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六、访问CGI变量_MySQL

Jun 01, 2016 pm 02:07 PM
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6.1 CGI变量概述

   如果你是从传统的CGI编程转而学习Java Servlet,或许已经习惯了“CGI变量”这一概念。CGI变量汇集了各种有关请求的信息:

部分来自HTTP请求命令和请求头,例如Content-Length头;
部分来自Socket本身,例如主机的名字和IP地址;
也有部分与服务器安装配置有关,例如URL到实际路径的映射。
   6.2 标准CGI变量的Servlet等价表示

   下表假定request对象是提供给doGet和doPost方法的HttpServletRequest类型对象。 CGI变量  含义  从doGet或doPost访问  
AUTH_TYPE  如果提供了Authorization头,这里指定了具体的模式(basic或者digest)。  request.getAuthType()  
CONTENT_LENGTH  只用于POST请求,表示所发送数据的字节数。  严格地讲,等价的表达方式应该是String.valueOf(request.getContentLength())(返回一个字符串)。但更常见的是用request.getContentLength()返回含义相同的整数。  

CONTENT_TYPE  如果指定的话,表示后面所跟数据的类型。  request.getContentType()  
DOCUMENT_ROOT  与http://host/对应的路径。  getServletContext().getRealPath("/")
注意低版本Servlet规范中的等价表达方式是request.getRealPath("/")。

HTTP_XXX_YYY  访问任意HTTP头。  request.getHeader("Xxx-Yyy")  
PATH_INFO  URL中的附加路径信息,即URL中Servlet路径之后、查询字符串之前的那部分。  request.getPathInfo()  
PATH_TRANSLATED  映射到服务器实际路径之后的路径信息。  request.getPathTranslated()  
QUERY_STRING  这是字符串形式的附加到URL后面的查询字符串,数据仍旧是URL编码的。在Servlet中很少需要用到未经解码的数据,一般使用getParameter访问各个参数。  request.getQueryString()  
REMOTE_ADDR  发出请求的客户机的IP地址。  request.getRemoteAddr()  
REMOTE_HOST  发出请求的客户机的完整的域名,如java.sun.com。如果不能确定该域名,则返回IP地址。  request.getRemoteHost()  
REMOTE_USER  如果提供了Authorization头,则代表其用户部分。它代表发出请求的用户的名字。  request.getRemoteUser()  
REQUEST_METHOD  请求类型。通常是GET或者POST。但偶尔也会出现HEAD,PUT, DELETE,OPTIONS,或者 TRACE.  request.getMethod()  
SCRIPT_NAME  URL中调用Servlet的那一部分,不包含附加路径信息和查询字符串。  request.getServletPath()  
SERVER_NAME  Web服务器名字。  request.getServerName()  

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