講義教程分析

9章工具類與算語言基礎(chǔ)類ObjectObject類是類庫中所有類的父類。有如下方法protectedObjectclone()生成當(dāng)前對象的一個拷貝，并返回這個對象publicbooleanequals(Objectobj) 同，是則返回truepublicfinalClassgetClass()獲取當(dāng)前對象所屬的類信息，Class對象protectedvoidfinalize() publicStringtoString() 數(shù)據(jù)類型數(shù)據(jù)類型類與基本數(shù)據(jù)類型密切相關(guān)。下面介紹Interger類構(gòu)造函數(shù)publicInteger(itnvalue)publics)可以分別利用一個基本數(shù)據(jù)類型int的量和一個字符串對象來生成一個Integer對象數(shù)據(jù)類型轉(zhuǎn)換方法分別將當(dāng)前對象所對應(yīng)的int量轉(zhuǎn)換成publicdoubledoubleValue()publicintintValue()publiclong字符串與int量相互轉(zhuǎn)化的方publicStringpublicstaticintparseInt(Strings)publicstaticIntegervalueOf(Strings)MathMath類的方法都是static的。publicfinalstaticdoubleE;數(shù)學(xué)常量epublicfinalstaticdoblePI;圓周率常publicstaticdoubleabs(doublea); publcistaticdoubleacos(doublea); publicstaticdoubleexp(doublea); //e的參數(shù)次冪publicstaticdoublefloor(doublea) publicstaticdoubleIEEEremainder(doublef1,double//求publicstaticdoublelog(double //自然對publicstaticdoublemax(doublea,doubleb); publicstaticfloatmain(floatafloatb) //最小值publicstaticdoublepow(doublea,doubleb) publicstaticdoublerandom() //01（不含）之間的publicstaticdoublerint(doublea) publicstaticdoublesqrt(doublea) SystemSystem類的屬性有三個標(biāo)準(zhǔn)輸入標(biāo)準(zhǔn)輸出和標(biāo)準(zhǔn)錯誤輸PublicstaticPrintStreamerr;PublicstaticImputStreamin;PublicstaticPrintStream數(shù)(1) 創(chuàng)建數(shù)組空數(shù)組名＝new類型[個數(shù)]intMy[]=newint[10];D200[]My=new如果是基本元素，則可省new并可同時給出初值intMy[]=初始要注意的問題有數(shù)組元素的下標(biāo)從0開始，至數(shù)組元素個數(shù)減1為所有數(shù)組元素有一個屬性length,表示數(shù)組元素的Java系統(tǒng)能自動檢查是否有數(shù)組下標(biāo)越界的情classpublicclassArraySize//Mainpublicstaticvoidmain(String[]args){Weeble[]a; Weeble[]b=newWeeble[5]; Weeble[]c=newWeeble[4];for(inti=0;i<c.length;i++) c[i]=newWeeble(); a=newWeeble[]{newWeeble(),new 并動態(tài)初始System.out.println("a.length="+a.length);System.out.println("b.length="+b.length);for(inti=0;i<b.length;i++)System.out.println("b["+i+"]"+b[i]);System.out.println("c.length="+c.length);System.out.println("d.length="+d.length);a=d;System.out.println("a.length="+int[]int[]f=newint[5];int[]g=newfor(inti=0;i<g.length;i++)g[i]=i*i;int[]h=//System.out.println("e.length="+e.length);System.out.println("f.length="+f.length);for(inti=0;i<f.length;i++)System.out.println("f["+i+"]="+f[i]);System.out.println("g.length="+g.length);System.out.println("h.length="+h.length);e=h;System.out.println("e.length="+e.length);e=newint[]{1,2};System.out.println("e.length="+e.length);}}向需要將不同類的對象組合成一個數(shù)據(jù)序需要做頻繁的對象序列中元素的插入和刪經(jīng)常需要定位序列中的對象或其他查找操在不同的類之間傳遞大量的數(shù)它的局限性是對象不能是簡單類型創(chuàng)建向量類的對象：publicVector(intinitCapacity,intinitCapacity表示剛創(chuàng)建時Vector序列包含的元素數(shù)capacityIncrement表示如果Vector序列中加元素，向向量序列中加元addElement(Object ement(Objectobj,int修改和刪 ementAt(Objectobj,intindex)removeElement(Objectobj)removeElementAt(intindex)查elementAt(intindex)contains(ObjectlastIndexOf(Objectobj,inta=a=字符字符串常量：StringString建一個無名的String類型對象。創(chuàng)建字符串常量String對String(Stringvalue)String(StringBufferbuffer)String(charvalue[])字符串常的操startsWith(Stringprefix)endsWith(Stringsuffix)字符串中單個字符的查indexOf(intindexOf(intch,int字符串中子串的查indexOf(Stringstr)indexOf(Stringstr,intfromIndex)lastIndexOf(Stringstr)lastIndexOf(Stringstr,int比較兩個字符compareTo(StringanotherString)equals(ObjectanObject)equalsIgnoreCase(StringanotherString)連接字符子concat(StringStringBuffer創(chuàng)建字符串變publicpublicStringBuffer(intlength)publicStringBuffer(Stringstr);publicStringBufferappend(Object)publicStringBufferinsert(int,Object)publicvoidsetCharAt(int,char)字符串的賦值和加=+遞遞歸的基本思想是自己調(diào)用自己參見如下的數(shù)列程 程序源代 說importjava.applet.Applet;importjava.awt.*;import {

Labelprompt=newLabel("ImportLength(LessthanTextFieldinput=newString[msg=new //創(chuàng)建長度50的字符串?dāng)?shù)組msg t=0; t=publicvoid{for(inti=0;i<50;i++)msg[i]="";}publicvoidpaint(Graphicsg{for(inti=0;i< t+ t+1;i++)g.drawString(msg[i],10,40+15*i);}publicvoidactionPerformed(ActionEvent{if(e.getSource(){t=t={}}}longFibonacci(int{longt t+ t]=Blanks( t)+"Fibonacci("+n+"):";{t t-1)+"Return"+n;returnn;}{歸計

temp=Fibonacci(n-1)+Fibonacci(n- t t-1)+"Return"+temp;return}}StringBlanks(intstepIn,int{Stringblank=for(inti=0;i<(stepIn-stepBack);i++)blank=blank+"";return}}了解以下各種排序和查找方法的基本思想冒泡排選擇排插入排桶排順序查對分查鏈class{privateintm_Data;privateNodem_Next;Node(int{m_Data=data;m_Next=null;}Node(intdata,Node{m_Data=data;m_Next=}voidsetData(int{m_Data=}int{return}voidsetNext(Node{m_Next=}Node{return}}class{Node{m_FirstNode=}LinkList(int{m_FirstNode=new}String{Nodenext=m_FirstNode;Strings="";while(next!={s=s+next.getData()+";";next=next.getNext();}return}voidinsertAtBegin(int{if(m_FirstNode==null)m_FirstNode=newNode(data);m_FirstNode=new}voidinsertAfterId(intdata,int{Nodenext=m_FirstNode;if(next==null)m_FirstNode=newNode(data);{while(next.getNext()!=null&&next.getData()!=id)next.setNext(newNode(data,}}booleanremoveAtId(int{Nodeahead=m_FirstNode;Nodefollow=ahead;returnelse{m_FirstNode=m_FirstNode.getNext();returntrue;}{ahead=ahead.getNext();{{returntrue;}follow=ahead=}return}}void{m_FirstNode=}}publicclassUseLinkList//Mainpublicstaticvoidmain(String[]{LinkListlist=newLinkList(-1);for(inti=0;i<10;i++){}System.out.println("Notexist");}}輸出10過異常處理錯異常與異常異常(Exception)和異常類是面向?qū)ο笠?guī)范的一部分異常類結(jié)構(gòu)與組所有Java異常類都是系統(tǒng)類庫中的Exception類的子java.lang包中的類Throwable類派生了兩個子類：Exception(應(yīng)用程序用)和Error（系統(tǒng)保留Exception的構(gòu)造函數(shù)有PublicPublicException(Strings提供錯誤描常用方法有publicString //返回錯誤描publicvoidprintStackTrace(); 系統(tǒng)定義的運(yùn)行異Exception有許多子類，每個子類代表一種特定的運(yùn)行時錯用戶自定義的異創(chuàng)建用戶自定義異常時，一般需要完成如下的工作一個新的異常類，父類為ExceptionclassEmptyQueueExceptionextendspublicStringtoString()classEmptyQueueExceptionextends{QueuePublicEmptyQueueException(Queue{super(“EmptyQueue”);sourceQueue=q;}publicString{}}10-1classSimpleExceptionextendsException{}publicclassSimpleExceptionDemo{publicvoidf()throws thrownew}//Mainpublicstaticvoidmain(String[]args){ try{}catch(SimpleExceptione){}}}10-classMyExceptionextendsException{publicMyException(){}publicMyException(Stringmsg){}}publicclassFullConstructorspublicstaticvoidf()throwsMyException{System.out.println("ThrowingMyExceptionfromf()");thrownewMyException();}publicstaticvoidg()throwsMyException{System.out.println("ThowingMyExceptionformg()");thrownewMyException("Originatedin}//Mainpublicstaticvoidmain(String[]args){try{}catch(MyExceptione){}try}

catch(MyExceptione){}}}輸出atuntitled1.MyException:Originateding()atuntitled1.FullConstructors.g(FullConstructors.java:20)atuntitled1.FullConstructors.main(FullConstructors.java:31)ThrowingMyExceptionfromf()ThowingMyExceptionform10-classMyException2extendsException{publicMyException2(){}publicMyException2(Stringmsg){}publicMyException2(Stringmsg,intx){i=}publicintval(){returni;}privateinti;}publicclassExtraFeaturespublicstaticvoidf()throwsMyException2{System.out.println("ThrowingMyException2fromf()");thrownewMyException2();}publicstaticvoidg()throwsMyException2{System.out.println("ThowingMyException2formg()");thrownewMyException2("Originateding()");}publicstaticvoidh()throwsMyException2{System.out.println("ThowingMyException2formh()");thrownewMyException2("Originatedinh()",47);}//Mainpublicstaticvoidmain(String[]args){try{}catch(MyException2e){}try}

catch(MyException2e){}try}catch(MyException2e){System.err.println("e.val()="+e.val());}}}輸出atatuntitled1.ExtraFeatures.main(ExtraFeatures.java:36)untitled1.MyException2:Originateding()atatuntitled1.ExtraFeatures.main(ExtraFeatures.java:42)untitled1.MyException2:Originatedinh()atatuntitled1.ExtraFeatures.main(ExtraFeatures.java:48)e.val()=47ThrowingMyException2fromf()ThowingMyException2formg()ThowingMyException2formh()拋出異Java程序在運(yùn)行時如果了一個可識別的錯誤就會系統(tǒng)自動拋出的異所有系統(tǒng)定義的運(yùn)行異常都可以由系統(tǒng)自動拋出。如語句拋出的異用戶自定義的異常必須錯助于throw語句來定義拋出intdequeue()throws{intifthrow(newEmptyQueueException(this));}必須注意以下兩個情況throw語句放if分支中，即滿足一定條件時拋出異含有throw語句的方法，應(yīng)該在方法頭中增加throws異常類名列異常的處捕捉異While{System.out.print(queue.dequeue()+“ //里可能會拋出異 }}catch(EmptyQueueException{}多異常的處catchtry后面，每個catch塊都有一個異常類捕捉所有異publicclassExceptionMethods//Mainpublicstaticvoidmain(String[]args){try{thrownewException("Here'smy}catch(Exceptione){ System.err.println("e.toString():"+e);}new}}輸出CaughtExceptione.getMessage():Here'smyExceptione.getLocalizedMessage():Here'smye.toString():java.lang.Exception:Here'smyExceptionjava.lang.Exception:Here'smyException重新拋出異publicclassRethrowingpublicstaticvoidf()throwsException{System.out.println("fromf()");thrownewException("ThowingExceptionform}publicstaticvoidg()throwsThrowable{}catch(Exception //如果這兩句修改則輸出為輸出//throw}}//Mainpublicstaticvoidmain(String[]args)throwsThrowable{try{}catch(Exceptione) }}}輸出g(),java.lang.Exception:ThowingExceptionformf()atuntitled1.Rethrowing.f(Rethrowing.java:9)atuntitled1.Rethrowing.g(Rethrowing.java:14)atCaughtinmain,e.printStackTrace()java.lang.Exception:ThowingExceptionformf()atuntitled1.Rethrowing.f(Rethrowing.java:9)atuntitled1.Rethrowing.g(Rethrowing.java:14)atuntitled1.Rethrowing.main(Rethrowing.java:26)fromf()Insideg(),e.printStackTrace()java.lang.Exception:Thowingformf()atuntitled1.Rethrowing.f(Rethrowing.java:9)atuntitled1.Rethrowing.g(Rethrowing.java:14)atuntitled1.Rethrowing.main(Rethrowing.java:26)Caughtinmain,e.printStackTrace()java.lang.Exception:Thowingformf()atatuntitled1.Rethrowing.main(Rethrowing.java:26)Originatingtheexceptioninf()因?yàn)閒illInStackTrace()的緣故，改變了異常的classOneExceptionextendspublicOneException(Strings)}classTwoExceptionextendsException{publicTwoException(Strings){super(s);}}publicclassRethrowNewpublicstaticvoidf()throwsOneException{System.out.println("Originatingtheexceptioninf()");thrownewOneException("thrownfromf()");}//Main try}catch(OneExceptione) thrownewTwoException("from}}}輸出Caughtinmain,e.printStackTrace()untitled1.OneException:thrownfromf()atuntitled1.TwoException:frommain()atuntitled1.RethrowNew.main(RethrowNew.java:28)Exceptioninthread"main"Originatingtheexceptioninf()最后一個只拋出，沒有截取的，回收器負(fù)責(zé)清Java標(biāo)準(zhǔn)異Throwable有兩類：Error和Exception.Error無需捕捉，代表編譯期錯誤和系統(tǒng)錯誤Exception代表可能從(1)Java標(biāo)準(zhǔn)程序庫內(nèi)，(2)用戶函數(shù)執(zhí)行期發(fā)生的意外事RuntimeException可以一路傳遞直至finally進(jìn)行清無論是否拋出異常，finally子句都會被執(zhí)行classThreeExceptionextendsException{}publicclassFinallyWorks{staticintcount=//Mainpublicstaticvoidmain(String[]args){while(true){tryif(count++==0) thrownewThreeException();System.out.println("Noexception");}catch(ThreeExceptione){}System.err.println("Infinallyclause");if(count==2)break;}}}}InfinallyclauseInfinallyclauseNoexception不管有沒有異常，finally是一定要做異常遺classVeryImportantExceptionextendsException{publicStringtoString(){return"Averyimportant}}classHoHumExceptionextendsException{publicStringtoString(){return"Atrivial}}publicclassLostMessagevoidf()throwsthrownew}voiddispose()throwsHoHumException{thrownewHoHumException();}//Mainpublicstaticvoidmain(String[]args)throwsException{LostMessagelm=newLostMessage();}}}輸出Atrivialatuntitled1.LostMessage.dispose(LostMessage.java:22)atuntitled1.LostMessage.main(LostMessage.java:30)Exceptioninthread沒有出現(xiàn)VeryImportantException,第二個異常HoHumException在第一個異常處理之前拋11JavaI/O系Java輸入輸出類java的輸入輸出功能通過輸入輸出類庫java.io包實(shí)現(xiàn)Java.io中有一個類（File）專門用于文件系統(tǒng)交互BooleancanRead();BooleancanWrite();Booleanexitsts();StringgetAbsolutePath();BooleanisFile();BooleanisDirectory();Booleanlength();BooleancreateNewFile();Booleandelete();VoiddeleteOnExit();//程序運(yùn)行結(jié)束時刪除該文Boolean流的概流式輸入輸出的特點(diǎn)是：數(shù)據(jù)的獲取和發(fā)送是順序的數(shù)據(jù)可以是二進(jìn)制，字符，數(shù)字等輸入輸出流基本輸入輸出InputStream類是抽象類，具體對象是它的子類對象publicintread(以二進(jìn)制方式讀publicintread(byteb[]); publiclongskip(longn);//n個字節(jié)publicvoidmark(); publicvoidreset(); publicvoidclose(); OutputStream類是抽象類，具體對象是它的子類對主要方法有publicintwrite(intb);//將參b的低位字節(jié)寫入publicintwrite(byteb[]); //將參數(shù)b中的全部字publicvoidflush(); publicvoid //關(guān)閉幾種具體輸入輸出過濾 文件：FileInputStream,管道 FilterInputStream,和FilterOutputStream的子類： ReadByte(),readBoolean(),readShort(),…….WriteByte(),writeInt(),……標(biāo)準(zhǔn)輸入輸標(biāo)準(zhǔn)輸System.in.read()要注意try中，可接收異讀一個字節(jié)的數(shù)據(jù)，返回16位值，高80，且只能如鍵盤緩沖區(qū)沒有值，則進(jìn)程掛起ch= //從鍵盤緩沖區(qū)讀入字節(jié)的數(shù)據(jù)}catch(IOExceptione)標(biāo)準(zhǔn)輸System.out.println(“Pressanykeytofinishtheprogram”);charrest=}catch(IOException程序?qū)嵗齣mportjava.io.*;publicclassInAndOut{publicstaticvoidmain(String{BufferedReaderin s=in.readLine();}catch(IOExceptionSystem.out.println("Youareenteredstring:"+}}文件的處理與隨Java程序的文件與管File類的對象表示一個磁盤文件或，其對象屬性中包含了文件或的相關(guān)信息，如名稱，長度，所含文可以是絕對，相對，靜態(tài)屬性System.dirSep作File類的對構(gòu)造函數(shù)File(String 例如Filef1=newStrings=Filef2=newnewFile(Stringpath,String// 與名稱分開的方例如Filef3=File(“myProgram\Java”,File(Filedir,String例如Stringsdir=“myProgram”+System.dirSep+”Java”;Stringsfile=“FileIO.data”;FileFdir=newFileFfile=new publicbooleanexists() publicbooleanisFIle() //publicbooleanisDirectory() publicStringgetName() publicStringgetPath()//publiclonglength()publicbooleancanRead()publicbooleancanWrite()publicString[]list();publicbooleanequals(File文件 操publicbooleanrenameTo(FilenewFile)publicvoiddelete()publicboolean程序?qū)嵗齣mportpublicclassFileOperation//Mainpublicstaticvoidmain(Stringargs[]{try Stringsdir="e:\\temp";Stringsfile;FileFdir1=newFile(sdir);if(Fdir1.exists()&&Fdir1.isDirectory()){System.out.println("Thereisadirectory"++"for(inti=0;i<Fdir1.list().length;i++)FileFdir2=newFile("e:\\temp\\temp"); createanewdir:");for(inti=0;i<Fdir2.list().length;i++)} sfile=FileFfile=newFile(Fdir1,sfile);{System.out.println("File"+Ffile.getName()+"inPath"+Ffile.getPath()+"is"+Ffile.length()+"in}}catch(Exceptione){}}}文件輸入輸出FileInputStream利用文件名字符串或File對象創(chuàng)建輸入輸出流對FileInputStream(StringFileInputStream(File利用已File對象創(chuàng)建從該對象對應(yīng)的磁盤從文件輸入輸出流中讀寫數(shù)FileMyFile=new DataOutputStreamdout=newDataOutputStream(new程序?qū)嵗齣mportjava.io.*;publicclassMyFileIo{//Mainpublicstaticvoidmain(String[]args){charch;intFileMyPath=newFile("\\temp");FileMyFile1=newFile(MyPath,"crt.txt");try{ System.out.println("InputaStringfinishedwith#while((ch=(char)System.in.read())!='#')FileInputStreamfin=newFileInputStream(MyFile1);while((chi=fin.read())!=-1)}catch(FileNotFoundExceptione){}catch(IOExceptione){}}}程序?qū)ξ募碾SRandomAccessFile對象RandomAccessFile(StringnameStringmode);RandomAccessFile(Filef,Stringmode);FileBackMegFile=newFile(“BankFile.txt”); 對文件位置指針的操RandomAccessFile對象的文件位置指針位于文件每次讀寫操作后文件位置指針相應(yīng)后移讀寫的字longgetPointer()方法可得到當(dāng)前文件位置指針?biāo)趘oidseek(longpos)可移動文件位置指針用longlength()可返回文件的字節(jié)長度讀操實(shí)現(xiàn)DataInput接口，RandomAccessFile中的讀方法 readFloat(),readDouble(),readLine(),readUTF().寫操RandomAccessFile 程序?qū)嵗齣mportimportjava.awt.event.*;importjava.awt.*;publicclassTestFileDialogpublicstaticvoidmain(String[]args){newFileFrame();}}classFileFrameextendsFrameimplements{TextAreata;Buttonopen,quit;FileDialogfd;{super("Acquireanddisplaytext");ta=newTextArea(10,45);open=newButton("Open");quit=newButton("Close");setLayout(newFlowLayout());}publicvoidactionPerformed(ActionEvent{ { Filemyfile=newFile(fd.getDirectory(),fd.getFile()); {ta.append(raf.readLine()+}}catch(IOException{}} {}}}第12章網(wǎng)絡(luò)編基于連接的流式套接套接字(Socket)是TCP/IP協(xié)議的編程接口，通過提供的一組APITCP/IP協(xié)議InetAddressInetAddress類對象中包含了IP地址，主機(jī)名等的IP地址。程序?qū)嵗齣mportpublicclassMyIPAddresspublicstaticvoidmain(String[]args){try{if(args.length{ }}catch(UnknownHostExceptione)}}}Socket是基于連接的通信，在通信開始之前由通信雙方確認(rèn)并建立一條的虛擬連接通道，通信結(jié)束后SocketServerSocket創(chuàng)建一個ServerSocket對象就創(chuàng)建了一個服務(wù)，創(chuàng)建了一個Socket對象就建立了一個ClientServer間的連ServerSocket類//提供服務(wù)的端為SocketLinkSocket=//Server等待直到捕捉到來自Client端的請并返回Socket對象LinkSocket,用于寫數(shù)據(jù)。//Socket類 puterName”,8000);//欲連接的主機(jī)地址，提供服務(wù)的端 創(chuàng)建Socket對象，向Server 端口請Socket中讀寫Server端通信Client創(chuàng)建Socket對象，向Server 端口請Socket中讀寫Server端通信Client ServerSock對象在 Socket中讀寫數(shù)據(jù)Client端通信接收ClientSocket建立連接Client端的服務(wù)Server關(guān)閉Socket,關(guān)閉關(guān)閉ServerSocket對象結(jié) 實(shí)現(xiàn)流式Socket通信的ClientServer端編程序?qū)嵗?/Server端程importjava.io.*;importjava.awt.*;import.*;importpublicclassMySocketServerpublicstaticvoidmain(String[]{ }}classServiceThreadextendsFrameimplements{ServerServiceFatherListener;SocketConnectedClient;ThreadConnectThread;PanelListenerPanel;TextAreaServerMeg;publicServiceThread(ServerServicesv,Socket{FatherListener=sv;ConnectedClient=s;ConnectThread=newThread(this);setTitle("AnswerClient");setLayout(newBorderLayout());ServerMeg=newTextArea(10,50);add("Center",ServerMeg); ClientAddress.toString()+"\n");}publicvoid{DataInputStreamin=newDataInputStream(new

econnecttoourStrings=in.readLine();{ServerMeg.append("ClientInputInfo:\n"+s);s=in.readLine();}}catch(Exceptione){}FatherListener.addMeg("Client"+"closed."+"\n");}}classServerServiceextends{ServerSocketpublicServerService(intPort,int{try m_sListener=newServerSocket(Port,Count);m_sListener=newServerSocket(Port);setTitle("ServerListener");this.addWindowListener(newWinAdpt());setLayout(newBorderLayout());

add("Center",ListenerMeg);{SocketConnected=m_sListener.accept(); ListenerMeg.append("Client"+"connected"+"from\n"+ClientAddress.toString()+".\n");}}}}

ServiceThreadMyST=newcatch(IOException}publicvoidaddMeg(String{}}classWinAdptextends{publicvoidwindowClosing(WindowEvent{}//Client端程序importjava.io.*;importjava.awt.*;import.*;importclassMyClientextendsFrameimplements{SocketClientSocket;PrintStreamos;DataInputStreamis;Strings;LabelMylabel=newLabel(" e");TextAreatextArea;ButtonMyButton=newpublicstaticvoidmain(String{newpublic{setTitle("ClientWindow");setLayout(newBorderLayout());this.addWindowListener(newWinAdptClient(this));textArea=newTextArea(20,50);add("Center",textArea);}publicvoid{ClientSocket=new s=is.readLine();}catch(Exception}publicvoidactionPerformed(ActionEvent{{}catch(Exception}}}classWinAdptClientextends{MyClientm_Parent;WinAdptClient(MyClientp){m_Parent=}publicvoidwindowClosing(WindowEvent{try}catch(Exception}}無連接的數(shù)據(jù)數(shù)據(jù)Socket又稱UDP套接字直接將信息打包傳向指DatagramPacketDatagramSocketDatagramPacket類：用于數(shù)PublicDatagramPacket(byteibuf[],int InetAddressiaddr,intiport)（I，目的地的端口）DatagramSocket類：用于實(shí)現(xiàn)數(shù)據(jù)報的發(fā)送和接收過PublicPublicDatagramSocket(int UDP的編程實(shí)數(shù)據(jù)報的發(fā)送過程DatagramPacket對提供要發(fā)送的數(shù)據(jù)數(shù)據(jù)報分組長度發(fā)送目的機(jī)地址和目的端在指定的或可用的本機(jī)端口創(chuàng)建DatagramSocket對象DatagramSocket.send()數(shù)據(jù)報的接收過程DatagramPacket對象DatagramSocket對importjava.io.*;.*;publicclassUDPServerService//Mainpublicstaticvoidmain(String[]args){{System.out.println("Pleaseinputlocal}UDPServerThreadMyUDPServer=new}}classUDPServerThrea