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I/o instance operation

2022-07-27 12:21:00 【51CTO】

       
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I/O Example operation _ Copy file

1、 Copy file

       
       File 
       
       file
       
       =
       
       new 
       
       File(
       
       "d:/aa/0.jpg");
       
       File 
       
       toFile
       
       =
       
       new 
       
       File(
       
       "d:/aa/00.jpg");
       
       long 
       
       begin
       
       =
       
       System.
       
       currentTimeMillis();
       
       try {
       
       // Create a byte input stream   Used to read the contents of the original file 
       
       FileInputStream 
       
       fileInputStream
       
       =
       
       new 
       
       FileInputStream(
       
       file);
       
       // Create a byte output stream   Used to write the copied file 
       
       FileOutputStream 
       
       fileOutputStream
       
       =
       
       new 
       
       FileOutputStream(
       
       toFile);
       
       int 
       
       a;
       
       // Read from the input stream 
       
       while((
       
       a
       
       =
       
       fileInputStream.
       
       read())
       
       !=-
       
       1)
       
      {
       
       // Write it out through the output stream 
       
       fileOutputStream.
       
       write(
       
       a);
       
      }
       
       fileInputStream.
       
       close();
       
       fileOutputStream.
       
       close();
       
    } 
       
       catch (
       
       FileNotFoundException 
       
       e) {
       
       // TODO Auto-generated catch block
       
       e.
       
       printStackTrace();
       
    } 
       
       catch (
       
       IOException 
       
       e) {
       
       // TODO Auto-generated catch block
       
       e.
       
       printStackTrace();
       
    }
       
       long 
       
       end
       
       =
       
       System.
       
       currentTimeMillis();
       
       System.
       
       out.
       
       println(
       
       " Total replication time :"
       
       +(
       
       end
       
       -
       
       begin)
       
       +
       
       " millisecond ");
      
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I/O Example operation _ Copy file _02

When we use file stream , Write data directly to another file through the stream , Although the purpose of copying files can be achieved in this way, such operation is particularly rough and inelegant .

2、 Buffer stream copy file

       
       // Copy file with buffer stream 
       
       File 
       
       file
       
       =
       
       new 
       
       File(
       
       "d:/aa/0.jpg");
       
       File 
       
       toFile
       
       =
       
       new 
       
       File(
       
       "d:/aa/000.jpg");
       
       long 
       
       begin
       
       =
       
       System.
       
       currentTimeMillis();
       
       // Create buffer byte input stream  ( Be sure to have a byte input stream first )
       
       FileInputStream 
       
       fileInputStream;
       
       try {
       
       fileInputStream 
       
       = 
       
       new 
       
       FileInputStream(
       
       file);
       
       BufferedInputStream 
       
       bufferedInputStream
       
       =
       
       new 
       
       BufferedInputStream(
       
       fileInputStream);
       
       // Create buffered byte output stream 
       
       FileOutputStream 
       
       fileOutputStream
       
       =
       
       new 
       
       FileOutputStream(
       
       toFile);
       
       BufferedOutputStream 
       
       bufferedOutputStream
       
       =
       
       new 
       
       BufferedOutputStream(
       
       fileOutputStream);
       
       // Read data from the input stream   Write out from the output stream 
       
       int 
       
       a;
       
       while((
       
       a
       
       =
       
       bufferedInputStream.
       
       read())
       
       !=-
       
       1)
       
      {
       
       bufferedOutputStream.
       
       write(
       
       a);
       
      }
       
       bufferedInputStream.
       
       close();
       
       bufferedOutputStream.
       
       close();
       
    } 
       
       catch (
       
       FileNotFoundException 
       
       e) {
       
       // TODO Auto-generated catch block
       
       e.
       
       printStackTrace();
       
    } 
       
       catch (
       
       IOException 
       
       e) {
       
       // TODO Auto-generated catch block
       
       e.
       
       printStackTrace();
       
    }
       
       long 
       
       end
       
       =
       
       System.
       
       currentTimeMillis();
       
       System.
       
       out.
       
       println(
       
       " It always takes time to copy files :"
       
       +(
       
       end
       
       -
       
       begin)
       
       +
       
       " millisecond ");
      
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I/O Example operation _ Copy file _03

3、 Constantly read data from one file and write it to another file

       
       File 
       
       file
       
       =
       
       new 
       
       File(
       
       "d:/aa/person.java");
       
       File 
       
       toFile
       
       =
       
       new 
       
       File(
       
       "d:/aa/person2.java");
       
       long 
       
       begin
       
       =
       
       System.
       
       currentTimeMillis();
       
       try {
       
       // Create a buffered character input stream ( First create a character input stream )
       
       FileReader 
       
       fileReader 
       
       =
       
       new 
       
       FileReader(
       
       file);
       
       BufferedReader 
       
       bufferedReader
       
       =
       
       new 
       
       BufferedReader(
       
       fileReader);
       
       // Create a buffered character output stream ( First create a character output stream )
       
       FileWriter 
       
       fileWriter
       
       =
       
       new 
       
       FileWriter(
       
       toFile);
       
       BufferedWriter 
       
       bufferedWriter
       
       =
       
       new 
       
       BufferedWriter(
       
       fileWriter);
       
       // The loop reads from one place   Write to another file 
       
       String 
       
       str;
       
       while((
       
       str
       
       =
       
       bufferedReader.
       
       readLine())
       
       !=
       
       null)
       
       bufferedWriter.
       
       write(
       
       str);
       
       bufferedReader.
       
       close();
       
       bufferedWriter.
       
       close();
       
        } 
       
       catch (
       
       FileNotFoundException 
       
       e) {
       
       // TODO Auto-generated catch block
       
       e.
       
       printStackTrace();
       
        } 
       
       catch (
       
       IOException 
       
       e) {
       
       // TODO Auto-generated catch block
       
       e.
       
       printStackTrace();
       
        }
       
       long 
       
       end
       
       =
       
       System.
       
       currentTimeMillis();
       
       System.
       
       out.
       
       println(
       
       " It always takes time to copy files using a buffered character stream :"
       
       +(
       
       end
       
       -
       
       begin)
       
       +
       
       " millisecond ");
      
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