文本文件的转码复制

有个名叫fgbk的文件，里面有gbk格式的“abc中”
16进制为 61 62 63 D6 D0
现在需要复制转换成目标文件futf8
16进制为 61 62 63 E4 B8 AD

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Scanner;

public class fileCopyChangeCode {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("原文件");
        String from = sc.nextLine();
        System.out.println("目标文件");
        String to = sc.nextLine();
        System.out.println("原文件编码");
        String fromCharset = sc.nextLine();
        System.out.println("目标文件编码");
        String toCharset = sc.nextLine();
        try {
            copy(from, to, fromCharset, toCharset);
            System.out.println("复制转码完成!");
        } catch (IOException e) {
            e.printStackTrace();
        }
        sc.close();
    }

    private static void copy(String from, String to, String fromCharset, String toCharset) throws IOException {
        InputStreamReader in = new InputStreamReader(new FileInputStream(from),fromCharset);
        OutputStreamWriter out = new OutputStreamWriter(new FileOutputStream(to),toCharset);
        char buff[] =new char[8192];
        int n;
        while((n=in.read(buff))!=-1)
                {
            out.write(buff,0,n);
                }
        in.close();
        out.close();
    }
}

运行结果

原文件
fgbk
目标文件
futf8
原文件编码
gbk
目标文件编码
utf8
复制转码完成!