《输入与输出 》PPT课件.ppt

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1、第八章 输入与输出n概念nJava I/O类nJava I/O操作n标准输入/输出n文件读写操作n目录管理n随机访问文件概念n数据流：一组有顺序的有起点和终点的字节集合。n以流(stream)的方式对数据进行操作数据源程序读出数据流目的程序写入数据流l I/O来源 控制台(console)打印/读入 文件(file)读/写 网络接口(TCP/UDP端口)读/写概念n读/写流的一般流程n读(Reading)1.openastream/打开读出流2.whilemoreinformation/判断3.readinformation/读4.closethestream/关闭流n写(Writing)1.

2、openastream/打开写入流2.whilemoreinformation/判断3.writeinformation/写4.closethestream/关闭流概念n两种流的定义(读取信息的基本数据单位)n字节流(byte stream):一个字节(8-bit)一个字节读/写n字符流(character stream):一个字符一个字符读/写eg “j a v a 语 言”以字节流的方式读:读8次，8个字节 以字符流的方式读:读6次，6个字符JavaI/O类n字节流的读/写操作(来自JDK1.0)n(抽象类)1.publicabstractintread()2.publicintread(

3、byteb)3.publicintread(byteb,intoffset,intlength)4.到达流的终点，无数据读出则返回-1n(抽象类)1.publicabstractvoidwrite(intb)2.publicvoidwrite(byteb)3.publicvoidwrite(byteb,intoffset,intlength)n所有的读/写函数都抛出JavaI/O类n字符流的读/写操作(来自JDK1.1)n(抽象类)1.publicintread()2.publicintread(charcbuf)3.publcabstractintread(charcbuf,intoffse

4、t,intlength)4.到达流的终点，无数据读出则返回-1n(抽象类)1.publicvoidwrite(intc)2.publicvoidwrite(charcbuf)3.publicvoidwrite(charcbuf,intoffset,intlength)n所有的读/写函数都抛出JavaI/O类nI/O流的层次关系nclass的子类nclassnclassjava.io.FileInputStreamnclassnclassjava.io.BufferedInputStreamnclassnclassnclassnclassnclassnclassnclassnJavaI/O类nI

5、/O流的层次关系nclass的子类nclassnclassjava.io.FileOutputStreamnclassnclassjava.io.BufferedOutputStreamnclassnclassnclassnclassnJavaI/O类nI/O流的层次关系nclass的子类nclassjava.io.BufferedReadernclassnclassnclass nclassnclassnclassjava.io.FileReadernclassnclassnJavaI/O类nI/O流的层次关系nclass的子类nclassjava.io.BufferedWriterncla

6、ssnclassnclassnclassjava.io.FileWriternclassnclassnclassnJavaI/O类nI/O流的分类(12个功能类)I/O类型所用到的类描述文件FileReader/FileWriterFileInputStream/FileOutputStream文件流(读/写文件)缓冲BufferedReader/BufferedWriterBufferedInputStreamBufferedOutputStream提高读/写效率打印PrintWriterPrintStream(System.out.println()提供打印内存CharArrayReade

7、r/CharArrayWriterByteArrayInputStreamByteArrayOutputStreamStringReader/StringWriterStringBufferInputStream读/写内存中字节/字符数组JavaI/O类nI/O流的分类(12个功能类)I/O类型所用到的类描述字节流和字符流的转换InputStreamReaderOutputStreamWriter将字节转为字符流输入/将字符流转为字节流输出管道pipePipedReader/PipedWriterPipedInputStream/PipedOutputStream将一个线程的输出作为另一个线程

8、的输入连接ConcatenationSequenceInputStream多个输入流连接为一个输入流对象串行化ObjectInputStreamObjectOutputStreamObjectSerializationJavaI/O类nI/O流的分类(12个功能类)I/O类型所用到的类描述基本数据转化DataInputStreamDataOutputStreamJAVA基本数据类型的读/写计数LineNumberReaderLineNumberInputStream读操作时记录行数PeekingAheadPushbackReaderPushbackInputStream可回退缓存(pushba

9、ckbuffer)过滤FilterReader/FilterWriterFilterInputStream/FilterOutputStream在读/写操作时对数据进行过滤标准输入/输出nSystem.in System.out System.err 1()2 print(参数),println(参数)classTestpublicstaticvoidmain(Stringargs)System.out.println(“HelloWorld!”);import;classTestpublicstaticvoidmain(Stringargs)throwsIOExceptionbyteb=ne

10、wbyte10;System.out.println(Receivednumber=+System.in.read(b);C:javaTestAReceivednumber=3C:【示例8-1】IOExample.JavaimportJava.io.IOException;classIOExamplepublicstaticvoidmain(Stringargs)throwsIOExceptionchara;System.out.print(Pleaseinputachar:);a=(char)System.in.read();System.out.println(Thecharis:+a);

11、程序运行结果：程序运行结果：Pleaseinputachar:(键入任意一个字符（C），回车)输出：Thenumberis:C8.3 常用的流类文件管理File类File类包含许多用于执行文件常规操作的方法。可以访问指定文件的所有属性，还可以删除，创建，更名指定的文件或目录。n类:文件和目录的路径名n路径名(pathname)nUNIX平台上绝对路径的前缀“/”，相对路径无前缀，例“/etc/inetd.conf”、“inetd.conf”nWindows平台，绝对路径名的前缀由“盘符:”组成，或共享名前缀“”，然后是主机名和共享名，相对路径名无盘符，例“c:windowsnotepad.ex

12、e”、“192.168.1.10Test.java”n构造方法npublicFile(Stringpathname)npublicFile(Stringparent,Stringchild)npublicFile(Fileparent,Stringchild)nparent通常表示一个目录，child则表示一个目录或文件文件管理File类常用方法public String getAbsolutePath()public boolean canWrite()/canRead()publicbooleanrenameTo(Filedest)public boolean delete()public

13、 boolean exists()public String getName()public String getParent()public boolean isDirectory()public boolean isFile()public String list()public String list(FilenameFilter filter)public boolean mkdir()public URL toURL()文件管理File类方法举例import;publicclassDirListpublicstaticvoidmain(Stringargs)Filepath=newF

14、ile(.);Stringlist=path.list();for(inti=0;ilist.length;i+)System.out.println(listi);import;import;publicclassDirListpublicstaticvoidmain(Stringargs)Filepath=newFile(.);Stringlist=path.list(newDirFilter(args0);for(inti=0;ilist.length;i+)System.out.println(listi);classDirFilterimplementsFilenameFilter

15、Stringkey;DirFilter(Stringkey)this.key=key;publicbooleanaccept(Filedir,Stringname)Stringf=newFile(name).getName();returnf.indexOf(key)!=-1;接口publicbooleanaccept(Filedir,Stringname);/是否指定的文件应包含在文件列表中publicStringgetName()in/获得文件或目录名文件读写操作n文件读/写流程1.打开文件流2.条件判断3.读出/写入4.关闭文件流n两种类型文件nFileInputStream/FileO

16、utputStream(字节流)nFileReader/FileWriter(字符流)1.字节流构造方法npublicFileInputStream(Stringname)throwsFileNotFoundExceptionnpublicFileInputStream(Filefile)throwsFileNotFoundExceptionnpublicFileOutputStream(Filefile)throwsFileNotFoundExceptionnpublicFileOutputStream(Filefile,booleanappend)throwsFileNotFoundExc

17、eption/是否向已存在的文件后添加npublicFileOutputStream(Stringname)throwsFileNotFoundExceptionnpublicFileOutputStream(Stringname,booleanappend)throwsFileNotFoundException文件读写操作文件读写操作2.字节流方法npublicintread()throwsIOExceptionnpublicintread(byteb)throwsIOExceptionnpublicintread(byteb,intoffset,intlen)throwsIOExcepti

18、onnpublicvoidclose()throwsIOExceptionnpublicvoidwrite(intb)throwsIOExceptionnpublicvoidwrite(byteb)throwsIOExceptionnpublicvoidwrite(byteb,intoffset,intlen)throwsIOException典型的读文件程序import;import;publicclassFileInputDemopublicstaticvoidmain(Stringargs)throwsIOExceptionFileInputStreamfile=newFileInput

19、Stream(args0);intc;while(c=file.read()!=-1)System.out.print(char)c);file.close();import;import;import;import;publicclassCopyBytesDemo1publicstaticvoidmain(Stringargs)throwsIOExceptionFileinputFile=newFile(args0);FileoutputFile=newFile(args1);FileInputStreamin=newFileInputStream(inputFile);FileOutput

20、Streamout=newFileOutputStream(outputFile);intc;while(c=in.read()!=-1)out.write(c);in.close();out.close();importjava.io.*;publicclassc8_7publicstaticvoidmain(Stringargs)charc;intc1;FilefilePath=newFile(temp);if(!filePath.exists()filePath.mkdir();Filefl=newFile(filePath,d1.txt);tryFileOutputStreamfout

21、=newFileOutputStream(fl);(请输入字符,输入结束按#:);while(c=()!=#)fout.write(c);fout.close();System.out.println(n打印从磁盘读入的数据);FileInputStreamfin=newFileInputStream(fl);while(c1=fin.read()!=-1)System.out.print(char)c1);fin.close();catch(FileNotFoundExceptione)System.err.println(e);catch(IOExceptione)System.err.p

22、rintln(e);运行结果如下运行结果如下:请输入字符，输入结束按请输入字符，输入结束按 abcd#打印从磁盘读入的数据打印从磁盘读入的数据 abcd#【示例8-2】FileOutputDemo.Javaimport;import;import;import;import;publicclassFileOutputDemopublicstaticvoidmain(Stringargs)throwsIOExceptionFilefileSource=newFile(output.txt);FilefileTarget=newFile(intput.txt);FileOutputStreamta

23、rget=newFileOutputStream(fileTarget);FileInputStreamsource=newFileInputStream(fileSource);intc;while(c=source.read()!=-1)target.write(c);target.close();source.close();文件读写操作字符流构造方法npublicFileReader(Filefile)throwsFileNotFoundExceptionnpublicFileReader(StringfileName)throwsFileNotFoundExceptionnpubli

24、cFile(Stringpathname)npublicFileWriter(Filefile)throwsIOExceptionnpublicFileWriter(Filefile,booleanappend)throwsIOExceptionnpublicFileWriter(StringfileName)throwsIOExceptionnpublicFileWriter(StringfileName,booleanappend)throwsIOExceptionimportjava.io.*;publicclassCopypublicstaticvoidmain(Stringargs)

25、throwsIOExceptionFileinputFile=newFile(“original.txt);FileoutputFile=newFile(“result.txt);FileReaderin=newFileReader(inputFile);FileWriterout=newFileWriter(outputFile);intc;while(c=in.read()!=-1)out.write(c);in.close();out.close();FileReaderin=newFileReader(“original.txt);FileWriterout=newFileWriter

26、(“result.txt);publicintread()throwsIOExceptionpublicintread(charcbuf)throwsIOExceptionpublicintread(charcbuf,intoff,intlen)throwsIOExceptionpublicvoidwrite(intb)throwsIOExceptionpublicvoidwrite(charcbuf)throwsIOExceptionpublicvoidwrite(charcbuf,intoff,intlen)throwsIOExceptionDataInputStream和DataOutp

27、utStreamn概述n类npublicDataInputStream(InputStreamin)npublicfinalbooleanreadBoolean()npublicfinalbytereadByte()npublicfinalcharreadChar()npublicfinalintreadInt()n类npublicDataOutputStream(OutputStreamout)npublicfinalvoidwriteBoolean(booleanv)npublicfinalvoidwriteByte(intv)npublicfinalvoidwriteChar(intv)

28、npublicfinalvoidwriteInt(intv)DataOutputStreamout=newDataOutputStream(newFileOutputStream(invoice1.txt);doubleprices=19.99,9.99;intunits=12,8;Stringdescs=JavaT-shirt,JavaMug;for(inti=0;iprices.length;i+)out.writeDouble(pricesi);out.writeChar(t);out.writeInt(unitsi);out.writeChar(t);out.writeChars(de

29、scsi);out.writeChar(n);out.close();19.9912JavaT-shirt9.998JavaMugDataInputStreamin=newDataInputStream(newFileInputStream(invoice1.txt);doubletotal;trywhile(true)doubleprice=in.readDouble();in.readChar();intunit=in.readInt();in.readChar();charchr;StringBufferdesc=newStringBuffer(20);while(chr=in.read

30、Char()!=n)desc.append(chr);System.out.println(Youveordered+unit+unitsof+desc+at$+price);total=total+unit*price;catch(EOFExceptione)System.out.println(ForaTOTALof:$+total);in.close();用于跟踪中间流的类PushbackInputStream构造方法：PushbackInputStream(InputStreamin)PushbackInputStream(InputStreamin,intsize)代表方法：Void

31、unread(intn)回退一个字节BufferedInputStream/BufferedOutputStreamn构造方法npublicBufferedInputStream(InputStreamin)2048bytesnpublicBufferedInputStream(InputStreamin,intsize)npublicBufferedOutputStream(OutputStreamout)512bytesnpublicBufferedOutputStream(OutputStreamout,intsize)npublicBufferedReader(Readerin)819

32、2bytesnpublicBufferedReader(Readerin,intsz)npublicBufferedWriter(Writerout)8192bytenpublicBufferedWriter(Writerout,intsz)Stringfilename=“test.txt”;FileInputStreamfis=newFileInputStream(filename);intcount=0;intc;while(c=fis.read()!=-1)if(c=A)count+;fis.close();System.out.println(count);Stringfilename

33、=“test.txt”;FileInputStreamfis=newFileInputStream(filename);BufferedInputStreambis=newBufferedInputStream(fis);intcount=0;intc;while(c=bis.read()!=-1)if(c=A)count+;fis.close();System.out.println(count);BufferedInputStream/BufferedOutputStream数据的读写随机访问文件n随机访问文件(RandomAccessFile)n类n读写操作在同一个类中完成，须在构造对象

34、时指定参数n通过移动文件指针(filepointer)在文件的指定位置进行读写操作n构造方法npublicRandomAccessFile(Stringname,Stringmode)throwsFileNotFoundExceptionnpublicRandomAccessFile(Filefile,Stringmode)throwsFileNotFoundExceptionnmode:“r”,“rw”随机访问文件n方法npublicintread()npublicintread(byteb)npublicintread(byteb,intoff,intlen)npublicfinalboo

35、leanreadBoolean()/readByte()/readChar()/readShort()/readInt()/readDouble()/readFloat()npublicfinalStringreadLine()npublicvoidwrite(intb)npublicvoidwrite(byteb)npublicvoidwrite(byteb,intoff,intlen)npublicfinalvoidwriteBoolean()/writeByte()/writeChar()/writeShort()/writeInt()/writeDouble()/writeFloat(

36、)随机访问文件n方法npublicvoidseek(longpos)throwsIOExceptionnpublicintskipBytes(intn)throwsIOExceptionnpubliclonggetFilePointer()throwsIOExceptionnpubliclonglength()throwsIOExceptionnvoidsetLength(longnewLength)import;import;import;publicclassRAFDemopublicstaticvoidmain(Stringargs)tryRandomAccessFilerf=newRa

37、ndomAccessFile(test.dat,rw);for(inti=0;i10;i+)rf.writeDouble(i*1.48);rf.close();rf=newRandomAccessFile(test.dat,rw);rf.seek(5*8);rf.writeDouble(47.0001);rf.close();rf=newRandomAccessFile(test.dat,r);for(inti=0;i10;i+)System.out.println(Value+i+:+rf.readDouble();rf.close();catch(FileNotFoundException

38、e)System.out.println(e);catch(IOExceptione)System.out.println(e);管道类在两个线程间建立数据流的通道PipedInputStream类创建输入管道PipedOutputStream类创建输出管道管道类的模型两个继承体系之间的类的对应关系Filter两个继承体系之间类的对应关系FileReader和FileWriter FileReader构造方法publicFileReader(StringfileName)throwsFileNotFoundExceptionpublicFileReader(Filefile)throwsFil

39、eNotFoundExceptionFileWriter构造方法publicFileWriter(Filefile)throwsIOExceptionpublicFileWriter(Filefile,booleanappend)throwsIOExceptionpublicFileWriter(StringfileName)throwsIOExceptionpublicFileWriter(StringfileName,booleanappend)throwsIOExceptionimportjava.io.*;publicclassCopyCharDemopublicstaticvoidm

40、ain(Stringargs)throwsIOExceptionFileinputFile=newFile(args0);FileoutputFile=newFile(args1);FileReaderin=newFileReader(inputFile);FileWriterout=newFileWriter(outputFile);intc;while(c=in.read()!=-1)out.write(c);in.close();out.close();字节流向字符流的转化InputStreamReader的构造函数publicInputStreamReader(InputStreami

41、n)publicInputStreamReader(InputStreamin,StringcharsetName)throwsUnsupportedEncodingExceptionpublicInputStreamReader(InputStreamin,Charsetcs)publicInputStreamReader(InputStreamin,CharsetDecoderdec)字节流向字符流的转化OutputStreamWriter的构造函数publicOutputStreamWriter(OutputStreamout)publicOutputStreamWriter(OutputStreamout,StringcharsetName)throwsUnsupportedEncodingExceptionpublicOutputStreamWriter(OutputStreamout,Charsetcs)publicOutputStreamWriter(OutputStreamout,CharsetEncoderenc)