1-1??/??I/O

1
1-1??/??I/O

• ????????????????????????input Stream,???????????Ou
  tput Stream??JAVA???????,??????(In)???????(out)???
  ????(err)?System????????(In?out?err)??????????????
  ?public static,???????System?????????????????????,
  ??System.out.println()????????????????????Scanner?
  ??
• ??I/O??,?????I/O???System.in??????,System.out?Syst
  em.err???????IOException???????,??????catch???????
  ??throws????????I/O?????????????????????????????,?
  ?????I/O?????try..catch????

2

• ??FileReader_test.java
• ????text.txt???????
• ?????java.io.???
• ???????????FileReader????????input?
• ??????????trycatchfinally???
• ?????test.txt??????
• ???input.read()???????byte???,???code,-1???????
• ?FileReader??????????????,???????try..catch???????
  java.io.FileNotFoundException?IOException????,???F
  ileNotFoundException??IOException???
• ??????input.close()???????

3
??FileWriter_test.java

• ????????good.txt??
• ???main()?????IOException???
• ?????FileWriter??output???????good.txt,??????true,
  ??good.txt??????,?????????????,???????,??????,????
  ???????
• ?????output???????write()?????????
• ????????,?????????close()???

4

• ??IO.java
• ?????java.util.Random???
• ?????java.io.???
• ????????????IO???
• ????main()??,????throws??IOException?
• ???????MAX?9?
• ?????????Random()?
• ?????FileWriter?????fw,FileWriter?????????,???????
  ???????PrintWriter????print()?println()???
• ????????????????BufferedWriter,??????????
• ????????????for??,???????????test.txt??

5
1-1-1??

• ???????,?????????????I/O?????????????????????????,
  ???????????input stream???????????????,??????????o
  utput stream??????????,???????????????????????????
  ?

6
1-1-2????????

• ??????????????????,???????????????????????ASCII?,?
  ???????????ASCII?????????0?1??????????????????????
  ,??????,??????????????????????????????,???????????
  ?
• ???????text.txt,??????????????????????????????????
  ,?????????

7

• ???????????????????????binary.dat?

8

• ??????????????,???????????,???????????????????????
  ????????????????????,??????????????,??????????????
  ????????????????????,????????????
• ??????????????????Java?????,??Java????????????????

9
1-2???

• Java??????????????????????????????Java?,??????????
  ????????Java?,??????????
• ??????/???????,?????Object???
• FileWriter?????????,??????????????PrintWriter????p
  rint()?println()??????????BufferedWriter,?????????
  ?
• Reader???????????,?????????????Writer????????????

10

• ??java.io.Reader?????????lock???????Object,?????pr
  otected?,???????????????read()????????Close()?????
  ???mark()???????????markSupported()?????????mark()
  ???ready()???????????????reset()??????????

11

• ??java.io.Writer?????????lock???????Object,?????pr
  otected?,???????????????append()????????????Writer
  ????flush()??????Writer???close()??????????Write()
  ????????

12
1-2-1????

• PrintWriter??????????????PrintWriter??????print()?
  ??println()??,??????????????????
• ????FileOutputStream()??????output.txt??????output
  Stream?PrintWriter?????????try..catch???,?????????
  ??trycatch???????????????,???????????????????outp
  ut.txt?????,output.txt???????????FileOutput?????,?
  ????PrintWriter()??????????????????output.txt???Pr
  intWriter?????

13

• ?????????,FileNotFoundException???????,????????cat
  ch??????,?FileOutputStream???????FileNotFoundExcep
  tion????FileNotFoundException?IOException?????,???
  ???IOException????catch?????
• ?????????????

14

• ??????????????,????????????????????close()??,outpu
  tStream.close()??????/?????????close()????????????
  ,????????????????????????????,?????,??????????????
  ??,???????????,?????????????????????????flush()???
  ????????????
• ??try???????,???????PrintWriter????????try????
  ,??????????????,?????????,???outputStream???

15

• ??TextFileOutput.java
• ??????PrintWriter?????outputStream??try..catch????
  ?
• ????FileOutputStream()???????????????,??????try???
  ?
• ??????catch??,?????output.txt??,?????FileNotFoundE
  xception??,????????????
• ?????????????????output.txt????
• ?????????????outputStream.close()???
• ??????????
• ?????output.txt????

16
1-2-2????

• BufferReader??????????????BufferedReader???PrintWr
  iter????,???????????????,??????FileReader?????????
  BufferedReader??????
• ?????????????
• ??????????????,?????????char?????
• char next(char)(input.read())

17

• ??TextFileInput.java
• ?????java.io.BufferedReader??,????????java.io????
• ?????????FileReader()?????,???????test.txt???Buffe
  redReader()?????????????,?????????
• ???inputStream.readLine()???????
• ????inputStream.close()????????
• ??????????try..catch??,???????????????????????????
  ?,?????????????,?????

18

• ????????test.txt?
• ??????????

19
1-2-3?????????

• ?????BufferedReader???,?????readline()???read()???
  ????????readline()????????,????null??????read()???
  ?????,????-1?
• ??TextEOF.java
• ??????????BufferedReader()??,??first.txt??????
• ???????????PrintWriter()??,??????second.txt???
• ??????lineContent???????????????
• ??????????while??,???????,???????outStream,??????l
  ineContent???null?
• ????????????
• ????????????

20

• ??????first.txt??????
• ??????second.txt??????

21
1-2-4Systme.in?System.out?System.err

• System.in?System.out?System.err?????Java??????????
  ???????System.out?System.in?System.err???????????J
  ava??????????????????????,??????System???????setIn
  ()?setOut()?setErr()???????????errStream?????,????
  ?System.err????errStream?????????,??????System.set
  Err(errStream)?
• ?????????error???
• System.err.println(System.err)

22

• ??Redirection.java
• ?????PrintStream??????,?????FileOutputStream??,???
  ?error.txt???
• ??????System???????setErr(),???????error???errorSt
  ream???
• ????errorStream.close()?????errorStream?

23
1-2-5????

• File???????????????????????File???????????????????
  ,???????????????Windows???c\good\test.dat,?Java??
  ??????c\\good\\test.dat?
• new File(c\\good\\test.dat)????c\\good\\test.d
  at????

24
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25

• ??FileClass.java
• ??????????????????keyboard?
• ?????null?line???
• ????keyboard.readLine()??????????
• ????keyboard.readLine()?????????????
• ?????????File???
• ???????exists()??????????,?????,??????????????
• ?????????????????????

26
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27
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28

• ???????????good.txt????,??good.txt????,?????????
  ????????????????????????

29
1-3?????/??

• ???????????????????????????????????int???????,??0?
  1??????????,??????????,???????,??????????????
• Java??????????Java????????,???????????????????????
  ????????ObjectInputStream?ObjectOutpustStream?????
  ?????????????????????????????,???????????
• ???????byte?I/O???InputStream?????byte???????????O
  utputStream?????????????InputStream/OutputStream??
  ?Reader/Writer?????????,?????????????byte??/??,???
  ?????/??????????????

30

• ??BinaryOutput.java
• ?????ObjectOutputStrem??,?FileOutputStream??????
• ???????outputSream.writeInt(i),??????0?257?outputS
  ream????????????????

31

• ??????Binary.dat??????byte?8?bits???????,???????,?
  0?258?

32

• ??DataStreamTest.java
• ?????DataOutputStream??,???FileOutputStream???????
  ,??????tmp.dat???
• ????UTF????????Mary???outputStream????
• ????Double??????????55.5???outputStream????
• ????outputStream?????close()?
• ???????????DataInputStream??,?FileInputStream?????
  ?
• ??????inputStream?????,??readUTF()???
• ????????
• ??tmp.dat???????

33

• ??BufferedDataStreamTest.java
• ????????BufferedOutputStream?BufferedInputStream??
  ??BufferedInputStream?BufferedOutputStream????????
  ???,?????????????????????????BufferedReader?Buffer
  edWriter?????????BufferedInputStream?BufferedOutpu
  tStream????????byte????

34
1-3-1????????

• ObjectOutputStream?????????????ObjectOutputStream?
  ????????????????????????????????????I/O?????????IO
  Exception???
• ??????Binary.dat????????,????????
• ??????????????????ObjectOutputStream?????,????????
  ????FileOutputStream????FileNotFoundException??,??
  ??IOException??????IOException?????????????

35
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36
1-3-2???????????

• ObjectIntputStream?????????????ObjectIntputStream?
  ????????????????????????????????????I/O?????????IO
  Exception???
• ??????????????????ObjectInputStream?????,?????????
  ???FileInputStream????FileNotFoundException??,????
  IOException??????IOException?????????????

37

• ??BinaryInput.java
• ?????????ObjectInputStream??????,???FileInputStrea
  m????????
• ?????????????????
• ??????????inputStream?

38
1-3-3??????????

• ??ObjectInputStream?????????????,????EOFException?
  ??
• ??BinaryEof.java
• ?????????????try..catch?????????????while??,????Bi
  nary.dat???????,?????????,??,????EOFException??,??
  ?????catch????,?????????????
• ????????????inputStream.close()?

39
1-3-4???????/??

• ?????????????/?????,???????????Serializable???????
  ObjectOutputStream???writeObject()????????????????
  ?????writeObject()??????????????,??????readObject(
  )?????????,???????????????????readObject()??????Ob
  ject?????
• implements??Serializable???????serializable???????
  ????????????????wirteObject()?readObject()????????
  Serializable??,?????????ObjectOutputStream??????

40

• ??MyClass.java
• ?????java.io.Serializable?????
• ????MyClass??,????Serializable??,?????????ObjectOu
  tputStream??????

41

• ??ObjectIO.java
• ????????????????ObjectOutputStream?
• ????????oneObject???
• ????????anotherObject???
• ??????outputStream???????writeObject()??,?oneObjec
  t??????????
• ???????????????????ObjectInputStream?
• ??????????inputStream???readObject()??,?????????My
  Class???????readObject()??????Object?????
• ????inputStream?????readObject()??,?????????MyClas
  s???????readObject()??????Object???????one?two???

42
1-3-5???????????

• ????????????,?????????implements???serializable,??
  ???????writeObject()??????????readObject()???readO
  bject()??????Object?????,??????????????????

43

• ??ArrayIO.java
• MyClass??????????,????serializable???
• ?????MyClass?????a???????????????????
• ????????????ObjectOutputStream???????
• ?????a?????writeObject()?????outputStream??????
• ?????????MyClass??????b?
• ?????????????inputStream?
• ??????inputStream??????????,??????MyClass?????,???
  ????b?????
• ????????????????b??????

44
1-3-6???????

• ?????????????????,??????RandomAccessFile?????File
  pointer????????????????,??????seek()?????????File
  pointer???????
• java.io.RandomAccessFile?????????

45

• ??TestRandomAccess.java
• ?????????????????RandomAccessFile???ioStream?
• ????1???ioStream????????
• ??????ioStream.length()???????????
• ??????ioStream.getFilePointer()???????????????
• ??????ioStream.seek(1)????????????????1????
• ???????writeByte(9)???9??????1????
• ???????????????????
• ???????????????55.55??ioStream???
• ????ioStream.length()???ioStream??????
• ???????????????????????,?????????????????

46

• ?????????????????8?bytes???,????????1?byte???,???1
  1?bytes?