import java.io.*;

class Test{
    public static void main(String agrs[]){
        FileReader fr = null;
        FileWriter fw = null;
        BufferedReader br = null;   
        BufferedWriter bw = null;
        try{
            fr = new FileReader("C:/Users/Administrator/Desktop/运行代码/from.txt");
            fw = new FileWriter("C:/Users/Administrator/Desktop/运行代码/to.txt");
            br = new BufferedReader(fr);
            bw = new BufferedWriter(fw);
            
            String line = null;
            while(true){
                line = br.readLine();
                if(line == null){
                    break;
                }
                System.out.println(line);    //这个有显示
                bw.write(line);              //就是这里了，不知道是什么问题
            }
        }
        catch(Exception e){
            System.out.println(e);
        }    
        finally{
            try{
                fw.close();
                br.close();
                fr.close();   
                br.close();
            }
            catch(Exception e){
                System.out.println(e);
            }
        }
    }
}