Usage principles for various classes of IO streams in Java

Reference: http://blog.csdn.net/ilibaba/article/details/3955799

The general use principle of Java IO (many eye disorder, in fact, each class has a special role):

Here are the details:Introduction to Java IO input and output stream class (with image)

First, according to the data source (the whereabouts, that is,Granules) Categories: 1, Documents:

FileInputStream, FileOutputStream, (Byte stream)

FileReader, FileWriter (character stream)

2, byte array byte[]:

Bytearrayinputstream, Bytearrayoutputstream (Byte stream)

3, character array char[]:

CharArrayReader, Chararraywriter (character stream)

4. Strings string:

Stringbufferinputstream,stringbufferouputstream (Byte stream)
StringReader, StringWriter (character stream)

5. Network Data Flow:

InputStream, OutputStream, (Byte stream)
Reader, Writer (character stream)

Second, according to whether to format the output points:1. To format the output：

PrintStream (byte stream only), printwriter(Byte stream and character stream)

Three, according to whether to buffer points: (generally recommended use, can improve efficiency) 1, to buffer:

Bufferedinputstream, Bufferedoutputstream, (Byte stream)
BufferedReader, BufferedWriter (character stream)

Four, according to the data format: (the most fundamental, in addition to text files using character stream, all other byte stream priority) 1, binary format (as long as it is not determined to be plain text):

InputStream, OutputStream and all subclasses with Stream end

2, plain text format (including pure English and Chinese characters or other encoding method):

Reader, writer , and all subclasses of writer with reader

V. Special needs: 1. Conversion class from Stream to Reader,writer:

InputStreamReader, OutputStreamWriter

2. Object input and output:

ObjectInputStream, ObjectOutputStream

3. Inter-process communication:

Pipeinputstream, Pipeoutputstream, (Byte stream)

Pipereader, Pipewriter (character stream)

4. Merge input:

Sequenceinputstream

5, more special needs:

Pushbackinputstream, Pushbackreader, Linenumberinputstream, LineNumberReader

Steps to use the principle *************************************
The general guidelines for deciding which class to use and how to construct it are as follows (regardless of special needs):

First, consider what the most primitive data format is:

principle Four (binary or plain text, directly deciding whether to use a byte stream or a character stream )

Second, whether the stream needs to be converted:

principle Six 1th ( byte-to-character, character-to-byte )

Third, what is the source of the data (whereabouts):

principle One ( particle: basic unit, is file, byte array/character array, String,object)

Four, whether to buffer:

principle Three (Special note: It must be noted that ReadLine () has a definition , what is more than read, write a more special input or output method, usually more recommended to use, can improve efficiency

the normal inputstream/outputstream or reader/writer do not define the ReadLine () method , That is, you cannot output a string directly from the console ,

The buffered buffer stream has a defined readline (), but cannot be wrapped automatically, requires newline () manual generation , and PrintStream and PrintWriter have prin TLN () method )

Five, whether to format the output: (In fact, it is directly output)

principle Two (Printstream,printwriter)

A few examples **********************************

Java simple code for copying files: 1. Use byte stream (all can come out)

1  Packageiotest;2 3 ImportJava.io.*;4 ImportJava.util.*;5 /**6 * A simple example of Java copying Files7  * */8  Public classCopywithoutbuffer {9      Public Static voidMain (string[] args) {Ten         LongStart =System.currenttimemillis (); OneSYSTEM.OUT.PRINTLN ("Begin copy ....")); A         Try { -FileInputStream FIS =NewFileInputStream ("E:\\12.mp4"); -FileOutputStream fos =NewFileOutputStream ("E:\\123.mp4"); the             //buffered streams are used here to improve efficiency -Bufferedinputstream bis =NewBufferedinputstream (FIS); -Bufferedoutputstream BOS =NewBufferedoutputstream (FOS); -             Try { +                 byte[] buf =New byte[1024]; -                 ////using buffer +                 intRead =Bis.read (BUF); A                  while(Read!=-1){ atBos.write (Buf,0,read);//because BUF may be dissatisfied at the end of the reading, read will prevail. -Read =Bis.read (BUF); -                 } -  - //                //do not use a buff, do not use a byte array, much less efficient, time-consuming - //int read = Bis.read ();//read one byte at a time in //While (read!=-1) { - //Bos.write (read); to //read = Bis.read (); + //                } - bos.close (); the fos.close (); * bis.close (); $ fis.close ();Panax Notoginseng}Catch(IOException e) { - e.printstacktrace (); the             } +              A}Catch(FileNotFoundException e) { the e.printstacktrace (); +         } -          $         LongEnd =System.currenttimemillis (); $System.out.println ("Copy complete,use Times:" + (End-start) + "MS"); -     } -  the}

View Code2. Use a character stream (can only handle plain text files (faster than byte stream processing), video audio will be problematic):

1  Packageiotest;2 3 ImportJava.io.*;4 5  Public classIoreadertest {6      Public Static voidMain (string[] args) {7System.out.println ("Start");8         LongStart =System.currenttimemillis ();9         Try {TenFileReader FR =NewFileReader ("E:\\123.txt"); OneFileWriter FW =NewFileWriter ("E:\\123456.txt"); A             /* - bufferedreader br = new BufferedReader (FR); - String ABC = br.readline ();//bufferedreader defines the ReadLine () method the //If you want to wrap, you need to generate the Br.newline () manually. - SYSTEM.OUT.PRINTLN (ABC); -             */ -             intRead =Fr.read (); +              while(Read!=-1){ - Fw.write (read); +Read =Fr.read (); A             } at fw.close (); - fr.close (); -             LongEnd =System.currenttimemillis (); -SYSTEM.OUT.PRINTLN ("Time Consuming:" + (End-start) + "MS"); -}Catch(FileNotFoundException e) { - e.printstacktrace (); in}Catch(IOException e) { - e.printstacktrace (); to         } +  -     } the  *}

View Code

Usage principles for various classes of IO streams in Java