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Table of Contents
                            Core
Classloader
Classloader is a subsystem of JVM that is used to load class files
	
1. BootStrap ClassLoader
2. Extension ClassLoader
3. SystemClassLoader
Bootstrap class loader loads all java core classes, which are at the part of runtime. Bootstrap ClassLoader - JRE/lib/rt.jar
Extension ClassLoader - JRE/lib/ext or any directory denoted by java.ext.dirs
Application ClassLoader - CLASSPATH environment variable, -classpath or -cp option, Class-Path attribute of Manifest inside JAR file.
	Aggregation
	o    If a class have an entity reference, it is known as Aggregation. Aggregation represents HAS-A relationship.
	o    We are passing object instance from outside in Aggregation.
		Uses
	o    For Code Reusability
	o    Inheritance should be used only if the relationship is-a is maintained throughout the lifetime of the objects involved; otherwise, aggregation is the best choice
		Address.java
	
	
	
		Emp.java
	
	
	Composition
	o    Composition is the design technique to implement has-a relationship in classes. We can use java inheritance or Object composition for code reuse.
	o    We are creating object instance from inside in Composition.
		Address.java

	
		Emp.java
	
	
	String, StringBuffer and StringBuilder
		String
	String is immutable in Java. Immutability offers lot of benefit to the String hashcode value can be cached which makes it a faster hashmap key and one of the reasons why String is a popular key in HashMap. Because String is final it can be safely shared between multiple threads without any extra synchronization.
		StringBuffer
	StringBuffer is very good with mutable String but it has one disadvantage all its public methods are synchronized which makes it thread-safe but same time slow.
		StringBuilder
	In JDK 5 they provided similar class called StringBuilder in Java which is a copy of StringBuffer but without synchronization. Try to use StringBuilder whenever possible it performs better in most of cases than StringBuffer class.
		JSP
	1.What are the advantages of JSP over Servlet?
	JSP is a serverside technology to make content generation a simple appear.The advantage of JSP is that they are document-centric. Servlets, on the other hand, look and act like programs. A Java Server Page can contain Java program fragments that instantiate and execute Java classes, but these occur inside an HTML template file and are primarily used to generate dynamic content. Some of the JSP functionality can be achieved on the client, using JavaScript. The power of JSP is that it is server-based and provides a framework for Web application development.
	2.What is the life-cycle of JSP?
	When a request is mapped to a JSP page for the first time, it translates the JSP page into a servlet class and compiles the class. It is this servlet that services the client requests.
	A JSP page has seven phases in its lifecycle, as listed below in the sequence of occurrence:
Translation
Compilation
Loading the class
Instantiating the class
jspInit() invocation
_jspService() invocation
jspDestroy() invocation
3.What is the jspInit() method?
	The jspInit() method of the javax.servlet.jsp.JspPage interface is similar to the init() method of servlets. This method is invoked by the container only once when a JSP page is initialized. It can be overridden by a page author to initialize resources such as database and network connections, and to allow a JSP page to read persistent configuration data.
4.What is the _jspService() method?
	SThe _jspService() method of the javax.servlet.jsp.HttpJspPage interface is invoked every time a new request comes to a JSP page. This method takes the HttpServletRequest and HttpServletResponse objects as its arguments. A page author cannot override this method, as its implementation is provided by the container.
5.What is the jspDestroy() method?
	The jspDestroy() method of the javax.servlet.jsp.JspPage interface is invoked by the container when a JSP page is about to be destroyed. This method is similar to the destroy() method of servlets. It can be overridden by a page author to perform any cleanup operation such as closing a database connection.
6.What JSP lifecycle methods can I override?
	You cannot override the _jspService() method within a JSP page. You can however, override the jspInit() and jspDestroy() methods within a JSP page. jspInit() can be useful for allocating resources like database connections, network connections, and so forth for the JSP page. It is good programming practice to free any allocated resources within jspDestroy().
7.How can I override the jspInit() and jspDestroy() methods within a JSP page?
	The jspInit() and jspDestroy() methods are each executed just once during the lifecycle of a JSP page and are typically declared as JSP declarations:
	<%!
	public void jspInit() {
	. . .
	}
	%>
	<%!
	public void jspDestroy() {
	. . .
	}
	%>
	8.What are implicit objects in JSP?
	Implicit objects in JSP are the Java objects that the JSP Container makes available to developers in each page. These objects need not be declared or instantiated by the JSP author. They are automatically instantiated by the container and are accessed using standard variables; hence, they are called implicit objects.The implicit objects available in JSP are as follows:
request
response
pageContext
session
application
out
config
page
exception
	The implicit objects are parsed by the container and inserted into the generated servlet code. They are available only within the jspService method and not in any declaration.
	9.What are the different types of JSP tags?
	The different types of JSP tags are as follows:
	
	10.What are JSP directives?
JSP directives are messages for the JSP engine. i.e., JSP directives serve as a message from a JSP page to the JSP container and control the processing of the entire page
They are used to set global values such as a class declaration, method implementation, output content type, etc.
They do not produce any output to the client.
Directives are always enclosed within <%@ ….. %> tag.
Ex: page directive, include directive, etc.
11.What is page directive?
A page directive is to inform the JSP engine about the headers or facilities that page should get from the environment.
Typically, the page directive is found at the top of almost all of our JSP pages.
There can be any number of page directives within a JSP page (although the attribute – value pair must be unique).
The syntax of the include directive is: <%@ page attribute="value">
Example:<%@ include file="header.jsp" %>
12.What are the attributes of page directive?
	There are thirteen attributes defined for a page directive of which the important attributes are as follows:
import: It specifies the packages that are to be imported.
session: It specifies whether a session data is available to the JSP page.
contentType: It allows a user to set the content-type for a page.
isELIgnored: It specifies whether the EL expressions are ignored when a JSP is translated to a servlet.
13.What is the include directive?
	There are thirteen attributes defined for a page directive of which the important attributes are as follows:
The include directive is used to statically insert the contents of a resource into the current JSP.
This enables a user to reuse the code without duplicating it, and includes the contents of the specified file at the translation time.
The syntax of the include directive is as follows: <%@ include file = "FileName" %>
This directive has only one attribute called file that specifies the name of the file to be included.
14.What are the JSP standard actions?
The JSP standard actions affect the overall runtime behavior of a JSP page and also the response sent back to the client.
They can be used to include a file at the request time, to find or instantiate a JavaBean, to forward a request to a new page, to generate a browser-specific code, etc.
Ex: include, forward, useBean,etc. object
15.What are the standard actions available in JSP?
	The standard actions available in JSP are as follows:
<jsp:include>: It includes a response from a servlet or a JSP page into the current page. It differs from an include directive in that it includes a resource at request processing time, whereas the include directive includes a resource at translation time.
<jsp:forward>: It forwards a response from a servlet or a JSP page to another page.
<jsp:useBean>: It makes a JavaBean available to a page and instantiates the bean.
<jsp:setProperty>: It sets the properties for a JavaBean.
<jsp:getProperty>: It gets the value of a property from a JavaBean component and adds it to the response.
<jsp:param>: It is used in conjunction with <jsp:forward>;, <jsp:, or plugin>; to add a parameter to a request. These parameters are provided using the name-value pairs.
<jsp:plugin>: It is used to include a Java applet or a JavaBean in the current JSP page.
16.What is the <jsp:useBean> standard action?
	The <jsp:useBean> standard action is used to locate an existing JavaBean or to create a JavaBean if it does not exist. It has attributes to identify the object instance, to specify the lifetime of the bean, and to specify the fully qualified classpath and type.
17.What are the scopes available in <jsp:useBean>?
	The scopes available in <jsp:useBean> are as follows:
page scope:: It specifies that the object will be available for the entire JSP page but not outside the page.
request scope: It specifies that the object will be associated with a particular request and exist as long as the request exists.
application scope: It specifies that the object will be available throughout the entire Web application but not outside the application.
session scope: It specifies that the object will be available throughout the session with a particular client.
18.What is the <jsp:forward> standard action?
The <jsp:forward> standard action forwards a response from a servlet or a JSP page to another page.
The execution of the current page is stopped and control is transferred to the forwarded page.
The syntax of the <jsp:forward> standard action is :  <jsp:forward page="/targetPage" /> Here, targetPage can be a JSP page, an HTML page, or a servlet within the same context.
If anything is written to the output stream that is not buffered before <jsp:forward>, an IllegalStateException will be thrown.
	Note : Whenever we intend to use <jsp:forward> or <jsp:include> in a page, buffering should be enabled. By default buffer is enabled.
19.What is the <jsp:include> standard action?
	The <jsp:include> standard action enables the current JSP page to include a static or a dynamic resource at runtime. In contrast to the include directive, the include action is used for resources that change frequently. The resource to be included must be in the same context.The syntax of the <jsp:include> standard action is as follows:
	<jsp:include page="targetPage" flush="true"/>
	Here, targetPage is the page to be included in the current JSP.
20.What is the difference between include directive and include action
	21.Differentiate between pageContext.include and jsp:include?
	The <jsp:include> standard action and the pageContext.include() method are both used to include resources at runtime. However, the pageContext.include() method always flushes the output of the current page before including the other components, whereas <jsp:include> flushes the output of the current page only if the value of flush is explicitly set to true as follows:
	<jsp:include page="/index.jsp" flush="true"/>
	22.What is the jsp:setProperty action?
	You use jsp:setProperty to give values to properties of beans that have been referenced earlier. You can do this in two contexts. First, you can use jsp:setProperty after, but outside of, a jsp:useBean element, as below:
	<jsp:useBean id="myName" ... />
	...
	<jsp:setProperty name="myName" property="myProperty" ... />
	In this case, the jsp:setProperty is executed regardless of whether a new bean was instantiated or an existing bean was found.  A second context in which jsp:setProperty can appear is inside the body of a jsp:useBean element, as below:
	<jsp:useBean id="myName" ... >
	...
	<jsp:setProperty name="myName"
	property="someProperty" ... />
	</jsp:useBean>
Here, the jsp:setProperty is executed only if a new object was instantiated, not if an existing one was found.
23.What is the jsp:getProperty action?
	The <jsp:getProperty> action is used to access the properties of a bean that was set using the <jsp:getProperty> action. The container converts the property to a String as follows:
If it is an object, it uses the toString() method to convert it to a String.
If it is a primitive, it converts it directly to a String using the valueOf() method of the corresponding Wrapper class.
The syntax of the <jsp:getProperty> method is: <jsp:getProperty name="Name" property="Property" />
Here, name is the id of the bean from which the property was set. The property attribute is the property to get. A user must create or locate a bean using the <jsp:useBean> action before using the <jsp:getProperty> action.
24.What is the <jsp:param> standard action?
	The <jsp:param> standard action is used with <jsp:include> or <jsp:forward> to pass parameter names and values to the target resource. The syntax of the <jsp:param> standard action is as follows:
	<jsp:param name="paramName" value="paramValue"/>
25.What is the jsp:plugin action ?
	This action lets you insert the browser-specific OBJECT or EMBED element needed to specify that the browser run an applet using the Java plugin.
26.What are scripting elements?
	JSP scripting elements let you insert Java code into the servlet that will be generated from the current JSP page. There are three forms:
1. Expressions of the form <%= expression %> that are evaluated and inserted into the output,
2. Scriptlets of the form <% code %> that are inserted into the servlet's service method,
3. Declarations of the form <%! code %> that are inserted into the body of the servlet class, outside of any existing methods.
27.What is a scriptlet?
	A scriptlet contains Java code that is executed every time a JSP is invoked. When a JSP is translated to a servlet, the scriptlet code goes into the service() method. Hence, methods and variables written in scriptlets are local to the service() method. A scriptlet is written between the <% and %> tags and is executed by the container at request processing time.
28.What are JSP declarations?
	As the name implies, JSP declarations are used to declare class variables and methods in a JSP page. They are initialized when the class is initialized. Anything defined in a declaration is available for the whole JSP page. A declaration block is enclosed between the <%! and %> tags. A declaration is not included in the service() method when a JSP is translated to a servlet.
29.What is a JSP expression?
	A JSP expression is used to write an output without using the out.print statement. It can be said as a shorthand representation for scriptlets. An expression is written between the <%= and %> tags. It is not required to end the expression with a semicolon, as it implicitly adds a semicolon to all the expressions within the expression tags.
30.How is scripting disabled?
	Scripting is disabled by setting the scripting-invalid element of the deployment descriptor to true. It is a subelement of jsp-property-group. Its valid values are true and false. The syntax for disabling scripting is as follows:
	<jsp-property-group>
	<url-pattern>*.jsp</url-pattern>
	<scripting-invalid>true</scripting-invalid>
	</jsp-property-group>
Servlet
	What is the Servlet?
	A servlet is a Java programming language class that is used to extend the capabilities of servers that host applications accessed by means of a request- response programming model.
2.What are the new features added to Servlet 2.5?
	Following are the changes introduced in Servlet 2.5:
A new dependency on J2SE 5.0
Support for annotations
Loading the class
Several web.xml conveniences
A handful of removed restrictions
Some edge case clarifications
3.What are the uses of Servlet?
	Typical uses for HTTP Servlets include:
Processing and/or storing data submitted by an HTML form.
Providing dynamic content, e.g. returning the results of a database query to the client.
A Servlet can handle multiple request concurrently and be used to develop high performance system
Managing state information on top of the stateless HTTP, e.g. for an online shopping cart system which manages shopping carts for many concurrent customers and maps every request to the right customer.
4.What are the advantages of Servlet over CGI?
	Servlets have several advantages over CGI:
A Servlet does not run in a separate process. This removes the overhead of creating a new process for each request.
A Servlet stays in memory between requests. A CGI program (and probably also an extensive runtime system or interpreter) needs to be loaded and started for each CGI request.
There is only a single instance which answers all requests concurrently. This saves memory and allows a Servlet to easily manage persistent data.
Several web.xml conveniences
A handful of removed restrictions
Some edge case clarifications
5.What are the phases of the servlet life cycle?
	The life cycle of a servlet consists of the following phases:
Servlet class loading : For each servlet defined in the deployment descriptor of the Web application, the servlet container locates and loads a class of the type of the servlet. This can happen when the servlet engine itself is started, or later when a client request is actually delegated to the servlet.
Servlet instantiation : After loading, it instantiates one or more object instances of the servlet class to service the client requests.
Initialization (call the init method) : After instantiation, the container initializes a servlet before it is ready to handle client requests. The container initializes the servlet by invoking its init() method, passing an object implementing the ServletConfig interface. In the init() method, the servlet can read configuration parameters from the deployment descriptor or perform any other one-time activities, so the init() method is invoked once and only once by the servlet container.
Request handling (call the service method) : After the servlet is initialized, the container may keep it ready for handling client requests. When client requests arrive, they are delegated to the servlet through the service() method, passing the request and response objects as parameters. In the case of HTTP requests, the request and response objects are implementations of HttpServletRequest and HttpServletResponse respectively. In the HttpServlet class, the service() method invokes a different handler method for each type of HTTP request, doGet() method for GET requests, doPost() method for POST requests, and so on.
Removal from service (call the destroy method) : A servlet container may decide to remove a servlet from service for various reasons, such as to conserve memory resources. To do this, the servlet container calls the destroy() method on the servlet. Once the destroy() method has been called, the servlet may not service any more client requests. Now the servlet instance is eligible for garbage collection
	The life cycle of a servlet is controlled by the container in which the servlet has been deployed.
	
6.Why do we need a constructor in a servlet if we use the init method?
	Even though there is an init method in a servlet which gets called to initialize it, a constructor is still required to instantiate the servlet. Even though you as the developer would never need to explicitly call the servlet's constructor, it is still being used by the container (the container still uses the constructor to create an instance of the servlet). Just like a normal POJO (plain old java object) that might have an init method, it is no use calling the init method if you haven't constructed an object to call it on yet.
7.How the servlet is loaded?
	A servlet can be loaded when:
First request is made.
Server starts up (auto-load).
There is only a single instance which answers all requests concurrently. This saves memory and allows a Servlet to easily manage persistent data.
Administrator manually loads.
8.How a Servlet is unloaded?
	A servlet is unloaded when:
Server shuts down.
Administrator manually unloads.
9.What is Servlet interface?
	The central abstraction in the Servlet API is the Servlet interface. All servlets implement this interface, either directly or , more commonly by extending a class that implements it.
	
	Note: Most Servlets, however, extend one of the standard implementations of that interface, namely javax.servlet.GenericServlet andjavax.servlet.http.HttpServlet.
People who read this, also read:-
	10.What is the GenericServlet class?
	GenericServlet is an abstract class that implements the Servlet interface and the ServletConfig interface. In addition to the methods declared in these two interfaces, this class also provides simple versions of the lifecycle methods init and destroy, and implements the log method declared in the ServletContext interface.
	Note: This class is known as generic servlet, since it is not specific to any protocol.
11.What's the difference between GenericServlet and HttpServlet?
12.Why is HttpServlet declared abstract?
	The HttpServlet class is declared abstract because the default implementations of the main service methods do nothing and must be overridden. This is a convenience implementation of the Servlet interface, which means that developers do not need to implement all service methods. If your servlet is required to handle doGet() requests for example, there is no need to write a doPost() method too.
13.Can servlet have a constructor ?
	One can definitely have constructor in servlet.Even you can use the constrctor in servlet for initialization purpose,but this type of approch is not so common. You can perform common operations with the constructor as you normally do.The only thing is that you cannot call that constructor explicitly by the new keyword as we normally do.In the case of servlet, servlet container is responsible for instantiating the servlet, so the constructor is also called by servlet container only.
14.What are the types of protocols supported by HttpServlet ?
	It extends the GenericServlet base class and provides a framework for handling the HTTP protocol. So, HttpServlet only supports HTTP and HTTPS protocol.
15.What is the difference between doGet() and doPost()?
	When to use doGet() and when doPost()?
	Always prefer to use GET (As because GET is faster than POST), except mentioned in the following reason:
If data is sensitive
Data is greater than 1024 characters
If your application don't need bookmarks.
	17.How do I support both GET and POST from the same Servlet?
	The easy way is, just support POST, then have your doGet method call your doPost method:
	public void doGet(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException
	{
	doPost(request, response);
	}
	18.Should I override the service() method?
	We never override the service method, since the HTTP Servlets have already taken care of it . The default service function invokes the doXXX() method corresponding to the method of the HTTP request.For example, if the HTTP request method is GET, doGet() method is called by default. A servlet should override the doXXX() method for the HTTP methods that servlet supports. Because HTTP service method check the request method and calls the appropriate handler method, it is not necessary to override the service method itself. Only override the appropriate doXXX() method.
	19.How the typical servlet code look like ?
	
	20.What is a servlet context object?
	A servlet context object contains the information about the Web application of which the servlet is a part. It also provides access to the resources common to all the servlets in the application. Each Web application in a container has a single servlet context associated with it.
	21.What are the differences between the ServletConfig interface and the ServletContext interface?
	22.What's the difference between forward() and sendRedirect() methods?
	23.What is the difference between the include() and forward() methods?
Peop
	24.What's the use of the servlet wrapper classes??
	The HttpServletRequestWrapper and HttpServletResponseWrapper classes are designed to make it easy for developers to create custom implementations of the servlet request and response types. The classes are constructed with the standard HttpServletRequest and HttpServletResponse instances respectively and their default behaviour is to pass all method calls directly to the underlying objects.
	25.What is the directory structure of a WAR file?
	
	26.What is a deployment descriptor?
	A deployment descriptor is an XML document with an .xml extension. It defines a component's deployment settings. It declares transaction attributes and security authorization for an enterprise bean. The information provided by a deployment descriptor is declarative and therefore it can be modified without changing the source code of a bean.
	The JavaEE server reads the deployment descriptor at run time and acts upon the component accordingly.
	27.What is the difference between the getRequestDispatcher(String path) method of javax.servlet.ServletRequest interface and javax.servlet.ServletContext interface?
	28.What is preinitialization of a servlet?
	A container does not initialize the servlets as soon as it starts up, it initializes a servlet when it receives a request for that servlet first time. This is called lazy loading. The servlet specification defines the element, which can be specified in the deployment descriptor to make the servlet container load and initialize the servlet as soon as it starts up. The process of loading a servlet before any request comes in is called preloading or preinitializing a servlet.
	29.What is the <load-on-startup> element?
	The <load-on-startup> element of a deployment descriptor is used to load a servlet file when the server starts instead of waiting for the first request. It is also used to specify the order in which the files are to be loaded. The <load-on-startup> element is written in the deployment descriptor as follows:
	<servlet>
	<servlet-name>ServletName</servlet-name>
	<servlet-class>ClassName</servlet-class>
	<load-on-startup>1</load-on-startup>
	</servlet>
	Note: The container loads the servlets in the order specified in the <load-on-startup> element.
	What is Servlet Chaining?
	Servlet Chaining is a method where the output of one servlet is piped into a second servlet. The output of the second servlet could be piped into a third servlet, and so on. The last servlet in the chain returns the output to the Web browser.
	43.How are filters?
	Filters are Java components that are used to intercept an incoming request to a Web resource and a response sent back from the resource. It is used to abstract any useful information contained in the request or response. Some of the important functions performed by filters are as follows:
Security checks
Modifying the request or response
Data compression
Logging and auditing
Response compression
	Filters are configured in the deployment descriptor of a Web application. Hence, a user is not required to recompile anything to change the input or output of the Web application.
	44.What are the functions of an intercepting filter?
	The functions of an intercepting filter are as follows:
It intercepts the request from a client before it reaches the servlet and modifies the request if required.
It intercepts the response from the servlet back to the client and modifies the request if required.
There can be many filters forming a chain, in which case the output of one filter becomes an input to the next filter. Hence, various modifications can be performed on a single request and response.
	
	45.What are the functions of the Servlet container?
	The functions of the Servlet container are as follows:
Lifecycle management : It manages the life and death of a servlet, such as class loading, instantiation, initialization, service, and making servlet instances eligible for garbage collection.
Communication support : It handles the communication between the servlet and the Web server.
Multithreading support : It automatically creates a new thread for every servlet request received. When the Servlet service() method completes, the thread dies.
Declarative security : It manages the security inside the XML deployment descriptor file.
JSP support : The container is responsible for converting JSPs to servlets and for maintaining them.
                        
Document Text Contents
Page 2

o Extension ClassLoader -

JRE/lib/ext or any directory

denoted by java.ext.dirs

o Application ClassLoader

- CLASSPATH environment

variable, -classpath or -cp opti

on, Class-Path attribute of

Manifest inside JAR file.

Aggregation

o If a class have an entity reference, it is known
as Aggregation. Aggregation represents HAS-
A relationship.

o We are passing object instance from outside
in Aggregation.

Uses

o For Code Reusability
o Inheritance should be used only if the

relationship is-a is maintained throughout
the lifetime of the objects involved;
otherwise, aggregation is the best choice

Address.java



http://javarevisited.blogspot.sg/2012/03/how-to-create-and-execute-jar-file-in.html

Page 14

file during the translation phase–when the page is converted
to a servlet.

executing the specified page (a JSP page or a servlet) during
the request processing phase–when the page is requested by
a user.

The include directive is used to statically insert the contents
of a resource into the current JSP.

The include standard action enables the current JSP page to
include a static or a dynamic resource at runtime.

Use the include directive if the file changes rarely. It’s the
fastest mechanism.

Use the include action only for content that changes often,
and if which page to include cannot be decided until the
main page is requested.

21.Differentiate between pageContext.include and jsp:include?
The <jsp:include> standard action and the pageContext.include() method are both used
to include resources at runtime. However, the pageContext.include() method always
flushes the output of the current page before including the other components,
whereas <jsp:include> flushes the output of the current page only if the value of flush is
explicitly set to true as follows:

<jsp:include page="/index.jsp" flush="true"/>

22.What is the jsp:setProperty action?
You use jsp:setProperty to give values to properties of beans that have been referenced
earlier. You can do this in two contexts. First, you can use jsp:setProperty after, but
outside of, a jsp:useBean element, as below:

<jsp:useBean id="myName" ... />

...

<jsp:setProperty name="myName" property="myProperty" ... />

In this case, the jsp:setProperty is executed regardless of whether a new bean was instantiated
or an existing bean was found.

A second context in which jsp:setProperty can appear is inside the body of
a jsp:useBean element, as below:

<jsp:useBean id="myName" ... >

...

<jsp:setProperty name="myName"

property="someProperty" ... />

</jsp:useBean>

Here, the jsp:setProperty is executed only if a new object was instantiated, not if an existing one
was found.

23.What is the jsp:getProperty action?

Page 15

The <jsp:getProperty> action is used to access the properties of a bean that was set using the
<jsp:getProperty> action. The container converts the property to a String as follows:

 If it is an object, it uses the toString() method to convert it
to a String.

 If it is a primitive, it converts it directly to a String using the
valueOf() method of the corresponding Wrapper class.

 The syntax of the <jsp:getProperty> method
is: <jsp:getProperty name="Name"
property="Property" />

Here, name is the id of the bean from which the property was set. The property attribute is the
property to get. A user must create or locate a bean using the <jsp:useBean> action before
using the <jsp:getProperty> action.

24.What is the <jsp:param> standard action?
The <jsp:param> standard action is used with <jsp:include> or <jsp:forward> to pass parameter
names and values to the target resource. The syntax of the <jsp:param> standard action is as
follows:
<jsp:param name="paramName" value="paramValue"/>

25.What is the jsp:plugin action ?
This action lets you insert the browser-specific OBJECT or EMBED element needed to specify that
the browser run an applet using the Java plugin.

26.What are scripting elements?
JSP scripting elements let you insert Java code into the servlet that will be generated from the
current JSP page. There are three forms:

1. Expressions of the form <%= expression %> that are
evaluated and inserted into the output,

2. Scriptlets of the form <% code %> that are inserted into
the servlet's service method,

3. Declarations of the form <%! code %> that are inserted
into the body of the servlet class, outside of any existing
methods.

27.What is a scriptlet?
A scriptlet contains Java code that is executed every time a JSP is invoked. When a JSP is
translated to a servlet, the scriptlet code goes into the service() method. Hence, methods and
variables written in scriptlets are local to the service() method. A scriptlet is written between
the <% and %> tags and is executed by the container at request processing time.

Page 27

 Logging and auditing

 Response compression

Filters are configured in the deployment descriptor of a Web application. Hence, a user is not
required to recompile anything to change the input or output of the Web application.

44.What are the functions of an intercepting filter?

The functions of an intercepting filter are as follows:

 It intercepts the request from a client before it reaches
the servlet and modifies the request if required.

 It intercepts the response from the servlet back to the
client and modifies the request if required.

 There can be many filters forming a chain, in which case
the output of one filter becomes an input to the next
filter. Hence, various modifications can be performed on
a single request and response.

45.What are the functions of the Servlet container?

The functions of the Servlet container are as follows:

 Lifecycle management : It manages the life and death of
a servlet, such as class loading, instantiation,
initialization, service, and making servlet instances
eligible for garbage collection.

 Communication support : It handles the communication
between the servlet and the Web server.

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