try {
            FileReader f = new FileReader("c:/a.txt");
            BufferedReader br = new BufferedReader(f);
            String read = br.readLine();
            while(read != null){
                System.out.println(read);
                read = br.readLine();
                if(br.markSupported()){
                    if(read.equals("511111")){
                        System.out.println("标记位置在511111");
                        br.mark(0);
                    }
                    
                    if(read.equals("911111")){
                        System.out.println("读取到这行返回到标记位置循环读取");
                        br.reset();
                    }
                }
            }
            br.close();
            f.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }