CS6320:  SW Engineering of Web Based Systems
Instructor Outline Syllabus Projects Links  

 
Important HttpServlet Supporting Classes
About HttpServletRequest and HttpServletResponse
HttpServletRequest
 
  • Represents the client request
  • Use getParameter("name") to get the value of parameter "name" sent in the HTTP request.
  • Use getParameterValues("name") if you think there may be more than one value associated with the parameter "name" sent in the HTTP request.  Will return an array of Strings (this array will be null, or have a length or 1 if there are no or only values for this parameter respectively).
  • Use getParameterNames() to return (as an Enumeration object) the entire set of names of parameters passed via the HTTP request.
  • Use getHeader("headerName")  to revtrieve the value of the HTTP Request Header type "headerName".  About HTTP Request Header types.

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  • Use getHeaderNames() to return (as an Enumeration object) the entire set of names of headers passed via the HTTP request.
  • Use getMethod() to return the request method used (GET, POST, etc.)
  • Use getRequestURI to return the part of the URL that comes after host and port but, before the form data.
  • Use getProtocol to return returns the third part of the request line which is generally HTTP/1.0 or HTTP/1.1 ,etc.
  • Has other rich set of methods...see API.  Example getCookies(), returns an array of any Cookies sent to it in the HTTP Request Header.
HttpServletResponse
 
  • About HTTP Response Header
  • Use to return response to client.
  • Can use methods like getWriter() to retrieve Writer for output to the client.
  • Before sending the created data/document you should do is call method setContentType() to tell the client what kind (e.g. "text/html"), MIME type, of data/document you will be returning.
    • response.setContentType("text/html");
ServletUtilities 
This is a Class created by Author of our "Core Servlets and JSP" book.  See book and corresponding web-site for details and source code you will need to copy and compile!!!!
  • Utility class, number of useful static methods.
  • headWithTitle(String) = static method that takes a string representing a title to an HTML document and constructs using it, the appropriate header HTML tags, returns this as a String.
  • getCookieValue(cookie_array, "name", "default_value") = static method that loops through the array of Cookies,  looking for one who's name matches "name" and will return its value if it exists....if it does not find the cookie, it will return the "default_value" String you specified.
  • getCookie(cookie_array, "name"); = static method that loops through the array of Cookies, looking for one who's name matches "name" and it will return this cookie if it exists.

 
© Lynne Grewe