第4天properties、序列化流commonsio與反

17IOPropertiescommons-Properties1、Hashtable的子類(lèi)，mapload(InputStream)把指定流所對(duì)應(yīng)的文件中的數(shù)據(jù)出來(lái)，保存到Propertie集合，， commonts *Properties集合，它是唯一一個(gè)能與IO*需求：向PropertiespublicObjectsetProperty(StringkeyStringvalue)HashtableputpublicSet<String>stringPropertyNames()publicStringgetProperty(Stringkey)publicclassPropertiesDemo01publicstaticvoidmain(String[]args)Propertiesprop=new//prop.put(key,value); "," ", ", Set<String>keys=for(Stringkey:keys)//Stringvalue=prop.getProperty(key);System.out.println(key+"=="+value);}}}需求：使用Properties集合，完成把集合內(nèi)容到IO流所對(duì)應(yīng)文件中的操作1Properties publicpublicclassPropertiesDemo02publicstaticvoidmain(String[]args)throwsIOException//1，創(chuàng)建PropertiesPropertiesprop=new "," ", ", FileWriterout=new prop.store(out,"save}}perties中取出數(shù)據(jù)，保存到集合中3,把流所對(duì)應(yīng)文件中的數(shù)據(jù)到集合 把指定流所對(duì)應(yīng)的文件中的數(shù)據(jù)，出來(lái)，保存到Propertie集合publicclasspublicclassPropertiesDemo03publicstaticvoidmain(String[]args)throwsIOExceptionPropertiesprop=newFileInputStreamin=new//FileReaderin=new }}用于從流中對(duì)象的操作流ObjectInputStream 稱為反序列化流用于向流中寫(xiě)入對(duì)象的操作流 稱為序列化ObjectOutputStream將Java對(duì)象的基本數(shù)據(jù)類(lèi)型和圖形寫(xiě)入OutputStream?？梢允褂肙bjectInputStream（重構(gòu)）對(duì)象。通過(guò)在流中使用文件可以實(shí)現(xiàn)對(duì)象的持久。注意：只能將支持java.io.Serializable接口的對(duì)象寫(xiě)入流中publicpublicclassObjectStreamDemo ClassNotFoundException*將一個(gè)對(duì) publicpublicimplementsSerializableprivateStringprivateint}()(Stringname,intage)=this.age=}publicStringgetName()return}publicvoidsetName(Stringname)=}publicintgetAge()return}publicvoidsetAge(intage)this.age=}publicStringtoString()return [name="+name+",age="+age+}}類(lèi)}publicstaticvoidwriteObj()throwsIOException FileOutputStreamfos=newObjectOutputStreamoos=new }}ObjectInputStream對(duì)以前使用ObjectOutputStream寫(xiě)入的基本數(shù)據(jù)和對(duì)象進(jìn)行反序列化。支持java.io.Serializable接口的對(duì)象才能從流。publicpublicclassObjectStreamDemo ClassNotFoundException}publicstaticvoidreadObj()throwsIOException,ClassNotFoundException FileInputStreamfis=new ObjectInputStreamois=newobj=}}當(dāng)一個(gè)對(duì)象要能被序列化，這個(gè)對(duì)象所屬的類(lèi)必須實(shí)現(xiàn)Serializable化也會(huì)發(fā)生異常InvalidClasception。發(fā)生這個(gè)異常的原因如下：Serializable標(biāo)記接口。該接口給需要序列化的類(lèi)，提供了一個(gè)序列版本號(hào)。serialVersionUID.該public implementsSerializable privatestaticfinallongserialVersionUID=privateStringname;privateintage; (){} (Stringname,intage)=name;this.age=age;}publicStringgetName()return}publicvoidsetName(Stringname)=}publicintgetAge()return}publicvoidsetAge(intage)this.age=}publicStringtoString()return [name="+name+",age="+age+}}transienttransient修飾了，序列化時(shí)這個(gè)屬性就不會(huì)琲序列化了。public*public*implementsSerializableprivatestaticfinallongserialVersionUID=privatestaticStringprivatetransient/*瞬態(tài)*int ()} (Stringname,intage)=name;this.age=age;}publicStringgetName()return}publicvoidsetName(Stringname)=}publicintgetAge()return}publicvoidsetAge(intage)this.age=}publicStringtoString()return[name="+name+",age="+age+}}字節(jié)打印流字符打印流voidprint(Stringstr):voidprintln(Stringstr):需求：把指定的數(shù)據(jù)，寫(xiě)入到printFile.txt**1*2*3publicclassPrintWriterDemopublicstaticvoidmain(String[]args)throwsIOException//PrintWriterout=newPrintWriter(newFileWriter("printFile.txt"));PrintWriterout=newPrintWriter("printFile.txt");for(inti=0;i<5;i++){ }}}publicPrintWriter(OutputStreamout,booleanautoFlush)publicPrintWriter(Writerout,booleanautoFlush)*1*2publicclassPrintWriterDemo2publicstaticvoidmain(String[]args)throwsIOExceptionPrintWriterout=newPrintWriter(newFileWriter("printFile.txt"),for(inti=0;i<5;i++){ }}}導(dǎo)入加入classpath的第jar包內(nèi)的class文件才能在項(xiàng)目中使用lib文件夾commons-io.jarlibcommons-io.jar，BuildPath→AddtoBuildPathgetExtension(Stringpath)：獲取文件的擴(kuò)展名；itension(StringfileName,Stringext)：判斷fileName是否是ext后綴名readFileToString(File writeStringToFile(Filefile，Stringcontent)contentfilecopyDirectoryToDirectory(FilesrcDir,FiledestDir);文件夾copyFileToFile(FilesrcFile,FiledestFile);文件夾**publicclassCommonsIODemo01publicstaticvoidmain(String[]args)throwsIOException//method1("D:\\test.avi",通 FileUtils.copyFile(newFile("D:\\test.avi"),new}privatestaticvoidmethod1(Stringsrc,Stringdest)throwsIOException==byte[]buffer=newbyte[1024];intlen=-1;while((len=in.read(buffer))!=-1)out.write(buffer,0,}}}*publicclassCommonsIODemo02publicstaticvoidmain(String[]args)throwsIOException通 FileUtils.copyFile(newFile("D:\\test.avi"),new通通 到C:\\abc文件夾}}File("D:\\基礎(chǔ)班IOFileInputStreamObjectInputStreamFileOutputStreamBufferedOutputStreamObjectOuputStreamPrintStreamFileReaderBufferedReaderFileWriterBufferedWriterPrintWriterread()read(byte[]char[readObject()從流中對(duì)象(ObjectInputStream特有方法write(int)write(bytechar[write(String)writeObject(ObjectObjectOutputStream3，文件的過(guò)5，F(xiàn)ile FileFile判斷是否為文件 創(chuàng)建文件夾mkdir()創(chuàng)建文 throws異throw|load(InputStreaminload(Readerinstore(OutputStreamoutStringmessagestore(Writerout,Stringmessage)把集合中的數(shù)據(jù)，寫(xiě)入到流所對(duì)應(yīng)的文FileOutputStream(Filefile,booleanFileOutputStream(StringfileName,booleanFileWriter(File,booleanFileWriter(StringfileName,booleanPrintStream(OutputStreamout,booleanPrin