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Java Articles
Page 417 of 450
How can we maintain session between Web Client and Web Server?
Following are the few options to maintain the session between the Web Client and the Web Server −CookiesA webserver can assign a unique session ID as a cookie to each web client and for subsequent requests from the client they can be recognized using the received cookie.This may not be an effective way as the browser at times does not support a cookie. It is not recommended to use this procedure to maintain the sessions.Hidden Form FieldsA web server can send a hidden HTML form field along with a unique session ID as follows −This entry means that, when the ...
Read MoreWhich methods can be used to read HTTP header in your JSP program.
The request object provides methods to get HTTP header information including form data, cookies, HTTP methods, etc.Following table lists out the important methods that can be used to read HTTP header in your JSP program. These methods are available with HttpServletRequest object which represents client request to webserver.Sr.No.Method & Description1Cookie[] getCookies()Returns an array containing all of the Cookie objects the client sent with this request.2Enumeration getAttributeNames()Returns an Enumeration containing the names of the attributes available to this request.3Enumeration getHeaderNames()Returns an enumeration of all the header names this request contains.4Enumeration getParameterNames()Returns an enumeration of String objects containing the names of the ...
Read MoreWhat methods of session object is used frequently in JSP and for what purpose?
Here is a summary of important methods available through the session object −Sr.No.Method & Description1public Object getAttribute(String name)This method returns the object bound with the specified name in this session, or null if no object is bound under the name.2public Enumeration getAttributeNames()This method returns an Enumeration of String objects containing the names of all the objects bound to this session.3public long getCreationTime()This method returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT.4public String getId()This method returns a string containing the unique identifier assigned to this session.5public long getLastAccessedTime()This method returns the last ...
Read MoreHow to delete Session data in JSP?
When you are done with a user's session data, you have several options −Remove a particular attribute − You can call the public void removeAttribute(String name) method to delete the value associated with the particular key.Delete the whole session − You can call the public void invalidate() method to discard an entire session.Setting Session timeout − You can call the public void setMaxInactiveInterval(int interval) method to set the timeout for a session individually.Log the user out − The servers that support servlets 2.4, you can call logout to log the client out of the Web server and invalidate all sessions ...
Read MorePlease share a working example of session maintenance in JSP.
This example describes how to use the HttpSession object to find out the creation time and the last-accessed time for a session. We would associate a new session with the request if one does not already exist. Session Tracking Session Tracking Session info Value ...
Read MoreWhat is a config Object in JSP?
The config object is an instantiation of javax.servlet.ServletConfig and is a direct wrapper around the ServletConfig object for the generated servlet.This object allows the JSP programmer access to the Servlet or JSP engine initialization parameters such as the paths or file locations etc.The following config method is the only one you might ever use, and its usage is trivial −config.getServletName();This returns the servlet name, which is the string contained in the element defined in the WEB-INF\web.xml file.
Read MoreWhat is a pageContext Object in JSP?
The pageContext object is an instance of a javax.servlet.jsp.PageContext object. The pageContext object is used to represent the entire JSP page.This object is intended as a means to access information about the page while avoiding most of the implementation details.This object stores references to the request and response objects for each request. The application, config, session, and out objects are derived by accessing attributes of this object.The pageContext object also contains information about the directives issued to the JSP page, including the buffering information, the errorPageURL, and page scope.The PageContext class defines several fields, including PAGE_SCOPE, REQUEST_SCOPE, SESSION_SCOPE, and APPLICATION_SCOPE, ...
Read MoreWhat is the use of page object in JSP? Need an example.
JSP gives you an option to specify Error Page for each JSP using page attribute. Whenever the page throws an exception, the JSP container automatically invokes the error page.Following is an example to specifiy an error page for a main.jsp. To set up an error page, use the directive. Error Handling Example We will now write one Error Handling JSP ShowError.jsp, which is given below. Notice that the error-handling page includes the directive . This directive causes ...
Read MoreHow to create a common error page using JSP?
JSP gives you an option to specify Error Page for each JSP using page attribute. Whenever the page throws an exception, the JSP container automatically invokes the error page.Following is an example to specifiy an error page for a main.jsp. To set up an error page, use the directive. Error Handling Example We will now write one Error Handling JSP ShowError.jsp, which is given below. Notice that the error-handling page includes the directive . This directive causes the JSP compiler ...
Read MoreHow to handle error object in JSP using JSTL tags?
You can make use of JSTL tags to write an error page ShowError.jsp with better structure and more information − Show Error Page Opps... Error: ${pageContext.exception} URI: ${pageContext.errorData.requestURI} ...
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