📄 05-套接字编程（下2）.htm
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<TD>Listing 4: DGSClient.java<BR>// DGSClient.java<BR><BR>import java.io.*;<BR>import java.net.*;<BR><BR>class DGSClient<BR>{<BR> public static void main (String [] args)<BR> {<BR> String host = "localhost";<BR><BR> // If user specifies a command-line argument, that argument<BR> // represents the host name.<BR> <BR> if (args.length == 1)<BR> host = args [0];<BR><BR> DatagramSocket s = null;<BR><BR> try<BR> {<BR> // Create a datagram socket bound to an arbitrary port.<BR><BR> s = new DatagramSocket ();<BR><BR> // Create a byte array that will hold the data portion of a<BR> // datagram packet's message. That message originates as a<BR> // String object, which gets converted to a sequence of<BR> // bytes when String's getBytes() method is called. The<BR> // conversion uses the platform's default character set.<BR><BR> byte [] buffer;<BR> buffer = new String ("Send me a datagram").getBytes ();<BR><BR> // Convert the name of the host to an InetAddress object.<BR> // That object contains the IP address of the host and is<BR> // used by DatagramPacket.<BR><BR> InetAddress ia = InetAddress.getByName (host);<BR><BR> // Create a DatagramPacket object that encapsulates a<BR> // reference to the byte array and destination address<BR> // information. The destination address consists of the<BR> // host's IP address (as stored in the InetAddress object)<BR> // and port number 10000 -- the port on which the server<BR> // program listens.<BR><BR> DatagramPacket dgp = new DatagramPacket (buffer,<BR> buffer.length,<BR> ia,<BR> 10000);<BR><BR> // Send the datagram packet over the socket.<BR><BR> s.send (dgp);<BR><BR> // Create a byte array to hold the response from the server.<BR> // program.<BR><BR> byte [] buffer2 = new byte [100];<BR><BR> // Create a DatagramPacket object that specifies a buffer<BR> // to hold the server program's response, the IP address of<BR> // the server program's computer, and port number 10000.<BR><BR> dgp = new DatagramPacket (buffer2,<BR> buffer.length,<BR> ia,<BR> 10000);<BR><BR> // Receive a datagram packet over the socket.<BR><BR> s.receive (dgp);<BR><BR> // Print the data returned from the server program and stored<BR> // in the datagram packet.<BR><BR> System.out.println (new String (dgp.getData ()));<BR><BR> }<BR> catch (IOException e)<BR> {<BR> System.out.println (e.toString ());<BR> }<BR> finally<BR> {<BR> if (s != null)<BR> s.close (); <BR> }<BR> }<BR>} </TD></TR></TBODY></TABLE><BR> DGSClient由创建一个绑定任意本地（客户端）端口好的DatagramSocket对象开始，然后装入带有文本信息的数组buffer和描述服务器主机IP地址的InetAddress子类对象的引用，接下来，DGSClient创建了一个DatagramPacket对象，该对象加入了带文本信息的缓冲器的引用，InetAddress子类对象的引用，以及服务端口号10000, DatagramPacket的自寻址数据包通过方法sent()发送给服务器程序，于是一个包含服务程序响应的新的DatagramPacket对象被创建，receive()得到响应的自寻址数据包，然后自寻址数据包的getData()方法返回该自寻址数据包的一个引用，最后关闭DatagramSocket。<BR><BR> DGSServer服务程序补充了DGSClient的不足，List5是DGSServer的源代码：<BR><BR>
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<TD>Listing 5: DGSServer.java<BR>// DGSServer.java<BR><BR>import java.io.*;<BR>import java.net.*;<BR><BR>class DGSServer<BR>{<BR> public static void main (String [] args) throws IOException<BR> {<BR> System.out.println ("Server starting ...\n");<BR><BR> // Create a datagram socket bound to port 10000. Datagram<BR> // packets sent from client programs arrive at this port.<BR><BR> DatagramSocket s = new DatagramSocket (10000);<BR><BR> // Create a byte array to hold data contents of datagram<BR> // packet.<BR><BR> byte [] data = new byte [100];<BR><BR> // Create a DatagramPacket object that encapsulates a reference<BR> // to the byte array and destination address information. The<BR> // DatagramPacket object is not initialized to an address <BR> // because it obtains that address from the client program.<BR><BR> DatagramPacket dgp = new DatagramPacket (data, data.length);<BR><BR> // Enter an infinite loop. Press Ctrl+C to terminate program.<BR><BR> while (true)<BR> {<BR> // Receive a datagram packet from the client program.<BR><BR> s.receive (dgp);<BR><BR> // Display contents of datagram packet.<BR><BR> System.out.println (new String (data));<BR><BR> // Echo datagram packet back to client program.<BR><BR> s.send (dgp);<BR> }<BR>}<BR>}</TD></TR></TBODY></TABLE><BR> DGSServer创建了一个绑定端口10000的自寻址套接字，然后创建一个字节数组容纳自寻址信息，并创建自寻址包，下一步，DGSServer进入一个无限循环中以接收自寻址数据包、显示内容并将响应返回客户端，自寻址套接没有关闭，因为循环是无限的。<BR><BR> 在编译DGSServer 和DGSClient的源代码后，由输入java DGSServer开始运行DGSServer，然后在同一主机上输入Java DGSClient开始运行DGSClient，如果DGSServer与DGSClient运行于不同主机，在输入时注意要在命令行加上服务程序的主机名或IP地址，如：java DGSClient <A href="http://www.yesky.com">www.yesky.com</A><br><br> </DIV> </TD> </TR> <TR> <TD class=center01> <div align="center">来源：天极网 作者：<div> </TD> <TD width="280" class=center01> <div align="center"> <font color=#0000FF><a href='chapter.php?id=387&volume=3&chapter=4'>上一页</a></font> <font color=#0000FF><a href="serialize.php?id=387">回书目</a></font> <font color=#0000FF><a href='chapter.php?id=387&volume=3&chapter=6'>下一页</a></font> </div> </TD> </TR> </TBODY></TABLE><table><tr><td width="760"> <table width="760" height="10" border="0" cellpadding="0" cellspacing="0"> <tr> <td></td> </tr> </table> <!------------ 评论 ----------------> <table width="760" border="0" cellpadding="0" cellspacing="0"> <tr> <td><iframe width="100%" id=vs frameborder=0 scrolling=no src="comment_list1.php?id=387"></iframe> </td> </tr> </table><br><script language=javascript>function CheckNetwordForm(theForm){ if("" == theForm.content.value) { alert("写两句吧~~"); theForm.content.focus(); return false; } var index; for(index=0;index<theForm.content.value.length;index++) { if(" " != theForm.content.value.charAt(index)) break; } if(index == theForm.content.value.length) { alert("写两句吧~~"); theForm.content.focus(); return false; } if (theForm.content.value.length>100){ alert("评论字数不能超过100哦"); theForm.content.focus(); return false; } return true;}</script> <!------------------ 评论 ---------------> <form name=netword method=post action="insertnetword.php" onsubmit="javascript: return CheckNetwordForm(this);"> <table width="760" border="0" cellpadding="0" cellspacing="0"> <tr> <td height="25" class="text6"> 给此书打分：<a name="1"></a> <select name="score"> <option value=5 selected>非常好</option> <option value=4>还凑合</option> <option value=3>一般吧</option> <option value=2>不太行</option> <option value=1>太差了</option> </select> 用户名： <input name="id" value=387 type="hidden" id="id"> <input name="backurl" value=/book/chapter.php?id=387&volume=3&chapter=5 type="hidden"> <input name="username" type="text" id="username" size="20" maxlength="20"> <font color="#666666">*评论字数请控制在一百字以内</font> </td> </tr> </table> <br> <textarea name="content" cols="80" rows="4" wrap="OFF" id="description"></textarea> <input type="submit" name="Submit" value="提交"> </form> </td> </tr></table></td></tr></table> <TABLE cellSpacing=0 cellPadding=0 width=760 border=0> <TBODY> <TR> <TD width="1003" height=9 background=images/t_bj01.gif><IMG height=1 src="images/ccc.gif" width=1></TD> </TR> </TBODY></TABLE><TABLE cellSpacing=0 cellPadding=0 width=760 bgColor=#ffffff border=0> <TBODY> <TR> <TD><HR width=760 noShade SIZE=1> </TD> </TR> <TR> <TD align=middle><A class=black href="http://www.chinaren.com/" target=_blank>ChinaRen</A> - <A class=black href="http://big5.www.sohu.com/" target=_blank>繁体版</A> - <A class=black href="http://hr.sohu.com/hrm.html" target=_blank>搜狐招聘</A> - <A class=black href="http://add.sohu.com/" target=_blank>网站登录</A> - <A class=black href="http://help.sohu.com/" target=_blank>帮助中心</A> - <A class=black href="http://book.news.sohu.com/onClick=this.style.behavior='url(#default#homepage)';this.setHomePage('http://www.sohu.com');return" target=_blank false;>设置首页</A> - <A class=black href="http://adinfo.sohu.com/" target=_blank>广告服务</A> - <A class=black href="http://www.sohu.com/about/lianxi.htm" target=_blank>联系方式</A> - <A class=black href="http://www.sohu.com/about/privacy.html" target=_blank>保护隐私权</A> - <A class=black href="http://www.sohu.com/about/" target=_blank>About SOHU</A> - <A class=black href="http://www.sohu.com/about/" target=_blank>公司介绍</A><BR> <SPAN class=eng>Copyright © 2004 Sohu.com Inc. 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