java ppt -16new

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1、IntroductiontoJavaProgrammingLecture16NetworkProgramminginJavaObjectives16-2•PerformnetworkI/Ousingthecoreclassesinthepackagejava.net•WriteprogramsthatestablishconnectionstoURLsandperformstreamI/ObetweenURLs•Readandwritedatatolocalandremotesitesusing

2、streamsocketsanddatagramsocketsIntroductiontoJavaProgrammingTCP/IP16-3TelnetFTPHTTPSMTP…应用层套接字SocketTCP/UDP传输层IP/ICMP网络互联层数据链路层与物理层低层IntroductiontoJavaProgrammingPort16-4port：Networkedcomputerhasmany(virtual)wiresthatleadtothenetportnumber:inTCP/IPsy

3、stemsare16bitnumbers(range0-65535).Inpractice,portnumberbelow1024arereservedforpre-definedservices应用程序2TelnetHTTP应用程序1FTP应用程序3echo应用程序SMTP4Port18021Port223Port37Port425TCP/IPTCP/IP或UDP或UDPPortNumb.80DataDataDatagramDatagramIntroductiontoJavaProgrammi

4、ngSocket16-5•Socketisthenamegiven,inoneparticularprogrammingmodel,totheendpointsofcommunicationlinksbetweenprocesses•Whenprocesscommunicateoveranetwork,Javauseitsstreamsmodel.Asocketholdstwostreams,oneinputstreamandoneoutputstream•Aprocesssendsdatato

5、theotherprocessviathenetworksimplybywritingtotheoutputstreamassociatedwiththesocket•Theprocessreadsdatathatwerewrittenbytheprocessatthe“otherend”oftheconnectionsimplybyreadingfromtheinputstreamassociatedwiththesocketIntroductiontoJavaProgrammingClien

6、t/ServerCommunication16-6SeverClientdatadataSocketSocket面向连接的Client/Server通信datadataSeverClientSocketSocket面向无连接的Client/Server通信IntroductiontoJavaProgrammingNetworkProgramminginJava16-7•OneofJava’sgreateststrengthsisitssupportfornetworkprogramming•Th

7、ejava.netpackageprovidesclassesthatfacilitatenetworkprogrammingataveryhighlevelofabstractionIntroductiontoJavaProgrammingJava.net16-8•java.net.URL•java.net.URLConnection•java.net.InetAddress•java.net.ServerSocket•java.net.Socket•java.net.DatagramSock

8、et•java.net.DatagramPacketIntroductiontoJavaProgrammingInetAddress16-9•IdentifyingHosts–InordertocommunicatewithotherhostsoveranIPnetwork,wefirstneedtoknowtheirIPaddresses–Java’sInetAddressclassisusedtorepresentIPaddresses•Noexplictconstructor,usethr