TXT文件编码转换例子
import java.io.File;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;

public class TranslateCharset {
static public void main(String args[]) throws Exception {
String inFilename = "inputFileName.txt";
String inFileCharsetName = "InputFileCharSetName";
String outFilename = "outputFileName.txt";
String outFileCharsetName = "OutputFileCharSetName";

File infile = new File(inFilename);
File outfile = new File(outFilename);

RandomAccessFile inraf = new RandomAccessFile(infile, "r");
RandomAccessFile outraf = new RandomAccessFile(outfile, "rw");

FileChannel finc = inraf.getChannel();
FileChannel foutc = outraf.getChannel();

MappedByteBuffer inmbb = finc.map(FileChannel.MapMode.READ_ONLY, 0, (int) infile.length());

Charset inCharset = Charset.forName(inFileCharsetName);
Charset outCharset = Charset.forName(outFileCharsetName);

CharsetDecoder inDecoder = inCharset.newDecoder();
CharsetEncoder outEncoder = outCharset.newEncoder();

CharBuffer cb = inDecoder.decode(inmbb);
ByteBuffer outbb = outEncoder.encode(cb);

foutc.write(outbb);

inraf.close();
outraf.close();
}
}