Java 文件字节字符数据转换

package io;
//: io/BufferToText.java
//Converting text to and from ByteBuffers
import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;
import java.io.*;
/*
 * 转换数据：
 * 缓冲器容纳的是普通的字节，为了把他们转换成字符，要么在输入的时候对其进行解码，要么将其从缓冲器输出时对他们进行解码。*/
public class BufferToText {
private static final int BSIZE = 1024;
public static void main(String[] args) throws Exception {

 FileChannel fc = new FileOutputStream("data2.txt").getChannel();
 fc.write(ByteBuffer.wrap("Some text".getBytes()));
 fc.close();
 fc = new FileInputStream("data2.txt").getChannel();
 ByteBuffer buff = ByteBuffer.allocate(BSIZE);
 fc.read(buff);
 buff.flip();
 // Doesn't work:
 System.out.println(buff.asCharBuffer());
 // Decode using this system's default Charset:
 buff.rewind();
 String encoding = System.getProperty("file.encoding");
 System.out.println("Decoded using " + encoding + ": " + Charset.forName(encoding).decode(buff));
 // Or, we could encode with something that will print:
 fc = new FileOutputStream("data2.txt").getChannel();
 fc.write(ByteBuffer.wrap("Some text".getBytes("UTF-16BE")));
 fc.close();
 // Now try reading again:
 fc = new FileInputStream("data2.txt").getChannel();
 buff.clear();
 fc.read(buff);
 buff.flip();
 System.out.println(buff.asCharBuffer());
 // Use a CharBuffer to write through:
 fc = new FileOutputStream("data2.txt").getChannel();
 buff = ByteBuffer.allocate(24); // More than needed
 buff.asCharBuffer().put("Some text");
 fc.write(buff);
 fc.close();
 // Read and display:
 fc = new FileInputStream("data2.txt").getChannel();
 buff.clear();
 fc.read(buff);
 buff.flip();
 System.out.println(buff.asCharBuffer());
}
}