JAVA I/O

1
JAVA I/O
2
OUTLINE

• I/O streams
• Byte Streams
• Character Streams
• Buffered Stream
• I/O from the Command Line
• Standard I/O
• java.io.Console
• File I/O
• File I/O
• Data Streams
• Object Streams

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I/O STREAMS

• ??????0?1???????
• ?source??input stream ????
• ????output stream ?????

source
read
program
0101
destination
write
program
0101
4
BYTE STREAMS

• ?????
• Input?output????????????(8-bits)
• Ex. System.in, FileInputStream/FileOutputStream

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Java.io.
FileInputStream
InputStream
FilterInputStream
BufferedInputStream
FileOutputStream
OutputStream
BufferedOutputStream
FilterOutputStream
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SYSTEM.IN

• ????8 bits
• Output????ASCII code(A65)

7
FILEINPUTSTREAM/FILEOUTPUTSTREAM

• FileInputStream?????bytes
• FileOutputStream ?bytes??????
• ????????????java.io.FileNotFoundException

8
FILEINPUTSTREAM/FILEOUTPUTSTREAM
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FILEINPUTSTREAM/FILEOUTPUTSTREAM
InputStream
t
e
s
t
f
o
r
b
y
t
e
s
t
r
e
a
m
read()
int c (b 98)
write(c)
t
e
s
t
f
o
r
b
OutputStream
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CHARACTER STREAMS

• ????
• ????(Unicode)??????????????????character stream,
  ????2 bytes
• Ex. FileReader/FileWriter

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Java.io.
BufferedReader
Reader
FileReader
InputStreamReader
BufferedWriter
Writer
FileWriter
OutputStreamWriter
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FILEREADER/FILEWRITER
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FILEREADER/FILEWRITER

• FileReader?character stream,????????,???FileInputS
  tream(?byte stream)????????????????

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BUFFERED STREAM

• ????
• ???????????, Buffered Stream?????????????,????????
  ?,????????????,?????????????,?????????

read
file
memory
program
0101
write
file
program
memory
0101
15
BUFFERED STREAM

• BufferedInputStream, BufferedOutputStream?byte
  stream?????
• BufferedReader, BufferedWriter??character
  stream?????

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BUFFERED STREAM
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I/O FROM THE COMMAND LINE

• ???????,???????

read
program
0101
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STANDARD I/O

• Standard input System.in
• Standard output System.out
• Standard error System.err

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STANDARD I/O

• ??????BufferedReader bf new BufferedReader(new
  InputStreamReader(System.in))
• new InputStreamReader(System.in)??System.in???????
  ?????????
• ??buffered stream?????buffer?,?????????????????
  bf.readLine(),????

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STANDARD I/O
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JAVA.IO.CONSOLE

• JAVA JDK6???
• ??System?console()??,??????Console??(Console
  ???????????,?? Windows ????????),?????????????????
  ?????
• ?standard I/O????

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JAVA.IO.CONSOLE
????????????,????????????
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FILE I/O

• ?????????????????

read
File
program
0101
24
FILE I/O

• ????

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DATAINPUTSTREAM/DATAOUTPUTSTREAM

• DataInputStream reads bytes from the stream and
  converts them into appropriate primitive type
  values or strings.
• DataOutputStream converts primitive type values
  or strings into bytes and outputs the bytes to
  the stream.

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DATAINPUTSTREAM/DATAOUTPUTSTREAM
DataInputStream
DataOutputStream
readBoolean() readByte() readChar() readFloat() re
adInt()
writeBoolean() writeByte() writeChar() writeFloat(
) writeInt()
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DATAINPUTSTREAM/DATAOUTPUTSTREAM


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OBJECTSTREAM

• ????
• ObjectOutputStream????????????,????????ObjectInput
  Stream???????????

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OBJECTSTREAM