:\\a.txt").getChannel();ByteBuffer bb = ByteBuffer.allocate(BSIZE);fc.read(bb);//转换缓冲开关，由读转为写bb.flip();while(bb.hasRemaining()){System.out.print((char)bb.get());}fc.close();}}