第4天properties、序列化流commonsio与反

17IOPropertiescommons-Properties1、Hashtable的子类，mapload(InputStream)把指定流所对应的文件中的数据出来，保存到Propertie集合，， commonts *Properties集合，它是唯一一个能与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，完成把集合内容到IO流所对应文件中的操作1Properties publicpublicclassPropertiesDemo02publicstaticvoidmain(String[]args)throwsIOException//1，创建PropertiesPropertiesprop=new "," ", ", FileWriterout=new prop.store(out,"save}}perties中取出数据，保存到集合中3,把流所对应文件中的数据到集合 把指定流所对应的文件中的数据，出来，保存到Propertie集合publicclasspublicclassPropertiesDemo03publicstaticvoidmain(String[]args)throwsIOExceptionPropertiesprop=newFileInputStreamin=new//FileReaderin=new }}用于从流中对象的操作流ObjectInputStream 称为反序列化流用于向流中写入对象的操作流 称为序列化ObjectOutputStream将Java对象的基本数据类型和图形写入OutputStream。可以使用ObjectInputStream（重构）对象。通过在流中使用文件可以实现对象的持久。注意：只能将支持java.io.Serializable接口的对象写入流中publicpublicclassObjectStreamDemo ClassNotFoundException*将一个对 publicpublicimplementsSerializableprivateStringprivateint}()(Stringname,intage)=this.age=}publicStringgetName()return}publicvoidsetName(Stringname)=}publicintgetAge()return}publicvoidsetAge(intage)this.age=}publicStringtoString()return [name="+name+",age="+age+}}类}publicstaticvoidwriteObj()throwsIOException FileOutputStreamfos=newObjectOutputStreamoos=new }}ObjectInputStream对以前使用ObjectOutputStream写入的基本数据和对象进行反序列化。支持java.io.Serializable接口的对象才能从流。publicpublicclassObjectStreamDemo ClassNotFoundException}publicstaticvoidreadObj()throwsIOException,ClassNotFoundException FileInputStreamfis=new ObjectInputStreamois=newobj=}}当一个对象要能被序列化，这个对象所属的类必须实现Serializable化也会发生异常InvalidClasception。发生这个异常的原因如下：Serializable标记接口。该接口给需要序列化的类，提供了一个序列版本号。serialVersionUID.该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修饰了，序列化时这个属性就不会琲序列化了。public*public*implementsSerializableprivatestaticfinallongserialVersionUID=privatestaticStringprivatetransient/*瞬态*int ()} (Stringname,intage)=name;this.age=age;}publicStringgetName()return}publicvoidsetName(Stringname)=}publicintgetAge()return}publicvoidsetAge(intage)this.age=}publicStringtoString()return[name="+name+",age="+age+}}字节打印流字符打印流voidprint(Stringstr):voidprintln(Stringstr):需求：把指定的数据，写入到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++){ }}}导入加入classpath的第jar包内的class文件才能在项目中使用lib文件夹commons-io.jarlibcommons-io.jar，BuildPath→AddtoBuildPathgetExtension(Stringpath)：获取文件的扩展名；itension(StringfileName,Stringext)：判断fileName是否是ext后缀名readFileToString(File writeStringToFile(Filefile，Stringcontent)contentfilecopyDirectoryToDirectory(FilesrcDir,FiledestDir);文件夹copyFileToFile(FilesrcFile,FiledestFile);文件夹**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文件夹}}File("D:\\基础班IOFileInputStreamObjectInputStreamFileOutputStreamBufferedOutputStreamObjectOuputStreamPrintStreamFileReaderBufferedReaderFileWriterBufferedWriterPrintWriterread()read(byte[]char[readObject()从流中对象(ObjectInputStream特有方法write(int)write(bytechar[write(String)writeObject(ObjectObjectOutputStream3，文件的过5，File FileFile判断是否为文件 创建文件夹mkdir()创建文 throws异throw|load(InputStreaminload(Readerinstore(OutputStreamoutStringmessagestore(Writerout,Stringmessage)把集合中的数据，写入到流所对应的文FileOutputStream(Filefile,booleanFileOutputStream(StringfileName,booleanFileWriter(File,booleanFileWriter(StringfileName,booleanPrintStream(OutputStreamout,booleanPrin