Byte stream and character stream commonly used in Java

• IO stream (input stream, output stream)
• Byte stream, character stream

1. byte stream:

• • InputStream, OutputStream
  • InputStream abstracts the way the application reads data;
  • OutputStream abstracts the way the application writes out data;

　2.eof=end read-1 reading to the end

3. Basic method of input stream:

• • int B=in.read (); reads a byte unsigned fill to int low eight bits;-1 is EOF;
  • In.read (byte[] buf)
  • In.read (byte[] buf,int start,int size)

4. Basic method of output stream:

• • Out.write (int b) writes out a byte to stream, B's low 8 bits;
  • Out.write (byte[] buf) writes the BUF byte array to the stream;
  • Out.write (byte[] buf,int start,int size)

5.FileInputStream---> Specifically read the data on the file, the following see the simplest file read:

 PackageCom.wxd.test2;ImportJava.io.FileInputStream;Importjava.io.IOException; Public classIoutil {/*** Read the contents of the specified file, output to the console according to 16 input * and 10 bytes per output *@paramFileName*/     Public Static  voidPrinthex (String fileName)throwsIOException {//read the file as a byte streamFileInputStream in =NewFileInputStream (fileName); intb; intI=1;  while((B=in.read ())!=-1){            if(b<=0xf){                //number of units front complement 0System.out.print (0); } System.out.print (integer.tohexstring (b)+" "); if(i++%10==0) {System.out.println ();    }} in.close (); }}

6.FileOutputStream implements the method of writing byte data to a file:

 PackageCom.wxd.test2;ImportJava.io.FileOutputStream;Importjava.io.IOException; Public classFileOutDemo1 { Public Static voidMain (string[] args)throwsioexception{//If the file does not exist, it is created directly if it exists after deletion.FileOutputStream out=NewFileOutputStream ("Demo/out.dat"); Out.write (' A ');//write down eight bits of ' A ' characterOut.write (' B ');//write down eight bits of ' B ' character        inta=10;//Write only writes low eight bits write an int need to write four times each time 8 bitsOut.write (a>>>24); Out.write (A>>>16); Out.write (A>>>8);        Out.write (a); byte[] zg= "China". GetBytes ("UTF-8");        Out.write (ZG);        Out.close (); Ioutil.printhex ("Demo/out.dat"); }}

7.dataoutputstream/datainputstream to the "flow" function, it can be more convenient to read Int,long, characters and other types of data:

• • Writeint ()/writedouble ()/writeutf ()

 PackageCom.wxd.test2;ImportJava.io.DataOutputStream;ImportJava.io.FileOutputStream;Importjava.io.IOException; Public classDosdemo { Public Static voidMain (string[] args)throwsIOException {String file= "Demo/dos.dat"; DataOutputStream dos=NewDataOutputStream (Newfileoutputstream (file)); Dos.writeint (10); Dos.writeint (-10); Dos.writelong (10l); Dos.writedouble (10.5); //write with UTF-8 codeDOS.WRITEUTF ("China")); //write with UTF-16BE codeDos.writechars ("China"));    Dos.close (); }}

 PackageCom.wxd.test2;ImportJava.io.DataInputStream;ImportJava.io.FileInputStream;Importjava.io.IOException; Public classDisdemo { Public Static voidMain (string[] args)throwsIOException {String file= "Demo/dos.dat"; DataInputStream Dis=NewDataInputStream (Newfileinputstream (file)); intI=dis.readint ();//actually made 4 reads, because int is 32 bitsSystem.out.println (i); I=Dis.readint ();        System.out.println (i); LongL=dis.readlong ();//actually did 8 read, should be a long is 64 bitSystem.out.println (L); DoubleD=dis.readdouble ();        System.out.println (d); String s=Dis.readutf ();        System.out.println (s);    Dis.close (); }}

　　7.bufferedinputstream&bufferedoutputstrean These two streams provide the IO with a buffer, which is usually buffered when the file is opened for write or read operations, which improves IO performance

Putting data into a file from an application is equivalent to pouring a jar of water into another cylinder:

• • FileOutputStream--->write () method is equivalent to a drop of water transfer to the past
  • DataOutputStream--->writexxx () method will be convenient, the equivalent of a scoop of water transfer past
  • Bufferedoutputstream--->write () method is equivalent to a scoop of a ladle first into the bucket, and then poured from the barrel into the cylinder

 /*** * Make a copy of the file, using buffered byte stream *@paramSrcfile *@paramDestFile *@throwsIOException*/     Public Static voidCopyfilebybuffer (File srcfile,file destfile)throwsioexception{if(!srcfile.exists ()) {            Throw NewIllegalArgumentException ("File:" +srcfile+ "does not exist"); }        if(!Srcfile.isfile ()) {            Throw NewIllegalArgumentException (srcfile+ "is not a file! "); } Bufferedinputstream bis=NewBufferedinputstream (NewFileInputStream (srcfile)); Bufferedoutputstream Bos=NewBufferedoutputstream (NewFileOutputStream (destfile)); intC;  while((C=bis.read ())!=-1) {bos.write (c); Bos.flush ();//flushes the buffer, otherwise it cannot be written to;} bis.close ();    Bos.close (); }

• Character Stream
  

1. Coding issues

2. Understanding text and text files

3.Java of text (char) is a 16-bit unsigned integer that is a Unicode encoding (double-byte encoding) of a character file that is a byte of byte byte ... The data series

A text file is a sequence of text (char) that is serialized as a storage of byte in accordance with an encoding scheme (UTF-8,UTF-16BE,GBK)

4. Character Stream (Reader Writer):---> operation is a text file

Processing of characters, one character at a time

The bottom of the character is still the basic byte sequence

Basic implementation of character stream

InputStreamReader completes a byte stream parsing to a char stream, parsed by encoding

OutputStreamWriter provides a char stream to a byte stream, which is processed by encoding

 PackageCom.wxd.test2;ImportJava.io.*; Public classIsrandoswdemo { Public Static voidMain (string[] args)throwsioexception{//InputStreamReader is called Bridge flowFileInputStream in=NewFileInputStream ("Demo\\test.txt");//The encoding of the default item, the encoding of the file itself to be written when the operationInputStreamReader isr=NewInputStreamReader (In, "Utf-8"); FileOutputStream out=NewFileOutputStream ("Demo\\test2.txt"); OutputStreamWriter OSW=NewOutputStreamWriter (out, "Utf-8");//int C;//While ((C=isr.read ())!=-1) {//System.out.print ((char) c);//        }        Char[] buffer=New Char[8*1024]; intC; //Bulk Read, put in buffer this character array, starting from the No. 0 position, put up buffe.length//returns the number of characters that are read         while((C=isr.read (buffer,0,buffer.length))!=-1) {String s=NewString (buffer,0, c);            System.out.println (s); Osw.write (Buffer,0, c);        Osw.flush ();        } isr.close ();    Osw.close (); }}

5.filereader/filewriter (This way bu)

 PackageCom.wxd.test2;ImportJava.io.FileReader;ImportJava.io.FileWriter;Importjava.io.IOException; Public classFrandfwdemo { Public Static voidMain (string[] args)throwsioexception{FileReader FR=NewFileReader ("Demo\\test.txt"); FileWriter FW=NewFileWriter ("Demo\\text2.txt",true);//set to True to append later        Char[] buffer=New Char[2056]; intC;  while((C=fr.read (buffer,0,buffer.length))!=-1) {fw.write (buffer,0, c);        Fw.flush ();        } fr.close ();    Fw.close (); }}

6. Filter for character stream

BufferedReader----->readline read one line at a time

Bufferedwriter/printwriter----> Write a line

 PackageCom.wxd.test2;ImportJava.io.*; Public classBrandbworpwdemo { Public Static voidMain (string[] args)throwsIOException {//Read and write to a fileBufferedReader br =NewBufferedReader (NewInputStreamReader (NewFileInputStream ("Demo\\test.txt"))); /*bufferedwriter bw=new BufferedWriter (New OutputStreamWriter (New FileOutputStream ("Demo\\test3.txt"));*/PrintWriter PW=NewPrintWriter ("Demo\\test3.txt");        String Line;  while(line = Br.readline ())! =NULL) {System.out.println (line);//reads one line at a time and does not recognize line breaks            /*Bw.write (line);            Write the line-break operation separately Bw.newline (); Bw.flush ();*/pw.println (line);        Pw.flush (); } br.close ();//bw.close ();Pw.close (); }}

Byte stream and character stream commonly used in Java