第一講??? ?概述?
1、網(wǎng)絡(luò)模型：OSI參考模型和TCP/IP參考模型
圖示：
??????? 一般來(lái)說(shuō)開(kāi)發(fā)處于傳輸層和網(wǎng)際層，應(yīng)用層為：FTP和HTTP協(xié)議等，傳輸層為：UDP和TCP等，網(wǎng)際層為：IP。
??????? 通常用戶(hù)操作的是應(yīng)用層，而編程人員需要做的是傳輸層和網(wǎng)際層，用戶(hù)在應(yīng)用層操作的數(shù)據(jù)，經(jīng)過(guò)逐層封包，最后到物理層發(fā)送到另一個(gè)模型中，再進(jìn)行逐層解包，圖示為：
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2、網(wǎng)絡(luò)通信三要素：IP地址，端口號(hào)，傳輸協(xié)議
A、IP地址
??????? a、它是網(wǎng)絡(luò)中的設(shè)備標(biāo)識(shí)
??????? b、不易記憶，可用主機(jī)名表示，兩者存在映射關(guān)系
??????? c、本機(jī)回環(huán)地址：127.0.0.1，主機(jī)名為：localhost。
IP地址：java中對(duì)應(yīng)的是InetAddress類(lèi)，存在于java.net包中。
InetAddress類(lèi)：
???? （一）無(wú)構(gòu)造函數(shù)，可通過(guò)getLocalHost()方法獲取InetAddress對(duì)象，此方法是靜態(tài)的，返回本類(lèi)對(duì)象。
??????????????????InetAddress i = InetAddress.getLocalHost();
???? （二）方法：
??????????????? 1）static InetAddress getByName(String host)：獲取指定主機(jī)的IP和主機(jī)名。（最好用ip地址去獲取，主機(jī)名需要解析）
??????????????? 2）static InetAddress[] getAllByName(String host)：在給定主機(jī)名的情況下，根據(jù)系統(tǒng)上配置的名稱(chēng)服務(wù)返回IP地址所組成的數(shù)組。返回對(duì)象不唯一時(shí)，用此方法。
??????????????? 3）String getHostAddress()：返回IP地址字符串文本形式，以IP地址為主。
??????????????? 4）String getHostName()：返回IP地址主機(jī)名。
???? （三）如何獲取任意一臺(tái)主機(jī)的IP地址對(duì)象：
??????????????? 1）功能：返回InetAddress對(duì)象
??????????????? 2）對(duì)于任意主機(jī)，需要指定傳入主機(jī)名的參數(shù)
注意：如果IP地址和對(duì)應(yīng)的主機(jī)名，這種映射關(guān)系沒(méi)有在網(wǎng)絡(luò)上，就不會(huì)解析成功，返回的還是指定的IP。
示例：
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import?java.net.*;??class?IPDemo???{??????public?static?void?main(String[]?args)throws?Exception???????{??????????????????InetAddress?ia=InetAddress.getLocalHost();????????????????????????????String?address=ia.getHostAddress();??????????????????String?name=ia.getHostName();??????????System.out.println("IP="+address+"\tname="+name);????????????????????InetAddress?i=InetAddress.getByName("192.168.1.175");????????????String?add=i.getHostAddress();??????????String?na=i.getHostName();??????????System.out.println("addIP="+add+"\tiname="+na);????????????????????InetAddress[]?baidu=InetAddress.getAllByName("www.baidu.com");??????????for?(InetAddress?b?:baidu)??????????{??????????????String?baddress=b.getHostAddress();??????????????String?bname=b.getHostName();??????????????System.out.println("baiduIP="+baddress+"\tbaiduname="+bname);??????????}??????}??}?? B、端口號(hào)：
??????? a、用于標(biāo)識(shí)進(jìn)程的邏輯地址，不用進(jìn)程的標(biāo)識(shí)。
??????? b、有效端口：0 ~65535，系統(tǒng)使用或保留的端口是：0~ 1024。
C、傳輸協(xié)議：
??????? 即通信規(guī)則，包含TCP和UDP協(xié)議
UDP
??????? 是面向無(wú)連接，明確了對(duì)方的端口，無(wú)論在不在網(wǎng)上，只管傳輸，不在就會(huì)丟失數(shù)據(jù)。只求速度，應(yīng)用于網(wǎng)絡(luò)視頻會(huì)議和聊天等應(yīng)用程序中。
協(xié)議特點(diǎn)：
???????? a、面向無(wú)連接，即將數(shù)據(jù)及源和目的封裝成數(shù)據(jù)包中，不建立鏈接的發(fā)送
???????? b、每個(gè)數(shù)據(jù)包的大小限制在64K之內(nèi)
???????? c、因無(wú)連接，是不可靠的協(xié)議
???????? d、不建立連接，速度快。
TCP
??????? 是面向連接的，必須連接成功才能傳輸數(shù)據(jù)，應(yīng)用于下載等程序上
協(xié)議特點(diǎn)：
???????? a、面向連接，在建立連接后，形成傳輸數(shù)據(jù)的通道
???????? b、在連接中進(jìn)行大數(shù)據(jù)量的傳輸
?????????c、通過(guò)三次握手完成連接，是可靠的協(xié)議
???????? d、必須建立連接，效率稍慢
三次握手：第一次本方發(fā)送請(qǐng)求，第二次對(duì)方確認(rèn)連接，第三次本方再次確認(rèn)連接成功。
3、通信的步驟：
??????? 1）找到IP地址
??????? 2）數(shù)據(jù)要發(fā)送到對(duì)象指定應(yīng)用程序，為標(biāo)識(shí)這些應(yīng)用程序，所以給這些網(wǎng)絡(luò)應(yīng)用程序都用數(shù)字標(biāo)識(shí)，為方便稱(chēng)呼這個(gè)數(shù)字，叫做端口，即邏輯端口。
??????? 3）定義通信規(guī)則，稱(chēng)之為協(xié)議。國(guó)際組織定義了通用協(xié)議，即TCP/IP。
注意：必須要有數(shù)字標(biāo)識(shí)才能將數(shù)據(jù)發(fā)送到應(yīng)用程序上。
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第二講?????傳輸協(xié)議
一、Socket
??????? 1、它被稱(chēng)之為插座，相當(dāng)于港口一樣，是網(wǎng)絡(luò)服務(wù)提供的一種機(jī)制。
??????? 2、通信兩端都要有Socket，才能建立服務(wù)。
??????? 3、網(wǎng)絡(luò)通信其實(shí)就是Socket間的通信，數(shù)據(jù)在兩個(gè)Socket間通過(guò)IO傳輸。
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二、UDP傳輸
1、通過(guò)類(lèi)DatagramSocket，此類(lèi)表示用發(fā)送和接收數(shù)據(jù)包的套接字，即Socket。
2、方法：
??????? 1）創(chuàng)建?UDPSocket發(fā)送服務(wù)對(duì)象：
????????????? DatagramSocket()，不指定端口。DatagramSocket(int port)，指定端口。
??????? 2）發(fā)送：void send(DatagramPacket p)
??????? 3）接收：void receive(DatagramPacket p)
???????其中DatagramPacket：數(shù)據(jù)報(bào)包用來(lái)實(shí)現(xiàn)無(wú)連接包投遞服務(wù)的，每條報(bào)文僅根據(jù)該包中包含的信息從一臺(tái)機(jī)器路由到另一臺(tái)機(jī)器中。凡是帶地址（InetAddress）的都是用于發(fā)送包的。
3、步驟
??????? 1）發(fā)送數(shù)據(jù)：
????????????? a、建立UDPSocket服務(wù)，在此無(wú)需指定端口，也可以將端口加入。如果不指定的話(huà)，系統(tǒng)會(huì)隨機(jī)分配一個(gè)端口，如第一次運(yùn)行時(shí)端口為1093，那么第二次就會(huì)順延為1094，再運(yùn)行會(huì)一直順延，因?yàn)橹暗亩丝谶€沒(méi)有得到釋放，所以會(huì)順延端口號(hào)值。
????????????? b、提供數(shù)據(jù)，并將數(shù)據(jù)封裝到數(shù)據(jù)包中
????????????? c、通過(guò)socket服務(wù)的發(fā)送功能，將數(shù)據(jù)包發(fā)送出去
????????????? d、關(guān)閉資源
??????? 2）接收數(shù)據(jù)：
????????????? a、定義UDPSocket服務(wù)。通常會(huì)監(jiān)聽(tīng)一個(gè)端口，其實(shí)就是給這個(gè)接收網(wǎng)路應(yīng)用程序定義數(shù)字標(biāo)識(shí)，方便于明確哪些數(shù)據(jù)過(guò)來(lái)該應(yīng)用程序可以處理。
????????????? b、定義一個(gè)數(shù)據(jù)包，用來(lái)存儲(chǔ)接收到的字節(jié)數(shù)據(jù)，因?yàn)閿?shù)據(jù)包對(duì)象中有更多功能可以提取字節(jié)數(shù)據(jù)中的不同數(shù)據(jù)信息。
????????????? c、通過(guò)socket服務(wù)的receive方法接收到的數(shù)據(jù)存入已定義好的數(shù)據(jù)包中傷感的句子
????????????? d、通過(guò)數(shù)據(jù)包對(duì)象的特有功能，將這些不同的數(shù)據(jù)取出，打印在控制臺(tái)上
??????????????e、關(guān)閉資源
????????在定義接收數(shù)據(jù)的方法中，仍會(huì)在DatagramSocket構(gòu)造函數(shù)中傳入DatagramPacket的參數(shù)，這是因?yàn)槭盏降臄?shù)據(jù)太多，需要解析，通過(guò)將數(shù)據(jù)封裝成對(duì)象，易于解析，所以需要傳入?yún)?shù)。
注意：
??????? 1、發(fā)送端與接收端是兩個(gè)獨(dú)立的運(yùn)行程序。
????????2、在發(fā)送端，要在數(shù)據(jù)包對(duì)象中明確目的地IP及端口。
??????? 3、在接收端，要指定監(jiān)聽(tīng)的端口。
示例：
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??import?java.net.*;??class?UdpSend???{??????public?static?void?main(String[]?args)throws?Exception???????{??????????????????DatagramSocket?ds=new?DatagramSocket();??????????????????byte[]?buf="udp?shi?shen?ma".getBytes();??????????DatagramPacket?dp=new?DatagramPacket(buf,buf.length,InetAddress.getByName("192.168.1.175"),10000);????????????????????ds.send(dp);??????????????????ds.close();??????}??}??????class?UdpReceive??{??????public?static?void?main(String[]?args)throws?Exception??????{????????????????????????????????????????????while(true)??????????{??????????????????????????DatagramSocket?ds=new?DatagramSocket(10000);??????????????????????????byte[]?buf=new?byte[1024];??????????????DatagramPacket?dp=new?DatagramPacket(buf,buf.length);??????????????????????????ds.receive(dp);????????????????????????String?ip=dp.getAddress().getHostName();??????????????String?data=new?String(dp.getData(),0,dp.getLength());??????????????int?port=dp.getPort();??????????????System.out.println(ip+"::"+data+"::"+port);??????????????????????????ds.close();??????????}??????????????????????}??}?? 練習(xí)一
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??import?java.net.*;??import?java.io.*;??class?UdpSend????{??????public?static?void?main(String[]?args)throws?Exception??????{??????????????????DatagramSocket?ds=new?DatagramSocket(9999);??????????????????DatagramPacket?dp=null;??????????BufferedReader?br=new?BufferedReader(new?InputStreamReader(System.in));??????????String?line=null;??????????while((line=br.readLine())!=null)??????????{??????????????byte[]?buf=line.getBytes();??????????????dp=new?DatagramPacket(buf,buf.length,InetAddress.getByName("192.168.1.255"),10000);??????????????????????????ds.send(dp);??????????????if?("886".equals(line))??????????????{??????????????????break;??????????????}??????????}??????????????????ds.close();????????????????}??}????class?UdpReceive??{??????public?static?void?main(String[]?args)throws?Exception??????{??????????????????DatagramSocket?ds=new?DatagramSocket(10000);??????????????????while?(true)??????????{??????????????????????????byte[]?buf=new?byte[1024];??????????????DatagramPacket?dp=new?DatagramPacket(buf,buf.length);??????????????????????????ds.receive(dp);??????????????????????????String?ip=dp.getAddress().getHostAddress();??????????????String?data=new?String(dp.getData(),0,dp.getLength());??????????????int?port=dp.getPort();????????????????System.out.println("IP:"+ip+"=="+data);??????????}??????????????????????}??}????? 練習(xí)二
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??import?java.net.*;??import?java.io.*;????class?UdpSend?implements?Runnable??{??????????private?DatagramSocket?ds;??????UdpSend(DatagramSocket?ds)??????{??????????this.ds=ds;??????}??????????public?void?run()??????{??????????try??????????{??????????????????????????DatagramPacket?dp=null;??????????????BufferedReader?br=new?BufferedReader(new?InputStreamReader(System.in));??????????????String?line=null;??????????????while((line=br.readLine())!=null)??????????????{??????????????????byte[]?buf=line.getBytes();??????????????????dp=new?DatagramPacket(buf,buf.length,InetAddress.getByName("192.168.1.255"),10000);??????????????????????????????????ds.send(dp);??????????????????if?("886".equals(line))??????????????????{??????????????????????break;??????????????????}??????????????}??????????????????????????ds.close();??????????}??????????catch?(Exception?e)??????????{??????????????throw?new?RuntimeException("發(fā)送數(shù)據(jù)失敗");??????????}?????????????}??}????class?UdpReceive?implements?Runnable??{??????????private?DatagramSocket?ds;??????UdpReceive(DatagramSocket?ds)??????{??????????this.ds=ds;??????}??????????public?void?run()??????{??????????try??????????{??????????????????????????while?(true)??????????????{??????????????????????????????????byte[]?buf=new?byte[1024];??????????????????DatagramPacket?dp=new?DatagramPacket(buf,buf.length);??????????????????????????????????ds.receive(dp);??????????????????????????????????String?ip=dp.getAddress().getHostAddress();??????????????????String?data=new?String(dp.getData(),0,dp.getLength());??????????????????int?port=dp.getPort();????????????????????System.out.println("IP:"+ip+"=="+data);??????????????}??????????????????????????????????}??????????catch?(Exception?e)??????????{??????????????throw?new?RuntimeException("接收端接收數(shù)據(jù)失敗");??????????}??????}??}????class?UdpChatDemo??{??????public?static?void?main(String[]?args)throws?Exception??????{??????????new?Thread(new?UdpSend(new?DatagramSocket())).start();??????????new?Thread(new?UdpReceive(new?DatagramSocket(10000))).start();??????}??}?? 三、TCP傳輸
1、TCP分客戶(hù)端和服務(wù)端。客戶(hù)端對(duì)應(yīng)的對(duì)象是Socket，服務(wù)端對(duì)應(yīng)的對(duì)象是ServerSocket。
2、方法：
??????? 1）創(chuàng)建客戶(hù)端對(duì)象：
??????????????Socket()：創(chuàng)建空參數(shù)的客戶(hù)端對(duì)象，一般用于服務(wù)端接收數(shù)據(jù)
????????????? Socket(String host,int port)，指定要接收的IP地址和端口號(hào)淘寶開(kāi)店
??????? 2）創(chuàng)建服務(wù)端對(duì)象：ServerSocket(int port)：指定接收的客戶(hù)端的端口
??????? 3）Socket accept()：監(jiān)聽(tīng)并接受到此套接字的連接
??????? 4）void shutdownInput()：此套接字的輸入流至于“流的末尾”
??????? 5）void shutdownOutput()：禁用此套接字的輸出流
??????? 6）InputStream getInputStream()：返回此套接字的輸入流，Socket對(duì)象調(diào)用
??????? 7）OutputStream getOutputStream()：返回套接字的輸出流，Socket對(duì)象調(diào)用
3、基本思路
客戶(hù)端：
??????? 1）客戶(hù)端需要明確服務(wù)器的ip地址以及端口，這樣才可以去試著建立連接，如果連接失敗，會(huì)出現(xiàn)異常。
??????? 2）連接成功，說(shuō)明客戶(hù)端與服務(wù)端建立了通道，那么通過(guò)IO流就可以進(jìn)行數(shù)據(jù)的傳輸，而Socket對(duì)象已經(jīng)提供了輸入流和輸出流對(duì)象，通過(guò)getInputStream(),getOutputStream()獲取即可。
??????? 3）與服務(wù)端通訊結(jié)束后，關(guān)閉Socket。
服務(wù)端：
??????? 1）服務(wù)端需要明確它要處理的數(shù)據(jù)是從哪個(gè)端口進(jìn)入的。
??????? 2）當(dāng)有客戶(hù)端訪(fǎng)問(wèn)時(shí)，要明確是哪個(gè)客戶(hù)端，可通過(guò)accept()獲取已連接的客戶(hù)端對(duì)象，并通過(guò)該對(duì)象與客戶(hù)端通過(guò)IO流進(jìn)行數(shù)據(jù)傳輸。
??????? 3）當(dāng)該客戶(hù)端訪(fǎng)問(wèn)結(jié)束，關(guān)閉該客戶(hù)端。
4、步驟
客戶(hù)端：
??????? 通過(guò)查閱Socket對(duì)象的API文檔，發(fā)現(xiàn)在該對(duì)象在建立時(shí)，就可去連接指定主機(jī)，因?yàn)門(mén)CP是面向連接的，所以在建立Socket服務(wù)時(shí)，就要有服務(wù)端存在，并連接成功，形成通路后，再通過(guò)該通道進(jìn)行數(shù)據(jù)的傳輸。
?????????1）創(chuàng)建Socket服務(wù)，并指定要連接的主機(jī)端口。通路一建立，就會(huì)產(chǎn)生Socket流（包括輸入流和輸出流），通過(guò)方法獲取
???????? 2）為了發(fā)送數(shù)據(jù)，應(yīng)獲取Socket中的輸出流，如果要接收服務(wù)端的反饋信息，還需要獲取Socket的輸入流
???????? 3）通過(guò)輸出流的write()方法將要發(fā)送的數(shù)據(jù)寫(xiě)入到流中
???????? 4）關(guān)閉Socket流資源
服務(wù)端：
??????? 服務(wù)器套接字等待請(qǐng)求通過(guò)網(wǎng)絡(luò)傳入。它基于該請(qǐng)求執(zhí)行某些操作，然后可能向請(qǐng)求者返回結(jié)果。需監(jiān)聽(tīng)一個(gè)端口。
?????????1）建立服務(wù)端的Socket服務(wù)，并監(jiān)聽(tīng)一個(gè)端口。通過(guò)ServerSocet帶端口參數(shù)的構(gòu)造函數(shù)
???????? 2）獲取連接過(guò)來(lái)的客戶(hù)對(duì)象，通過(guò)ServerSocket的accept()方法，此方法是阻塞式的，如果服務(wù)端沒(méi)有連接到就會(huì)一直等待
???????? 3）客戶(hù)端如果發(fā)過(guò)來(lái)數(shù)據(jù)，則服務(wù)端要使用對(duì)應(yīng)的客戶(hù)端對(duì)象，并獲取到該客戶(hù)端對(duì)象的讀取流讀取發(fā)過(guò)來(lái)的數(shù)據(jù)，并輸出到指定目的地。
???????? 4）關(guān)閉服務(wù)端（可選）。一般服務(wù)端是常開(kāi)的，因?yàn)樵趯?shí)際應(yīng)用中，隨時(shí)有客戶(hù)端在請(qǐng)求連接和服務(wù)。但這里需要定時(shí)關(guān)閉客戶(hù)端對(duì)象流，避免某一個(gè)客戶(hù)端長(zhǎng)時(shí)間占用服務(wù)器端。
示例：
[java]?view plaincopy
import?java.net.*;??import?java.io.*;??class??TcpClient??{??????public?static?void?main(String[]?args)?throws?Exception??????{??????????????????Socket?s=new?Socket("127.0.0.1",10000);??????????????????OutputStream?out=s.getOutputStream();??????????out.write("你好！".getBytes());??????????????????InputStream?in=s.getInputStream();????????????????????byte[]?buf=new?byte[1024];??????????int?len=in.read(buf);??????????????????System.out.println(new?String(buf,0,len));????????????s.close();????}??}????????class?TcpServer??{??????public?static?void?main(String[]?args)throws?Exception??????{??????????????????ServerSocket?ss=new?ServerSocket(10000);??????????????????Socket?s=ss.accept();??????????????????String?ip=s.getInetAddress().getHostName();??????????System.out.println(ip+"connected....");??????????????????InputStream?in=s.getInputStream();??????????byte[]?buf=new?byte[1024];??????????int?len=in.read(buf);??????????System.out.println(new?String(buf,0,len));????????????????????OutputStream?out=s.getOutputStream();??????????out.write("哥們，收到！".getBytes());????????????????????s.close();??????????ss.close();????}??}?? 練習(xí)一
[java]?view plaincopy
??import?java.io.*;??import?java.net.*;??class??TcpClient??{??????public?static?void?main(String[]?args)?throws?Exception??????{??????????????????Socket?s=new?Socket("127.0.0.1",10000);????????????????????????????BufferedReader?br=new?BufferedReader(new?InputStreamReader(System.in));????????????????????????????????????PrintWriter?pw=new?PrintWriter(s.getOutputStream(),true);????????????????????????????BufferedReader?brin=new?BufferedReader(new?InputStreamReader(s.getInputStream()));????????????String?line=null;??????????while?((line=br.readLine())!=null)??????????{????????????????????????????if("over".equals(line))??????????????????break;????????????????????????????????????????????????????pw.println(line);??????????????String?data=brin.readLine();????????????System.out.println(data);????????????}??????????br.close();????????s.close();??????}??}????class?TcpServer??{??????public?static?void?main(String[]?args)throws?Exception??????{??????????????????ServerSocket?ss?=new?ServerSocket(10000);????????????????????????????Socket?s=ss.accept();????????????????????System.out.println(s.getInetAddress().getHostName()+"?connected.......");????????????????????BufferedReader?brin=new?BufferedReader(new?InputStreamReader(s.getInputStream()));????????????????????????????PrintWriter?pw=new?PrintWriter(s.getOutputStream(),true);????????????String?line=null;??????????while?((line=brin.readLine())!=null)??????????{??????????????System.out.println(line);??????????????????????????????????????????????????????pw.println(line.toUpperCase());????????}??????????s.close();????????ss.close();關(guān)閉資源（可選）??????}??}?? 練習(xí)二
[java]?view plaincopy
??import?java.io.*;??import?java.net.*;??????class??TcpClient??{??????public?static?void?main(String[]?args)?throws?Exception??????{??????????????????Socket?s=new?Socket("127.0.0.1",10000);????????????????????????????BufferedReader?br=new?BufferedReader(new?FileReader("TcpDemo.java"));????????????????????????????PrintWriter?pw=new?PrintWriter(s.getOutputStream(),true);????????????????????BufferedReader?brin=new?BufferedReader(new?InputStreamReader(s.getInputStream()));????????????String?line=null;??????????while?((line=br.readLine())!=null)??????????{??????????????pw.println(line);??????????}????????????????????s.shutdownOutput();??????????System.out.println(brin.readLine());??????????????????br.close();??????????s.close();??????}??}????class?TcpServer??{??????public?static?void?main(String[]?args)throws?Exception??????{??????????????????ServerSocket?ss?=new?ServerSocket(10000);????????????????????????????Socket?s=ss.accept();????????????????????System.out.println(s.getInetAddress().getHostName()+"?connected.......");????????????????????BufferedReader?brin=new?BufferedReader(new?InputStreamReader(s.getInputStream()));????????????????????PrintWriter?out=new?PrintWriter(new?FileWriter("TcpDemo.txt"),true);????????????????????????????BufferedWriter?bwout=new?BufferedWriter(new?OutputStreamWriter(s.getOutputStream()));????????????String?line=null;??????????while?((line=brin.readLine())!=null)??????????{??????????????out.println(line);??????????}??????????????????????????????????????bwout.write("上傳成功!");??????????bwout.newLine();????????bwout.flush();??????????out.close();????????s.close();??????????ss.close();??????}??}?? ?
第三講?????應(yīng)用
一、用TCP客戶(hù)端并發(fā)上傳圖片
1、一對(duì)一（單線(xiàn)程）上傳的思路：
客戶(hù)端
??????? a、服務(wù)端點(diǎn)。
??????? b、讀取客戶(hù)端已有的圖片數(shù)據(jù)
??????? c、通過(guò)Socket輸出流將數(shù)據(jù)發(fā)給服務(wù)端
??????? d、讀取服務(wù)端反饋信息。
??????? e、關(guān)閉
服務(wù)端
?????? ?a、服務(wù)端服務(wù)，并監(jiān)聽(tīng)窗口
??????? b、獲取客戶(hù)端對(duì)象，并獲取客戶(hù)ip
??????? c、讀取客戶(hù)端輸入流數(shù)據(jù)
??????? d、寫(xiě)入文件
??????? e、用客戶(hù)端輸出流反饋信息
??????? f、關(guān)流
2、單線(xiàn)程的服務(wù)端有個(gè)局限性。當(dāng)A客戶(hù)端連接上以后，被服務(wù)端獲取到。服務(wù)端執(zhí)行具體流程。這時(shí)B客戶(hù)端連接，只能等待。因?yàn)榉?wù)端還沒(méi)有處理完A客戶(hù)端的請(qǐng)求。還沒(méi)有循環(huán)回來(lái)執(zhí)行下一次accept方法。所以，暫時(shí)獲取不到B客戶(hù)端對(duì)象。
??????? 那么為了可以讓多個(gè)客戶(hù)端同時(shí)并發(fā)訪(fǎng)問(wèn)服務(wù)端。服務(wù)端最好就是將每個(gè)客戶(hù)端封裝到一個(gè)單獨(dú)的線(xiàn)程中，這樣，就可以同時(shí)處理多個(gè)客戶(hù)端請(qǐng)求。
如何定義線(xiàn)程呢？
??????? 只要明確了每一個(gè)客戶(hù)端要在服務(wù)端執(zhí)行的代碼，將該代碼存入run方法即可。
代碼：
[java]?view plaincopy
??import?java.io.*;??import?java.net.*;??class??PicClient??{??????public?static?void?main(String[]?args)?throws?Exception??????{??????????????????if?(args.length!=1)??????????{??????????????System.out.println("請(qǐng)指定一個(gè)圖片文件！");??????????????return;??????????}????????????File?file=new?File(args[0]);????????????????????if?(!(file.exists()&&file.isFile()))??????????{??????????????System.out.println("你上傳的文件有問(wèn)題，非文件或者不存在！");??????????????return;??????????}????????????????????if?(!file.getName().endsWith(".jpg"))??????????{??????????????System.out.println("圖片格式錯(cuò)誤，請(qǐng)重新選擇！");??????????????return;??????????}????????????????????if?(file.length()>1024*1024*5)??????????{??????????????System.out.println("你上傳的文件過(guò)大,居心叵測(cè)！");??????????????return;??????????}????????????????????Socket?s=new?Socket("localhost",10000);??????????????????FileInputStream?fis=new?FileInputStream(file);????????????????????????????OutputStream?out?=s.getOutputStream();????????????BufferedReader?in=new?BufferedReader(new?InputStreamReader(s.getInputStream()));????????????byte[]?buf=new?byte[1024];????????????int?len=0;????????????while?((len=fis.read(buf))!=-1)??????????{??????????????out.write(buf,0,len);??????????}????????????????????s.shutdownOutput();????????????String?info=in.readLine();????????System.out.println(info);????????????fis.close();????????s.close();????????}??}????class?PicServer??{??????public?static?void?main(String[]?args)throws?Exception??????{??????????????????ServerSocket?ss=new?ServerSocket(10000);????????????????????while?(true)??????????{??????????????????????????Socket?s=ss.accept();??????????????????????????new?Thread(new?PicThread(s)).start();??????????}????????????????????????}??}????class?PicThread?implements?Runnable??{??????private?Socket?s;??????PicThread(Socket?s)??????{??????????this.s=s;??????}??????public?void?run()??????{??????????int?count=1;??????????????????String?ip=s.getInetAddress().getHostAddress();??????????try??????????{?????????????????????System.out.println(ip+"??connected.....");????????????????????????????InputStream?in=s.getInputStream();??????????????????????????File?dir?=new?File("C:\\Users\\asus\\Desktop");??????????????????????????File?file=new?File(dir,ip+".jpg");??????????????????????????while(file.exists())??????????????{??????????????????file=new?File(dir,ip+"("+(count++)+").jpg");??????????????}????????????????????????????FileOutputStream?fos=new?FileOutputStream(file);????????????????byte[]?buf=new?byte[1024];??????????????int?len=0;??????????????while?((len=in.read(buf))!=-1)??????????????{??????????????????fos.write(buf,0,len);??????????????}????????????????????????????OutputStream?out=s.getOutputStream();????????????????????????????out.write("上傳成功！".getBytes());????????????????fos.close();????????????s.close();??????????}??????????catch?(Exception?e)??????????{??????????????throw?new?RuntimeException(ip+"圖片上傳失敗");??????????}??????}??}??
二、客戶(hù)端并發(fā)登錄
????????客戶(hù)端通過(guò)鍵盤(pán)錄入用戶(hù)名，服務(wù)端對(duì)這個(gè)用戶(hù)名進(jìn)行校驗(yàn)。
??????? 如果該用戶(hù)存在，在服務(wù)端顯示xxx，已登陸；并在客戶(hù)端顯示xxx，歡迎光臨。
??????? 如果用戶(hù)不存在，在服務(wù)端顯示xxx，嘗試登陸；并在客戶(hù)端顯示xxx，該用戶(hù)不存在。
??????? 最多就登錄三次。
代碼：?
[java]?view plaincopy
import?java.io.*;??import?java.net.*;??class??LoginClient??{??????public?static?void?main(String[]?args)?throws?Exception??????{??????????????????Socket?s=new?Socket("localhost",10000);??????????????????BufferedReader?br=new?BufferedReader(new?InputStreamReader(System.in));??????????????????????????????PrintWriter?out?=new?PrintWriter(s.getOutputStream(),true?);????????????????????BufferedReader?in=new?BufferedReader(new?InputStreamReader(s.getInputStream()));????????????String?line=null;????????????for(int?x=0;x<3;x++)??????????{??????????????line=br.readLine();????????????if?(line==null)??????????????{??????????????????break;????????????}????????????????out.println(line);??????????????String?info=in.readLine();??????????????System.out.println(info);????????????????if?(info.contains("歡迎"))????????????{??????????????????break;????????????}??????????}????????????br.close();????????s.close();??????}??}????class?LoginServer??{??????public?static?void?main(String?[]?args)throws?Exception??????{??????????????????ServerSocket?ss=new?ServerSocket(10000);????????????????????while?(true)??????????{??????????????????????????Socket?s=ss.accept();????????????????????????????????????new?Thread(new?LoginThread(s)).start();??????????}????????????????????????}??}????class?LoginThread?implements?Runnable??{??????private?Socket?s;??????LoginThread(Socket?s)??????{??????????this.s=s;??????}??????public?void?run()??????{??????????????????String?ip=s.getInetAddress().getHostAddress();??????????System.out.println(ip+"??connected.....");??????????try??????????{?????????????????????for?(int?x=0;x<3?;x++?)??????????????{?????????????????????????????????????BufferedReader?in=new?BufferedReader(new?InputStreamReader(s.getInputStream()));????????????????????????????????????????????????????BufferedReader?br=new?BufferedReader(new?FileReader("users.txt"));????????????????????String?line=in.readLine();????????????????if?(line==null)????????????????{??????????????????????break;????????????????}??????????????????String?data=null;??????????????????boolean?flag=false;????????????????????????????????while?((data=br.readLine())!=null)??????????????????{??????????????????????if?(line.equals(data))??????????????????????{??????????????????????????flag=true;????????????????????????break;??????????????????????}??????????????????}????????????????????????????????????PrintWriter?out=new?PrintWriter(s.getOutputStream(),true);????????????????????if?(flag)??????????????????{??????????????????????System.out.println(line+",已登陸！");????????????????????????????????????????????out.println(line+"，歡迎光臨！");????????????????????????break;????????????????}??????????????????else??????????????????{??????????????????????System.out.println(line+",嘗試登陸！");??????????????????????out.println(line+"，用戶(hù)名不存在！");??????????????????}?????????????????}??????????????s.close();????????}??????????catch?(Exception?e)??????????{??????????????throw?new?RuntimeException("用戶(hù)登陸失敗");??????????}?????????}??}??
三、客戶(hù)端和服務(wù)的瀏覽器演示
??????? 瀏覽器是一個(gè)標(biāo)準(zhǔn)的客戶(hù)端，它可以對(duì)服務(wù)端傳送過(guò)來(lái)的數(shù)據(jù)消息進(jìn)行解析，把符合應(yīng)用層協(xié)議的消息部分解析后，將頭信息拆包掉，傳送到應(yīng)用層，只保留了正確的正文主題部分顯示在主體部分上。
??????? 而由于使用java編譯是在傳輸層和網(wǎng)際層處理的，所以，會(huì)接受到全部的消息，包含了頭消息。而瀏覽器處于應(yīng)用層，已將發(fā)送來(lái)的頭消息去除，只留下了主體信息。
示例：
??????? 自定義服務(wù)器，用瀏覽器訪(fǎng)問(wèn)：
[java]?view plaincopy
import?java.io.*;??import?java.net.*;????class??ServerDemo??{??????public?static?void?main(String[]?args)throws?Exception???????{??????????????????ServerSocket?ss=new?ServerSocket(10000);??????????????????Socket?s=ss.accept();??????????????????String?ip=s.getInetAddress().getHostAddress();????????????System.out.println(ip);??????????????????InputStream?in=s.getInputStream();????????????byte[]?buf=new?byte[1024];??????????int?len=in.read(buf);??????????????????System.out.println(new?String(buf,0,len));??????????????????PrintWriter?out=new?PrintWriter(s.getOutputStream(),true);??????????out.println("<font?color='red'?size='7'>客戶(hù)端你好!</font>");????????????s.close();????????ss.close();??????}??}?? ?
四、URL和URLConnection
1、URL：
??????? URI：范圍更大，條形碼也包含于此范圍
??????? URL：范圍較小，即域名
方法：
??????? 1）構(gòu)造函數(shù)：URL(String protocol,String host,int port,String file);//根據(jù)指定?protocol、host、port號(hào)和?file?創(chuàng)建?URL對(duì)象。
??????? 2）String getProtocol();//獲取協(xié)議名稱(chēng)
??????? 3）String getHost();//獲取主機(jī)名
??????? 4）int getPort();//獲取端口號(hào)
??????? 5）String getFile();//獲取URL文件名
??????? 6）String getPath();//獲取此URL的路徑部分
??????? 7）String getQuery();//獲取此URL的查詢(xún)部，客戶(hù)端傳輸?shù)奶囟ㄐ畔?/p>
注：一般輸入網(wǎng)址，是不帶端口號(hào)的，此時(shí)可進(jìn)行獲取，通過(guò)獲取網(wǎng)址返回的port，若port為-1，則分配一個(gè)默認(rèn)的80端口，如
??????? int port = getPort();
??????? if(port == -1)
????????????? port = 80;
2、URLConnection
方法：
??????? 1）URLConnection openConnection();//用URL調(diào)用此方法，返回一個(gè)?URLConnection?對(duì)象，它表示到?URL?所引用的遠(yuǎn)程對(duì)象的連接。
??????? 2）InputStream getInputStream();//獲取輸入流
??????? 3）OutputStream getOutputStream();//獲取輸出流
示例：
[java]?view plaincopy
??import?java.io.*;??import?java.awt.*;??import?java.awt.event.*;??import?java.net.*;????class?MyIEGUIDemo??{??????????private?Frame?f;??????private?Button?but,bok;??????private?TextField?tf;??????private?TextArea?ta;????????????MyIEGUIDemo()??????{??????????init();??????}????????????public?void?init()??????{??????????????????f=new?Frame("我的Window");??????????but=new?Button("跳轉(zhuǎn)");??????????tf=new?TextField(50);??????????ta=new?TextArea(25,60);????????????????????f.setBounds(300,150,500,500);??????????f.setLayout(new?FlowLayout());????????????????????f.add(tf);??????????f.add(but);??????????f.add(ta);????????????????????myEvent();????????????????????f.setVisible(true);??????}????????????public?void?myEvent()??????{??????????????????f.addWindowListener(new?WindowAdapter()??????????{??????????????public?void?windowClosing(WindowEvent?e)??????????????{??????????????????System.exit(0);??????????????}??????????});????????????????????but.addActionListener(new?ActionListener()??????????{??????????????public?void?actionPerformed(ActionEvent?e)??????????????{??????????????????showFile();????????????}??????????});????????????????????????????????tf.addKeyListener(new?KeyAdapter()??????????{??????????????public?void?keyPressed(KeyEvent?e)??????????????{??????????????????????????????????if(e.getKeyCode()==KeyEvent.VK_ENTER)??????????????????????showFile();??????????????}??????????});??????}????????????????private?void?showFile()??????????{??????????????ta.setText("");??????????????String?path=tf.getText();????????????try??????????????{??????????????????URL?url?=new?URL(path);??連接網(wǎng)頁(yè)服務(wù)器??????????????????URLConnection?conn=url.openConnection();??????????????????????????????????InputStream?in=conn.getInputStream();????????????????????byte[]?buf=new?byte[1024*1024];????????????????????int?len=in.read(buf);??????????????????????????????????ta.append(new?String(buf,0,len));??????????????}??????????????catch?(Exception?e)??????????????{??????????????????throw?new?RuntimeException("連接"+path+"網(wǎng)站失敗");??????????????}??????????}????????public?static?void?main(String[]?args)???????{??????????????????new?MyIEGUIDemo();??????}??}?? ?
小知識(shí)點(diǎn)
1、Socket類(lèi)的構(gòu)造函數(shù)中，有一個(gè)空參數(shù)的構(gòu)造函數(shù)：
??????? Socket()//通過(guò)系統(tǒng)默認(rèn)類(lèi)型的?SocketImpl創(chuàng)建未連接套接字對(duì)象
???????可以通過(guò)connect(SocketAddress endpoint)方法來(lái)連接服務(wù)器。而SocketAddress是一個(gè)抽象類(lèi)，它的子類(lèi)InetSocketAddress實(shí)現(xiàn)了IP套接字地址（IP地址+端口號(hào)）。所以就可以連接到服務(wù)器了。
2、ServerSocket對(duì)象中的構(gòu)造函數(shù)：
??????? ServerSocket(int port,int backlog)，其中的backlog表示隊(duì)列的最大長(zhǎng)度，即最多連入客戶(hù)端的個(gè)數(shù)，即最大連接數(shù)。
3、在瀏覽器輸入網(wǎng)址訪(fǎng)問(wèn)一臺(tái)主機(jī)所做的操作：
???????如輸入http://61.135.169.125，可以直接連接此ip的主機(jī)，而我們一般是輸入主機(jī)名：http:/www.baidu.ocm（百度主機(jī)對(duì)應(yīng)的ip地址就是：61.135.169.125），那么此時(shí)瀏覽器做了神馬操作呢？
?????? 也就是說(shuō)如何通過(guò)主機(jī)名獲取IP地址，從而連接到這臺(tái)主機(jī)呢？這就需要將主機(jī)名翻譯成IP地址，即域名解析：DNS
????????在進(jìn)行訪(fǎng)問(wèn)的時(shí)候，會(huì)先在本地的hosts文件（c:\windows\system32\drivers\ext\host）中找對(duì)應(yīng)的映射。若有，則直接返回請(qǐng)求；若無(wú)，則到公網(wǎng)的映射列表即DNS中找對(duì)應(yīng)的映射，找到后，將主機(jī)名對(duì)應(yīng)的IP地址返回給本機(jī)，本機(jī)通過(guò)這個(gè)IP地址找到對(duì)應(yīng)的服務(wù)器。
示意圖：
?host應(yīng)用：可屏蔽一些惡意網(wǎng)址，即將對(duì)應(yīng)的映射關(guān)系寫(xiě)入hosts中，將IP地址改為本機(jī)的回環(huán)地址，那么會(huì)直接找到hosts，就不會(huì)將請(qǐng)求發(fā)送出去了。
?
轉(zhuǎn)載于:https://www.cnblogs.com/tiankong101/p/4227355.html
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