JAVA I/O之文件复制

有没有大佬告诉我这个不要了的代码插入区（就现在这句话的区域）怎么删掉。。。。。。。

        //一个字节一个字节的复制
        public static  void  fun() throws IOException {
            FileInputStream fis = new FileInputStream("F:/abc.txt");
            FileOutputStream fos = new FileOutputStream("F:/字节流复制（一个字节一个字节）.txt");
            int by = 0;
            while ((by=fis.read()) != -1) {
                fos.write(by);
            }
            fis.close();
            fos.close();
        }
        //1024字节数组复制（加入数组缓冲区）
        public  static void  fun1() throws IOException {
            FileInputStream fis = new FileInputStream("F:/abc.txt");
            FileOutputStream fos = new FileOutputStream("F:/字节流复制（1024字节数组）.txt");
            int len = 0;
            byte[] bytes =new byte[1024];
            while ((len=fis.read(bytes)) != -1) {
                fos.write(bytes,0,len);
            }
            fis.close();
            fos.close();
        }
        // 一个字节一个字节复制并用了缓冲流 
        public static   void  fun2() throws IOException {
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream("F:/abc.txt"));
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("F:/字节缓冲流复制（一个字节一个字节）.txt"));
    
            int by = 0;
            while ((by=bis.read()) != -1) {
                bos.write(by);
            }
            bos.close();
            bis.close();
        }
        // 1024字节数组复制并用了缓冲流 （加入数组缓冲区）
        public  static void  fun3() throws IOException {
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream("F:/abc.txt"));
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("F:/字节缓冲流复制（1024字节数组）.txt"));
            int len = 0;
            byte[] bytes =new byte[1024];
            while ((len=bis.read(bytes)) != -1) {
                bos.write(bytes,0,len);
            }
            bos.close();
            bis.close();
        }
        //字符缓冲流复制文（一行一行可保留格式）
        public  static void  fun4() throws IOException {
            FileInputStream fileInputStream = new FileInputStream("F:/abc.txt");
　　　　　　　//出现乱码问题的原因：文件的编码，系统的编码，java的默认编码有冲突。
　　　　　　  //假如我们用FileReader这些类来读取系统文件，它调用的字符编码是java默认的UTF-8，但是一般WINDOW的TXT默认是ANSI，而自己本机的中文编码是GBK
            InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream,"GBK");
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
              
            FileOutputStream fileOutputStream = new FileOutputStream("F:/字符缓冲流复制文件.txt");
            OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream,"GBK");
            BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
              
              String line = null;
            while (null != (line = bufferedReader.readLine())) {
                bufferedWriter.write(line);
                bufferedWriter.newLine();
            }
            
            if (bufferedWriter != null || outputStreamWriter != null || fileOutputStream != null) {
                bufferedWriter.close();
                outputStreamWriter.close();
                fileOutputStream.close();
            }
            if (bufferedReader != null || inputStreamReader != null || fileInputStream != null) {
                bufferedReader.close();
                inputStreamReader.close();
                fileInputStream.close();
            }     
        }

        //字节流（ByteArrayInputStream）当你资源不足够用时,选择BufferedOutputStream是最佳的选择, 当你选择快速完成一个作业时,可以选择ByteArrayOutputStream之类的输出流https://www.cnblogs.com/yixiu868/p/8144670.html
        public  static void  fun5() throws IOException {
              FileInputStream fileInputStream = new FileInputStream("F:/abc.txt");
            byte[] buffer = new byte[1024];
            int len = 0;
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            while ((len = fileInputStream.read(buffer)) != -1) {
                bos.write(buffer, 0, len);
            }
            bos.close();
            byte[] bytes = bos.toByteArray();
            FileOutputStream fileOutputStream = new FileOutputStream("F:/字节流（ByteArrayInputStream）.txt");
            fileOutputStream.write(bytes);
            
            if (fileOutputStream != null) {
                fileOutputStream.close();
            }
            if (fileInputStream != null) {
                fileInputStream.close();
            }
        }
          public static void main(String[] arg) throws IOException{
                     
            long start,end;
            start = System.currentTimeMillis();
            fun();
            end = System.currentTimeMillis();
            System.out.println("一个字节一个字节的复制（字节流）花费时间:" + (end - start) + "ms");
           
            start = System.currentTimeMillis();
            fun1();
            end = System.currentTimeMillis();
            System.out.println("1024字节数组复制（字节流）花费时间:" + (end - start) + "ms");
            
            start = System.currentTimeMillis();
            fun2();
            end = System.currentTimeMillis();
            System.out.println("一个字节一个字节的复制（缓冲流）花费时间:" + (end - start) + "ms");
            
            start = System.currentTimeMillis();
            fun3();
            end = System.currentTimeMillis();
            System.out.println("1024字节数组复制（缓冲流）花费时间:" + (end - start) + "ms");
            
            start = System.currentTimeMillis();
            fun4();
            end = System.currentTimeMillis();
            System.out.println("字符缓冲流复制文件花费时间:" + (end - start) + "ms");
            
            start = System.currentTimeMillis();
            fun5();
            end = System.currentTimeMillis();
            System.out.println("字节流（ByteArrayInputStream）花费时间:" + (end - start) + "ms");

          }

执行结果：

下图为IO中的字节流和字符流，每一种又分为相应的输入流和输出流。需了解的基础概念：字符流（Reader，Writer），字节流，缓冲流（Buffered）；使用时按照各自需求去搜寻对应相关资料即可。