Answer the following questions
1. What
is the use of SetAutoCommit()?
We can use the setAutoCommit() method. This method belongs to the Connection interface and, it accepts a boolean value. If you pass true to this method it turns on the auto-commit feature of the database and, if you pass false to this method it turns off the auto-commit feature of the database.
2. Write
short note on: JDBC API Packages.
The Java Database Connectivity (JDBC) API provides universal data access from
the Java programming language. Using the JDBC API, you can access virtually any
data source, from relational databases to spreadsheets and flat files. JDBC
technology also provides a common base on which tools and alternate interfaces
can be built.
The JDBC API is comprised of two packages:
1. java.sql
2. javax.sql
To use the JDBC API with a particular database management system, you need a
JDBC technology-based driver to mediate between JDBC technology and the
database.
3. What
is database?
JDBC or Java Database Connectivity is a Java API to connect and execute the
query with the database. It is a specification from Sun microsystems that
provides a standard abstraction(API or Protocol) for java applications to
communicate with various databases.
4. What
is meant by JDBC driver?
JDBC Driver is a software component that enables Java application to interact
with the database. JDBC Driver translates the standard JDBC API calls to the
DBMS specific API calls. JDBC drivers implement the defined interfaces in the
JDBC API, for interacting with the database server.
5. What
is the use of JDBC API?
The Java Database Connectivity (JDBC) API provides universal data access from
the Java programming language. Using the JDBC API, you can access virtually any
data source, from relational databases to spreadsheets and flat files. JDBC
technology also provides a common base on which tools and alternate interfaces
can be built.
The JDBC API is comprised of two packages:
1. java.sql
2. javax.sql
To use the JDBC API with a particular database management system, you need a
JDBC technology-based driver to mediate between JDBC technology and the
database.
6. What
is ResultSetMetaData?
The ResultSetMetaData provides information about the obtained ResultSet object
like, the number of columns, names of the columns, datatypes of the columns,
name of the table etc… Following are some methods of ResultSetMetaData class.
7. What
is DatabaseMetaData?
database metadata refers to data about database data or, more elaborately, the
information about tables, views, column types, column names, result sets,
stored procedures, and databases. Java's JDBC metadata API provides the means
to retrieve that information through Java code.
8. What
are two different ways used to implement threading in java programs?
1. void. start() It is used to start the execution of the thread.
2. void. run() It is used to do an action for a thread.
3. static void. sleep() It sleeps a thread for the specified amount of time.
4. static Thread. currentThread()
5. void. join()
6. int. getPriority()
7. void. setPriority()
8. String. getName()
9. Explain
the concept of thread synchronization?
Synchronization Multithreading introduces asynchronous behavior to the
programs. If a thread is writing some data another thread may be reading the same
data at that time. This may bring inconsistency. When two or more threads wants
to access a shared resource, then it must ensure that the resource will be used
by only one thread at an instant of time. The mechanism of this process is
called synchronization.
10. What
is a thread?
A task is completed by a program with the sequence of steps, called as process.
Each specific task in a process is called thread. When there are multiple
threads execute simultaneously, it is called multithreading. A thread is a
program's path of execution. A thread is a line of execution. lightweight sub
process, a smallest unit of processing. Threads are independent, if there
occurs exception in one thread, it doesn't affect other threads. It shares a
common memory area.
11. Explain
the following methods.
a. Sleep()
The sleep() method is a static method of Thread class and it makes the thread
sleep/stop working for a specific amount of time. The sleep() method throws an
InterruptedException if a thread is interrupted by other threads, that means
Thread.
b. resume()
The resume() method of thread class is only used
with suspend() method. This method is used to resume a thread which was
suspended using suspend() method. This method allows the suspended thread to
start again.
c. getPriority()
The getPriority() method of thread class
is used to check the priority of the thread. When we create a
thread, it has some priority assigned to it. Priority of thread can either be
assigned by the JVM or by the programmer explicitly while creating the thread.
The thread's priority is in the range of 1 to 10.
d. getName()
The getName() method is a part of File class. This function returns the Name of
the given file object. The function returns a string object which contains the
Name of the given file object. If the abstract path does not contain any name
then a null string is returned.
e. wait()
When wait() method is called, the calling thread stops its execution until
notify() or notifyAll() method is invoked by some other Thread.
f. notify()
The notify() method is defined in the Object
class, which is Java's top-level class. It's used to wake up only one
thread that's waiting for an object, and that thread then begins execution.
The thread class notify() method is used to wake up a single thread.
12. What
is Networking?
Java Networking is a concept of connecting two or more computing devices
together so that we can share resources. Java socket programming provides
facility to share data between different computing devices.
13. What
are the advantages of networking?
1. Flexible
& powerful
2. Very
sufficient
3. Updated
Information can be used to send only between devices
4. Low
network traffic if efficient use
14. What
is Protocol? List out at least two protocols.
A protocol is a set of rules to govern the data transfer between the devices.
The rules are used for the following purposes.
1. For compressing the data.
2. For sending device to indicate that it has finished sending a message.
3. For receiving device to indicate that it has received a message.
List out 2 Protocals
1. Transmission control Protocol (TCP)
This is a communication protocol that computers uses to communicate over a
network. TCP divides message into stream of packets which are sent and then
reassembled at the destination.
2. Internet Protocol (IP)
Internet protocol is addressing protocol. It is always used together with
TCP. IP addresses of packet, routes them through different nodes and networks
until it reaches its final destination. TCP/IP is perhaps the most used
standard protocol for connecting computer networks.
15. What
is Internet?
Internet is a global network that connects
billions of computers across the world with each other and to the World Wide
Web. It uses standard internet protocol suite (TCP/IP) to connect billions of
computer users worldwide. It is set up by using cables such as optical fibers
and other wireless and networking technologies. At present, internet is the
fastest mean of sending or exchanging information and data between computers
across the world.
16. Explain
use of Socket class.
The java.net package in the Java platform provides a class, Socket , that
implements one side of a two-way connection between your Java program and
another program on the network. The Socket class sits on top of a
platform-dependent implementation, hiding the details of any particular system
from your Java program.
18. Explain
the use of ServerSocket class.
ServerSocket Class is used for providing system-independent implementation of
the server-side of a client/server Socket Connection. The constructor for
ServerSocket throws an exception if it can't listen on the specified port (for
example, the port is already being used). It is widely used so the applications
of java.
19. Explain
the use of DatagramSocket class.
Class DatagramSocket. This class represents a socket for sending and receiving
datagram packets. A datagram socket is the sending or receiving point for a
packet delivery service. Each packet sent or received on a datagram socket is
individually addressed and routed.
20. Define
protocol list TCP and UDP.
1. TCP
2. UDP
3. IP
21. What
is Internet Addressing? Give the purpose of InetAddress class?
The java. net. InetAddress class provides methods to get the IP address of any
hostname. An IP address is represented by 32-bit or 128-bit unsigned number.
InetAddress can handle both IPv4 and IPv6 addresses
Purpose :
This class is used to encapsulate both the numerical IP address and the domain
name for that address. A host on the Internet can be represented either in
dotted decimal format as an IP address or as a hostname such as yahoo.com. In
Java, such addresses are represented by the java.net.InetAddress class. This
class can fill a variety of tasks, from resolving an IP address to looking up
the hostname.
22. Describe
the use of following:
a. Reserved
sockets
Reserved Socket are definded as that the particular sockets are reserved for
the particular services that is called as reserved socket. Socket number
between 0 to 1023 are reserved for popular application protocols (e.g., Port 80
for HTTP, Port 443 for HTTPS, Port 21 for FTP, Port 23 for Telnet, Port 25 for
SMTP, Port 110 for POP3, etc.
b. DNS
(Domain Naming Service)
The domain name system (DNS) is a naming database in which internet domain
names are located and translated into Internet Protocol (IP) addresses. The
domain name system maps the name people use to locate a website to the IP
address that a computer uses to locate that website.
For example, if someone types "example.com" into a web
browser, a server behind the scenes maps that name to the corresponding IP
address. An IP address is similar in structure to 203.0.113.72.
23. Explain
the use of following methods of DatagramPacket class with example:
a. getPort()
The getPort () method of Java DatagramPacket class returns the port number on
the remote host to which this datagram is being sent or from which it was
received.
Syntax
public int getPort ()
b. getData()
The getData() method of Java DatagramPacket
class returns the data buffer. Any data that is to be received or is to be
sent, firstly starts from the offset in the buffer and then runs for length
long.
Syntax
public byte[] getData()
24. What
is proxy server? Give the purpose of proxy server.
A proxy server is a system or router that provides a gateway between users and
the internet. Therefore, it helps prevent cyber attackers from entering a
private network. It is a server, referred to as an “intermediary” because it
goes between end-users and the web pages they visit online.
Purpose
A proxy server is a special type of network node that alters packets that pass
through it, masking their IP addresses and making it seem that the packets
originated at the proxy system. Proxy servers may be a natural part of your
network architecture, or they may be third-party servers that provide anonymity
to their users.
25. What
is Servlet? Explain the servlet types.
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. Although servlets can respond to any type
of request, they are commonly used to extend the applications hosted by web
servers.
Generic Servlet:
Generic Servlet is a direct division of Servlet type. The servlet is
written in this form
This Servlet does not follow any protocol or is not bound to any form of
protocol rules as to how to write the servlet and in which order. This results
in having no support from any HTTP protocol from the system. We can write
servlets easily in Generic Servlet making it common for any methods used in the
system. Log method is also used in Generic Servlet which is defined in
ServletContext Interface so that all the changes made in the servlet can be
monitored easily.
Syntax : javax.servlet.GenericServlet
HTTP Servlet:
HTTP Servlet is a subclass of Generic Servlet. The servlet is called as
javax.servlet.HttpServlet.
As the name suggests, they have HTTP support and can work in any HTTP
environment with the help of servers. When there are HTTP-specific methods to
be used, we can continue with HTTP servlet. HTTP Servlet can be used only with
HTTP protocol and for other protocols, we should use Generic Servlet. Service
methods should specify the HTTP protocol in the services handled making it most
specific only to HTTP methods.
27. Explain
session tracking.
Session simply means a particular interval of time.
Session Tracking is a way to maintain state (data) of an user. It is also known
as session management in servlet. Http protocol is a stateless so we need to
maintain state using session tracking techniques. Each time user requests to
the server, server treats the request as the new request. So we need to
maintain the state of an user to recognize to particular user.
28. Explain
types of cookies.
A cookie is a small amount of data stored on your computer, tablet, or phone,
created by and read by website servers. “Cookies were developed during a time
when most web usage was anonymous. “They became a way for websites to know
about you.”
Cookies are kind of like nametags, in that they allow a website to recognize
you, without having to store information about you on their own servers—whenever
you visit a site, it sees the cookie on your device and knows who you are.
30. Explain
URL rewriting.
URL rewriting is the process of
modifying Uniform Resource Locators (URLs) for various purposes. The URL as a
“web address” is a string that, when entered into the browser bar field,
directs the browser to move to a given site and page. Changing the URL can help
with user access and site visibility; it can also be used by hackers to
redirect users without their knowledge or “trap” them in a certain site.
31. Explain
hidden form field.
A hidden field let web developers include data that cannot be seen or modified
by users when a form is submitted. A hidden field often stores what database
record that needs to be updated when the form is submitted.
32. What
is scriptlet in JSP?
This tag allow user to insert java code in JSP. The statement which is written
will be moved to jspservice() using JSP container while generating servlet from
JSP. When client make a request, JSP service method is invoked and after that
the content which is written inside the scriptlet tag executes.
<html><body><% out.print("GeeksforGeeks"); %>
<!-- scriptlet tag --></body></html>
33. What
is hibernate?
Hibernate is an open source object relational mapping (ORM) tool that provides
a framework to map object-oriented domain models to relational databases for
web applications.
Object relational mapping is based on the containerization of objects and the
abstraction that provides that capacity. Abstraction makes it possible to
address, access and manipulate objects without having to consider how they are
related to their data sources.
34. What
is ORM?
Object-Relational Mapping (ORM) is a technique that lets you query and
manipulate data from a database using an object-oriented paradigm. When talking
about ORM, most people are referring to a library that implements the
Object-Relational Mapping technique, hence the phrase "an ORM".
35. What
are the core interfaces of Hibernate?
1. Session Interface : The basic interface for all hibernate
applications. The instances are light weighted and can be created and destroyed
without expensive process.
2. SessionFactory interface : The delivery of session objects to
hibernate applications is done by this interface. For the whole application,
there will be generally one SessionFactory and can be shared by all the
application threads.
3. Configuration Interface : Hibernate bootstrap action is
configured by this interface. The location specification is specified by specific
mapping documents, is done by the instance of this interface.
4. Transaction Interface : This is an optional interface. This
interface is used to abstract the code from a transaction that is implemented
such as a JDBC / JTA transaction.
5. Query and Criteria interface : The queries from the user are
allowed by this interface apart from controlling the flow of the query
execution.
36. Mention
some of the advantages of using ORM over JDBC.
1. It allows business code access the objects rather than Database tables.
2. It hides the details of SQL queries from OO logic.
3. It is based on JDBC “under hood”.
4. Dealing with database implementation is not required.
5. Entities are based on business concepts rather than database structures.
38. Mention
two components of Hibernate configuration object.
The Configuration object is the first
Hibernate object you create in any Hibernate application. It is usually created
only once during application initialization. It represents a configuration or
properties file required by the Hibernate.
The Configuration object provides two keys components −
Database Connection − This is handled through one or more
configuration files supported by Hibernate. These files are
hibernate.properties and hibernate.cfg.xml.
Class Mapping Setup − This component creates the connection between
the Java classes and database tables.
39. How
is SQL query created in Hibernate?
Use Session. createSQLQuery(String query) to create the SQLQuery object and
execute it. Application will create a native SQL query from the session with
the createSQLQuery() method on the Session interface −
Syntax : public SQLQuery createSQLQuery(String sqlString) throws
HibernateException
40. What
does HQL stand for?
Hibernate Query Language (HQL) is an object-oriented query
language, similar to SQL, but instead of operating on tables and columns, HQL
works with persistent objects and their properties.
41. How
can we add criteria to a SQL query?
The Hibernate Session interface provides createCriteria() method, which can be
used to create a Criteria object that returns instances of the persistence
object's class when your application executes a criteria query.
Following is the simplest example of a criteria query is one, which will simply
return every object that corresponds to the Employee class.
Criteria cr = session.createCriteria(Employee.class);
List results = cr.list();
42. What
is SessionFactory?
The SessionFactory is a thread safe object and used by all the threads of an
application. The SessionFactory is a heavyweight object; it is usually created
during application start up and kept for later use. You would need one
SessionFactory object per database using a separate configuration file.
43. Is
Session a thread-safe object?
A Session is an inexpensive, non-threadsafe object that should be used once,
for a single request, a conversation, single unit of work, and then discarded.
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