Java网络编程从入门到精通（30）：定制accept方法

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="ProgId" content="Word.Document"> <meta name="Generator" content="Microsoft Word 11"> <meta name="Originator" content="Microsoft Word 11"> <link rel="File-List" href="file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"> <!--[if gte mso 9]><xml> Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 </xml><![endif]--><!--[if gte mso 9]><![endif]--><style> <!-- /* Font Definitions */ &#64;font-face {font-family:宋体; panose-1:2 1 6 0 3 1 1 1 1 1;} &#64;font-face {font-family:""&#64;宋体"; panose-1:2 1 6 0 3 1 1 1 1 1;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; text-align:justify; text-justify:inter-ideograph; font-size:10.5pt; font-family:"Times New Roman";} /* Page Definitions */ &#64;page {} &#64;page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt;} div.Section1 {page:Section1;} --> </style> <!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable { mso-style-parent:""; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} </style> <![endif]-->

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使用ServerSocket类的implAccept方法可以使用accept方法返回一个Socket子类对象。但implAccept是protected方法，因此，必须在ServerSocket类的子类中覆盖accept方法，然后在accept方法中使用implAccept方法重新设置Socket对象。implAccept方法的定义如下：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->protectedfinalvoidimplAccept(Sockets)throwsIOException

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 11"><meta name="Originator" content="Microsoft Word 11"><link rel="File-List" href="file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><!--[if gte mso 9]><xml> Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 </xml><![endif]--><!--[if gte mso 9]><![endif]--><style> <!-- /* Font Definitions */ &#64;font-face {font-family:宋体; panose-1:2 1 6 0 3 1 1 1 1 1;} &#64;font-face {font-family:""&#64;宋体"; panose-1:2 1 6 0 3 1 1 1 1 1;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; text-align:justify; text-justify:inter-ideograph; font-size:10.5pt; font-family:"Times New Roman";} /* Page Definitions */ &#64;page {} &#64;page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt;} div.Section1 {page:Section1;} --> </style><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable { mso-style-parent:""; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} </style> <![endif]-->

只要通过implAccept方法设置一个未连接的Socket子类对象，accept方法就会返回一个已经连接的Socket子类对象（accept返回的是Socket对象，要想得到Socket子类对象，必须进行类型转换）。在大多数时候不需要改变accept方法的行为，但有时需要一个有更多特性的Socket类。通过implAccept方法就可以达到这个目的。下面的代码定义了一个从Socket继承的HttpSocket类，这个类除了具有Socket类的一切特性外，还增加了一个方法getRequestHeaders，用于返回HTTP请求的头信息。

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->package server;

importjava.net.*;
importjava.io.*;

classHttpSocketextendsSocket
{
publicStringgetRequestHeaders()throwsException
{
InputStreamReaderisr=newInputStreamReader(getInputStream());
BufferedReaderbr=newBufferedReader(isr);
Strings="",result="";
while(!(s=br.readLine()).equals(""))
result=result+s+"\r\n";
returnresult;
}
}

classHttpServerSocketextendsServerSocket
{
publicHttpServerSocket(intport)throwsIOException
{
super(port);
}
publicSocketaccept()throwsIOException//覆盖accept方法
{
Sockets=newHttpSocket();
implAccept(s);//将accept方法返回的对象类型设为HttpSocket
returns;
}
}
publicclassCustomAccept
{
publicstaticvoidmain(String[]args)throwsException
{
HttpServerSockethttpServerSocket=newHttpServerSocket(1234);
HttpSockethttpSocket=(HttpSocket)httpServerSocket.accept();
System.out.println(httpSocket.getRequestHeaders());//向控制台输出HTTP请求头
httpServerSocket.close();
}
}

测试

执行如下命令：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->java server.CustomAccept

在IE的地址栏中输入如下Url：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->http://localhost:1234

CustomAccept在控制台中的运行结果：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->GET/HTTP/1.1
Accept:*/*
Accept-Language:zh-cn
UA-CPU:x86
Accept-Encoding:gzip,deflate
User-Agent:Mozilla/4.0(compatible;MSIE6.0;WindowsNT5.2;SV1;.NETCLR1.1.4322;.NETCLR2.0.50727;InfoPath.1;InfoPath.2)
Host:localhost:1234
Connection:Keep-Alive

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="ProgId" content="Word.Document"> <meta name="Generator" content="Microsoft Word 11"> <meta name="Originator" content="Microsoft Word 11"> <link rel="File-List" href="file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"> <!--[if gte mso 9]><xml> Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 </xml><![endif]--><!--[if gte mso 9]><![endif]--><style> <!-- /* Font Definitions */ &#64;font-face {font-family:宋体; panose-1:2 1 6 0 3 1 1 1 1 1;} &#64;font-face {font-family:""&#64;宋体"; panose-1:2 1 6 0 3 1 1 1 1 1;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; text-align:justify; text-justify:inter-ideograph; font-size:10.5pt; font-family:"Times New Roman";} /* Page Definitions */ &#64;page {} &#64;page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt;} div.Section1 {page:Section1;} --> </style> <!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable { mso-style-parent:""; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} </style> <![endif]-->

上面的运行结果就是IE向服务端发出的HTTP请求头的内容。这个运行结果会根据客户机配置的不同而有所差异。

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