Difference between <%@include and jsp:include

<%@ include includes file at compile time. anychanges to that file won't affect the result.

jsp:include includes file at run time. changes to that file affect the result

Q: What is a output comment?

A: A comment that is sent to the client in the viewable page source.The JSP engine handles an output comment as uninterpreted HTML text, returning the comment in the HTML output sent to the client. You can see the comment by viewing the page source from your Web browser.

JSP Syntax

Example 1

Displays in the page source:

Q: What is a Hidden Comment?

A: 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 --%>

<%@ page language="java" %>

A Hidden Comment

<%-- This comment will not be visible to the client in the page source --%>

Q: What is a Expression?

A: 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
<%= someexpression %>
<%= (new java.util.Date()).toLocaleString() %>
You cannot use a semicolon to end an expression

Q: What is a Declaration?

A: A declaration declares one or more variables or methods for use later in the JSP source file.
A declaration must contain at least one complete declarative statement. You can declare any number of variables or methods within one declaration tag, as long as they are separated by semicolons. The declaration must be valid in the scripting language used in the JSP file.

<%! somedeclarations %>
<%! int i = 0; %>
<%! int a, b, c; %>

Q: What is a Scriptlet?

A: 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
1.Declare variables or methods to use later in the file (see also Declaration).

2.Write expressions valid in the page scripting language (see also Expression).

3.Use any of the JSP implicit objects or any object declared with a tag.
You must write plain text, HTML-encoded text, or other JSP tags outside the scriptlet.

Scriptlets are executed at request time, when the JSP engine processes the client request. If the scriptlet produces output, the output is stored in the out object, from which you can display it.

Q: What are implicit objects? List them?

A: 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

Q: Difference between forward and sendRedirect?

A: 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.

Q: What are the different scope valiues for the ?

A: The different scope values for are

1. page
2. request

Q: Explain the life-cycle mehtods in JSP?

A: THe generated servlet class for a JSP page implements the HttpJspPage interface of the javax.servlet.jsp package. Hte 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().
The jspInit()- The container calls the jspInit() to initialize te servlet instance.It is called before any other method, and is called only once for a servlet instance.
The _jspservice()- The container calls the _jspservice() for each request, passing it the request and the response objects.
The jspDestroy()- The container calls this when it decides take the instance out of service. It is the last method called n the servlet instance.

Well Formed XML --- An XML that contains correct syntax
Valid XML --- Well formed XML that which conforms to the rules of DTD

DTD is includes in the XML file.


DTD has given in another file

XML Namespace --- To avoid name conflict we can use namespaces

Sample Name Space :


Five Escape Characters :

> = >
< = <
& = &
' = '
" = "e;

CDATA --- Data inside CDATA won't get parsed.

Type of JDBC drivers :

1. JDBC - ODBC Bridge drivers :
--- Connects java client with ODBC database system
--- requires non-java code to be installed on the system
--- Converts JDBC Calls in to ODBC calls which in turn converts this one into client (Oracle, Sql Server, MySql etc) Calls.

2. Native-API Partly Java Drivers :
--- requires native code library API to access Database. Fast compared with All java driver since it is in native code
--- Converts JDBC Calls in to Client API (Oracle, Sql Server, MySql etc) Calls

3. Net-protocol All-Java Drivers :
--- Converts JDBC Calls into DBMS independent net protocol (middleware).Middleware may use any type of driver to database access

4. Native-protocol All-Java Drivers :
--- Convert JDBC calls to network protocol used by DBMS. This is the practical solution for intranet.

There are three types of statement :

1) Regular statement
2) Prepared statement (precompiles SQL Statement)
3) Callable statement (TO call stored procedure)
CallableStatement cst = con.prepareCall("{call SHOW_SUPPLIERS ?}");

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