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Appendix A

Servlet and JSP Quick Reference

  Cookie: cookies sent to client by server sometime earlier. Use 

getCookies

, not 

getHeader

. See Chapter 8.

  Host: host given in original URL. This is a required header in HTTP 

1.1.

  If Modified Since: indicates client wants page only if it has been 

changed after specified date. Don't handle this situation directly; 

implement 

getLastModified

 instead. See example in Section 2.8.

  Referer: URL of referring Web page.

  User Agent: string identifying the browser making the request.

A.5 Accessing the Standard CGI Variables

You should usually think in terms of request info, response info, and server

info, not CGI variables.

Capabilities Not Discussed Elsewhere

  getServletContext().getRealPath("uri"): maps URI to real path 

  request.getRemoteHost(): name of host making request

  request.getRemoteAddress(): IP address of host making request

Servlet Equivalent of CGI Variables

  AUTH_TYPE: 

request.getAuthType()

  CONTENT_LENGTH: 

request.getContentLength()

  CONTENT_TYPE: 

request.getContentType()

  DOCUMENT_ROOT: 

getServletContext().getRealPath("/")

  HTTP_XXX_YYY: 

request.getHeader("Xxx Yyy")

  PATH_INFO: 

request.getPathInfo()

  PATH_TRANSLATED: 

request.getPathTranslated()

  QUERY_STRING: 

request.getQueryString()

  REMOTE_ADDR: 

request.getRemoteAddr()

  REMOTE_HOST: 

request.getRemoteHost()

  REMOTE_USER: 

request.getRemoteUser()

  REQUEST_METHOD: 

request.getMethod()

  SCRIPT_NAME: 

request.getServletPath()

  SERVER_NAME: 

request.getServerName()

  SERVER_PORT: 

request.getServerPort()

  SERVER_PROTOCOL: 

request.getProtocol()

  SERVER_SOFTWARE: 

getServletContext().getServerInfo()

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

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