- With help of classes and interfaces available in this package, developing servlets made easy
Interfaces of javax.servlet.http package
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HttpServletRequest
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We read client request data.
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HttpServletResponse
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We write back client response.
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HttpSessionBinding
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Session level data.
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HttpSessionBindingListener
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To link/unlink a object to current session
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Classes of javax.servlet.http package
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HttpServlet
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Provides methods for HTTP Request and Response.
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HttpSessionEvent
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Provides session-changeable events.
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HttpSessionBindingEvent
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Checks if session attribute changed/not.
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Cookie
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Allows to store information at client
side.
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- HttpServletRequest Interface: As name indicates and explained earlier, this interface provides methods to read/get the client data from HTTP Request
Method of HttpServletRequest Interface
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String getRequestedSessionId()
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Provides ID of session
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String getRequestURI()
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Provides URI
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StringBuffer getRequestURL()
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Provides URL
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String getServletPath()
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Provides URL that identifies the
Servlet
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HttpSession getSession()
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Returns Session (If not created, new
session will be created)
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boolean isRequestedSessionIdFromCookie()
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Returns true if session ID is available
in cookie
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boolean isRequestedSessionIdFromURL()
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Returns true if session ID is available
in URL
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boolean isRequestedSessionIdValid()
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Returns true if current context
contains session id.
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String getMethod()
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Provides HTTP Method of request
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- HttpServletResponse Interface: As name indicates and explained earlier, this interface provides methods to write data to client as HTTP Response
Methods of HttpServletResponse Interface
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void sendRedirect(String newUrl)
throws I0Exception
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Redirect the client to provided newUrl.
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void sendError(int
errorcode) throws I0Exception
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Sends error code to client.
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void setStatus(int code)
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Sets status code of this response to code
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void addCookie(Cookie cookie)
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Adds cookie to the HTTP response
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void setHeader(String field, String value)
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Adds relevant field to respective value
to Header
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void setIntHeader(String field, int value)
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Adds relevant field to respective value
to Header
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String encodeURL(String url)
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Decides whether session ID can be
encoded in respective url. If
available, returns modified url
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- HtttpSession Interface: Provides methods to read and write the information related to state of HTTP Session
Methods of HttpSession Interface
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boolean isNew( )
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Returns true if session is not yet accessed by client
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void
removeAttribute(String attr)
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Removes specified attribute from session.
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void setAttribute(String attr, Object val)
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Adds new attribute to session with relevant value.
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String getId( )
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Returns Session Id.
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Enumeration getAttributeNames( )
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Returns an Enum with all list of
Attributes
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Object getAttribute(String attr)
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For given attribute, returns its value
in session.
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long getCreationTime( )
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Returns times since session is created (in milliseconds)
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- HttpSessionBindingListener Interface: This need to implemented by a objects that need to be send a word when they are bound or unbound from HTTP Session
Methods of HttpSessionBindingListener
Interface
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void
valueBound(HttpSessionBindingEvent e)
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To bound with event e that describes binding.
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void valueUnbound(HttpSessionBindingEvent e)
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To unbound with event e that describes binding.
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