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Features of Servlets 2.4

In this tutorial you will learn the new features added in Servlet 2.4.

Features of Servlets 2.4


In this tutorial you will learn the new features added in Servlet 2.4.

  1. Upgraded supports for Http, J2SE, and J2EE: Servlet 2.4 depends on Http1.1 and J2SE 1.3.
  2. Additional ServletRequest methods : In Servlet 2.4 four new methods are added in the ServletRequest
    • getRemotePort(): It returns the IP source port of the client.
    • getLocalName(): It returns the host name on which the request was recieved.
    • getLocalAddr(): It returns the IP address on which the request was recieved. 
    • getLocalPort(): It returns the IP port number.
  3. New Support for Internationalization and charset choice: To provide support of internationization, Servlet 2.4 has added two new methods in the ServletResponse interface.
    • setCharacterEncoding(String encoding): The purpose of this method is to set the response's character encoding.  This method helps us to pass a charset parameter to setContentType(String) or passing a Locale to setLocale(Locale). We can now avoid setting the charset in the setContentType("text/html;charset=UTF-8") as setCharacterEncoding() method pairs with the pre-existing getCharacterEncoding() method to manipulate and view the response's character encoding.
    • getContentType(): It is responsible for returning the response's content type. The content type can be dynamically set with a combination of setContentType(), setLocale(), and setCharacterEncoding() calls, and the method getContentType() provides a way to view the generated type string. 
  4. New features has been added in RequestDispatcher: In Servlet 2.4 five new request attributes has been added for providing extra information during a RequestDispatcher forward() call. This features has been added is Servlet 2.4 to know the true original request URI. The following request attributes are:
    • javax.servlet.forward.request_uri
    • javax.servlet.forward.context_path
    • javax.servlet.forward.servlet_path
    • javax.servlet.forward.path_info
    • javax.servlet.forward.query_string

  5. SingleThreadModel interface has been deprecated: In Servlet 2.4 the SingleThreadModel interface has been deprecated. 
  6. HttpSession details and interaction with logins has been clarified: The new method HttpSession.logout() has been added in Servlet 2.4. Now session allows zero or negative values in the <session-timeout> element to indicate sessions should never time out. 
    If the object in the session can't be serialize in a distributed environment then it must throw an IllegalArgumentException. 
  7. Welcome file behavior and Classloading has been clarified: In servlet 2.4 welcome file can be a servlet. 
  8. The web.xml file now uses XML Schema: Version 2.4 servers must still accept the 2.2 and 2.3 deployment descriptor formats, but all new elements are solely specified in Schema.



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June 16, 2011

This website is very useful for me to learn java,j2ee