I/O flow study notes

I/O flow study notes

The essence of streaming is the transmission of data

1. File class ①Create
   a File class
   File file = new File (file path); ②Get
   the name of the file file.getName(); ③Create a file file.createNewFile(); ④Judge whether the file exists file.exists(); ⑤ Create a folder file.mkdir() : Create a multi-level directory folder file.mkdirs();
   
   
   
   
   
   
   
   
   

2. Byte stream FileInputStream and FileOutputStrem (read unit is byte)
   ① Read file FileInputStrem
   FileInputStream fileInputStream = new FileInputStream(file);
   int i = fileInputStream.read();
   while (i> 0){ System.out.println(( char)i); i = fileInputStream.read(); }
   
   
   

   // 以上读取文件的效率偏低
   FileInputStream fileInputStream = new FileInputStream(file);
   byte[] bytes = new byte[1024];  //1kb
   
   // 表示一次读取1kb
   int read = fileInputStream.read(bytes);
   // 对获得的数据进行数据转换
   String s = new String(bytes);
   ② 写入文本 FileOutputStrem
   FileOutputStream fileOutputStream = new FileOutputStream("F:/b.txt");
   fileOutputStream.write(写入的内容);
   

3. Character stream Reader

   // Reader implementation class

    ① InputStremReader （传入的参数 是char）
    FileInputStream fileInputStream = new FileInputStream(file);
            //获取字符输入流 （需要传入一个字节流）
    InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream,"gbk");
    
            char[] c = new char[64];
            // 传入一个64位的char
            int read = inputStreamReader.read(c);
            System.out.println( new String(c));
            
    ② FileReader（相比上面，不需传入字节流和编码格式）
    FileReader fileReader = new FileReader(file);
     char[] c = new char[64];
            // 传入一个64位的char
            int read = inputStreamReader.read(c);
            System.out.println( new String(c));
            
    ③ BufferedReader（使用BufferedReader读取文本内容可以保证文本内容的格式不被打乱 ：：缓冲流）
    
    		 FileInputStream fileInputStream = new FileInputStream(file);
            //获取字符输入流
            InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
   
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String line = null;
            while ((line=bufferedReader.readLine())!= null){
                System.out.println(line);
            }
   

// Finally note: a stream needs to be closed after use, otherwise some operations cannot be completed