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|How do I use a scriptlet to initialize a newly instantiated bean?|
A jsp:useBean action may optionally have a body. If the body is specified, its contents will be automatically invoked when the specified bean is instantiated. Typically, the body will contain scriptlets or jsp:setProperty tags to initialize the newly instantiated bean, although you are not restricted to using those alone.
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|What is a output comment?|
A comment that is sent to the client in the viewable page source. The JSP engine handles an output comment as uninterrupted HTML text, returning the
|What is a Hidden Comment?|
A Comments that documents the JSP page but is not sent to the client. The JSP engine ignores a hidden comment, and does not process any code within hidden comment tags. A hidden comment is not sent to the client, either in the displayed JSP page or the HTML page source.
The hidden comment is useful when you want to hide or comment out part of your JSP page. You can use any characters in the body of the comment except the closing --%> combination. If you need to use --%> in your comment, you can escape it by typing --%>.
JSP Syntax :
<%-- comment --%> Examples <%@ page language="java" %>
A Hidden Comment
<%-- This comment will not be visible to the colent in the page source --%>
|What is a Expression?|
An expression tag contains a scripting language expression that is evaluated, converted to a String, and inserted where the expression appears in the JSP file. Because the value of an expression is converted to a String, you can use an expression within text in a JSP file. Like
|What is a Declaration?|
A declaration declares one or more variables or methods for use later in the JSP source file.
|What is a Scriptlet?|
A scriptlet can contain any number of language statements, variable or method declarations, or expressions that are valid in the page scripting language.Within scriptlet tags, you can
|What are implicit objects? List them?|
Certain objects that are available for the use in JSP documents without being declared first. These objects are parsed by the JSP engine and inserted into the generated servlet. The implicit objects re listed below
|Difference between forward and sendRedirect?|
When you invoke a forward request, the request is sent to another resource on the server, without the client being informed that a different resource is going to process the request. This process occurs completly with in the web container.
When a sendRedirtect method is invoked, it causes the web container to return to the browser indicating that a new URL should be requested. Because the browser issues a completly new request any object that are stored as request attributes before the redirect occurs will be lost. This extra round trip a redirect is slower than forward.
|What are the different scope valiues for the |
The different scope values for <jsp:useBean> are
|Explain the life-cycle mehtods in JSP?|
The generated servlet class for a JSP page implements the HttpJspPage interface of the javax.servlet.jsp package. HttpJspPage interface extends the JspPage interface which inturn extends the Servlet interface of the javax.servlet package. the generated servlet class thus implements all the methods of the these three interfaces. The JspPage interface declares only two mehtods - jspInit() and jspDestroy() that must be implemented by all JSP pages regardless of the client-server protocol. However the JSP specification has provided the HttpJspPage interfaec specifically for the JSp pages serving HTTP requests. This interface declares one method _jspService().
|How do I prevent the output of my JSP or Servlet pages from being cached by the browser?|
You will need to set the appropriate HTTP header attributes to prevent the dynamic content output by the JSP page from being cached by the browser. Just execute the following scriptlet at the beginning of your JSP pages to prevent them from being cached at the browser. You need both the statements to take care of some of the older browser versions.
<% response.setHeader("Cache-Control","no-store"); //HTTP 1.1
response.setHeader("Pragma","no-cache"'); //HTTP 1.0
response.setDateHeader ("Expires", 0); //prevents caching at the proxy server
|How does JSP handle run-time exceptions?|
You can use the errorPage attribute of the page directive to have uncaught run-time exceptions automatically forwarded to an error processing page. For example: <%@ page errorPage='error.jsp' %> redirects the browser to the JSP page error.jsp if an uncaught exception is encountered during request processing. Within error.jsp, if you indicate that it is an error-processing page, via the directive: <%@ page isErrorPage='true' %> Throwable object describing the exception may be accessed within the error page via the exception implicit object. Note: You must always use a relative URL as the value for the errorPage attribute.
|How can I implement a thread-safe JSP page? What are the advantages and Disadvantages of using it?|
You can make your JSPs thread-safe by having them implement the SingleThreadModel interface. This is done by adding the directive <%@ page isThreadSafe='false' %> within your JSP page. With this, instead of a single instance of the servlet generated for your JSP page loaded in memory, you will have N instances of the servlet loaded and initialized, with the service method of each instance effectively synchronized. You can typically control the number of instances (N) that are instantiated for all servlets implementing SingleThreadModel through the admin screen for your JSP engine. More importantly, avoid using the tag for variables. If you do use this tag, then you should set isThreadSafe to true, as mentioned above. Otherwise, all requests to that page will access those variables, causing a nasty race condition. SingleThreadModel is not recommended for normal use. There are many pitfalls, including the example above of not being able to use <%! %>. You should try really hard to make them thread-safe the old fashioned way: by making them thread-safe .
|What's a better approach for enabling thread-safe servlets and JSPs? SingleThreadModel Interface or Synchronization?|
|Although the SingleThreadModel technique is easy to use, and works well for low volume sites, it does not scale well. If you anticipate your users to increase in the future, you may be better off implementing explicit synchronization for your shared data. The key however, is to effectively minimize the amount of code that is synchronzied so that you take maximum advantage of multithreading. Also, note that SingleThreadModel is pretty resource intensive from the server's perspective. The most serious issue however is when the number of concurrent requests exhaust the servlet instance pool. In that case, all the unserviced requests are queued until something becomes free - which results in poor performance. Since the usage is non-deterministic, it may not help much even if you did add more memory and increased the size of the instance pool.|
|How can I enable session tracking for JSP pages if the browser has disabled cookies?|
|What is the difference b/w variable declared inside a declaration part and variable declared in scriplet part?|
|Variable declared inside declaration part is treated as a global variable.that means after convertion jsp file into servlet that variable will be in outside of service method or it will be declared as instance variable.And the scope is available to complete jsp and to complete in the converted servlet class.where as if u declare a variable inside a scriplet that variable will be declared inside a service method and the scope is with in the service method.|
|Pipes and Cistern|
Three taps A,B and C can fill a tank in 12, 15 and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternatively, the tank will be full in?
Two pipes A and B can fill a tank in 6 hours and 4 hours respectively. If they are opened on alternate hours and if pipe A s opened first, in how many hours, the tank shall be full?
A large tanker can be filled by two pipes A and B in 60 min and 40 min respectively. How many minutes will it take to fill the tanker from empty state if B is used for first half of the time, and A and B fill it together for the other half?
A tank is filled by 3 pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same time during which the tank is filled by the third pipe alone. The 2nd pipe fills the tank 5 hours faster than first pipe and 4 hours slower than third pipe. The time required by first pipe is?
Two pipes A and B together can fill a cistern in 4 hours. Had they been opened separately, then B would have taken 6 hours more than A to fill the cistern. How much time will be taken by A to fill the cistern separately?
Two pipes A and B can fill a tank in 24 min and 32 min respectively. If both the pipes are opened simultaneously, after how much time B should be closed so that the tank is full in 18 min?
Two pipes A and B can fill a tank in 36 min and 45 min respectively. A water pipe C can empty the tank in 30 min. First A and B are opened. after 7 min, C is also opened. In how much time, the tank is full?
Two pipes can fill a cistern in 14 hours and 16 hours respectively. The pipes are opened simultaneously and it is found that due to leakage in the bottom it took 32 min more to fill the cistern. When the cistern is full, in what time will the leak empty it?
Bucket P has thrice the capacity as Bucket Q. It takes 60 turns for Bucket P to fill the empty drum. How many turns it will take for both the buckets P and Q, having each turn together to fill the empty drum?
In a class , 30 % of the students offered English, 20 % offered Hindi and 10 % offered Both.If a student is offered at random, what is the probability that he has offered English or Hindi?
In a lottery ,there are 10 prizes and 25 blanks.A lottery is drawn at random. what is the probability of getting a prize ?
Two dice are thrown simultaneously .what is the probability of getting two numbers whose product is even?
Two diced are tossed the probability that the total score is a prime number?
Two cards are drawn at random from a pack of 52 cards What is the probability that either both are black or both are queens?
Two dice are thrown together .What is the probability that the sum of the number on the two faces is divisible by 4 or 6?
A bag contains 6 white and 4 black balls .Two balls are drawn at random .Find the probability that they are of the same colour?
In a simultaneous throw of a pair of dice,find the probability of getting a total more than 7?
An unbiased die is tossed.Find the probability of getting a multiple of 3?
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कर्मचारी चयन आयोग (एसएससी) Staff Selection Commission (SSC) - 1411 पद - 29/07/2022 अंतिम तिथि
|Jobs in Rajasthan|
राजस्थान अधीनस्थ और मंत्रिस्तरीय सेवा चयन बोर्ड Rajasthan Subordinate and Ministerial Services Selection Board (RSMSSB) - 5546 पद - 22-Jul-2022 अंतिम तिथि
उत्तर मध्य रेलवे भर्ती प्रकोष्ठ Railway Recruitment Cell(NCR) - 1659 पद - 01/08/2022 अंतिम तिथि
|Jobs in West Bengal|
इंडियन पोस्ट सर्विस Indian Post Service - 2357 पद - 19/08/2021 अंतिम तिथि - पश्चिम बंगाल पोस्टल सर्कल
भारतीय स्टेट बैंक State Bank of India(SBI) - 6100 पद - 26/07/2021 अंतिम तिथि - CRPD/APPR/2021-22/10
कर्मचारी चयन आयोग Staff Selection Commission(SSC) - 25271 पद - 31/08/2021 अंतिम तिथि
|Jobs in Madhya Pradesh|
राष्ट्रीय स्वास्थ्य मिशन मध्य प्रदेश National Health Mission MP(NRHM) - 5215 पद - 22/06/2021 अंतिम तिथि
|Jobs in Punjab|
पंजाब स्टेट पावर कॉर्पोरेशन लिमिटेड Punjab State Power Corporation Limited (PSPCL) - 2632 पद - 20/06/2021 अंतिम तिथि
|Jobs in Chhattisgarh|
स्वास्थ्य सेवा निदेशालय, छत्तीसगढ़ Department of Health & Family Welfare, Chhattisgarh - 267 पद - 26/06/2021 अंतिम तिथि