Java file stream: Byte stream (FileInputStream, FileOutputStream) and character stream (FileReader, FileWriter).

The input and output of Java is based on 4 abstract classes: InputStream, OutputStream, Reader, Writer. Inputsream and OutputStream are designed as byte-stream classes, while reader and writer are designed as character stream classes. In general, you should use a character stream class when working with characters or strings, and you should use a byte stream class when working with bytes or binary objects.

Generally in the operation of the file stream, whether it is a byte stream or a character stream, can be done in the following manner.

1. Use the file class to find a document

2. Instantiate a byte stream or a stream of characters through the file class

3. Byte (character) read and write operation

4. Close file stream

Here are 2 examples of writing a string to a file and reading it.

By byte-throttling mode:

1  Packagezdxtest;2 ImportJava.io.*;3  Public classTestFile1 {4 5      Public Static voidMain (string[] args) {6         //TODO auto-generated Method Stub7         //byte stream input output, write content to a file and read8File f =NewFile ("D:\\1.txt");9FileOutputStream fos =NULL;TenFileInputStream foi =NULL; OneString sin = "Today is the last day of July"; A         //Create the file, if the file exists under the directory, first delete and then create -         if(F.exists ()) { - F.delete (); the             Try { - f.createnewfile (); -}Catch(IOException e) { -                 //TODO auto-generated Catch block + e.printstacktrace (); -             }     +         } A         Else{ at             Try { - f.createnewfile (); -}Catch(IOException e) { -                 //TODO auto-generated Catch block - e.printstacktrace (); -             } in         } -         //instantiate byte stream subclass: FileOutputStream to         Try { +FOS =NewFileOutputStream (f); -}Catch(FileNotFoundException e) { the             //TODO auto-generated Catch block * e.printstacktrace (); $         }Panax Notoginseng         //writes a file in bytes and closes the stream -         byte[] B =sin.getbytes (); the         Try { + Fos.write (b); A fos.close (); the}Catch(IOException e) { +             //TODO auto-generated Catch block - e.printstacktrace (); $         } $         //instantiate byte stream subclass: FileInputStream -         Try { -FOI =NewFileInputStream (f); the}Catch(FileNotFoundException e) { -             //TODO auto-generated Catch blockWuyi e.printstacktrace (); the         } -         //reads the file in bytes and closes the stream Wu         byte[] C =New byte[1000]; -         intL=0; About         Try {         $             /*L = foi.read (); - While (l!=-1) { - System.out.println (string.valueof (L)); - L=foi.read (); A             }*/ +L =Foi.read (c); the foi.close (); -}Catch(IOException e) { $             //TODO auto-generated Catch block the e.printstacktrace (); the         } theString o =NewString (c); theSystem.out.println (o);//Print File Contents -System.out.println (l);//number of bytes to print read in  the     } the  About}

Post-run output:

Today is the last day of July

27

Why is it 27 bytes, because my default encoding for Eclipse is UTF-8, in UTF-8 encoding, a Chinese character is three bytes, a total of 9 Chinese characters, so it is 27 bytes.

Then look at the way the character stream is implemented:

1  Packagezdxtest;2 ImportJava.io.*;3 4  Public classFileTest2 {5 6      Public Static voidMain (string[] args) {7         //TODO auto-generated Method Stub8File f =NewFile ("D:\\2.txt");9FileReader FR =NULL;TenFileWriter FW =NULL; OneString s = "Tomorrow is the first day of August"; A         //Create the file, if the file exists under the directory, first delete and then create -         if(F.exists ()) -         { the F.delete (); -             Try { - f.createnewfile (); -}Catch(IOException e) { +                 //TODO auto-generated Catch block - e.printstacktrace (); +             } A         } at         Else{ -             Try { - f.createnewfile (); -}Catch(IOException e) { -                 //TODO auto-generated Catch block - e.printstacktrace (); in             } -         } to         //instantiate character Stream subclass: FileWriter, writes the file as characters and closes the stream +         Try { -FW =NewFileWriter (f); the Fw.write (s); * fw.close (); $}Catch(IOException e) {Panax Notoginseng             //TODO auto-generated Catch block - e.printstacktrace (); the         } +         //instantiate character Stream subclass: FileReader, reads the file as characters and closes the stream A         Char[] B =New Char[1000]; the         intL = 0; +         Try { -FR =NewFileReader (f); $L =Fr.read (b); $}Catch(IOException e) { -             //TODO auto-generated Catch block - e.printstacktrace (); the         } -System.out.println (NewString (b));//Print File ContentsWuyiSystem.out.println (l);//number of characters to print read the     } -  Wu}

Run output:

Tomorrow is the first day of August.

8

Altogether 8 kanji, one char stores a kanji, so it is 8 characters

Java file stream: Byte stream (FileInputStream, FileOutputStream) and character stream (FileReader, FileWriter).