如何对一个XOR文件解异或

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class MyFileUtils {

    public static void xorDec(File srcfile,File desfile,byte xorchar) throws IOException{
        FileInputStream fis = new FileInputStream(srcfile);
        FileOutputStream fos = new FileOutputStream(desfile);
        
        byte[] bs = new byte[1024];
        
        int len = 0;
        while((len = fis.read(bs))!= -1){
            
            for(int i = 0 ;i < len ;i++){
                
                bs[i]^=xorchar;
                
            }
            fos.write(bs,0,len);
            
        }
        fis.close();
        fos.close();
        
        
    }
    
}