AccessCounts.jsp Page that demonstrates JSP declarations. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <!-- Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. --> <HTML> <HEAD> <TITLE>JSP Declarations</TITLE> <META NAME="keywords" CONTENT="JSP,declarations,JavaServer,Pages,servlets"> <META NAME="description" CONTENT="A quick example of JSP declarations."> <LINK REL=STYLESHEET HREF="JSP-Styles.css" TYPE="text/css"> </HEAD> <BODY> <H1>JSP Declarations</H1> <%! private int accessCount = 0; %> <H2>Accesses to page since server reboot: <%= ++accessCount %></H2> </BODY> </HTML>
Aug 07
AccessCounts.jsp Page that demonstrates JSP declarations.
Aug 07
PreparedStatements.java An example to test the timing differences resulting from repeated raw queries vs. repeated calls
package cwp;
import java.sql.*;
/** An example to test the timing differences resulting
* from repeated raw queries vs. repeated calls to
* prepared statements. These results will vary dramatically
* among database servers and drivers. With my setup
* and drivers, Oracle prepared statements took only half
* the time that raw queries required when using a modem
* connection, and took only 70% of the time that
* raw queries required when using a fast LAN connection.
* Sybase times were identical in both cases.
*
*/
public class PreparedStatements {
public static void main(String[] args) {
if (args.length < 5) {
printUsage();
return;
}
String vendorName = args[4];
int vendor = DriverUtilities.getVendor(vendorName);
if (vendor == DriverUtilities.UNKNOWN) {
printUsage();
return;
}
String driver = DriverUtilities.getDriver(vendor);
String host = args[0];
String dbName = args[1];
String url =
DriverUtilities.makeURL(host, dbName, vendor);
String username = args[2];
String password = args[3];
// Use "print" only to confirm it works properly,
// not when getting timing results.
boolean print = false;
if ((args.length > 5) && (args[5].equals("print"))) {
print = true;
}
Connection connection =
getConnection(driver, url, username, password);
if (connection != null) {
doPreparedStatements(connection, print);
doRawQueries(connection, print);
}
}
private static void doPreparedStatements(Connection conn,
boolean print) {
try {
String queryFormat =
"SELECT lastname FROM employees WHERE salary > ?";
PreparedStatement statement =
conn.prepareStatement(queryFormat);
long startTime = System.currentTimeMillis();
for(int i=0; i<40; i++) {
statement.setFloat(1, i*5000);
ResultSet results = statement.executeQuery();
if (print) {
showResults(results);
}
}
long stopTime = System.currentTimeMillis();
double elapsedTime = (stopTime - startTime)/1000.0;
System.out.println("Executing prepared statement " +
"40 times took " +
elapsedTime + " seconds.");
} catch(SQLException sqle) {
System.out.println("Error executing statement: " + sqle);
}
}
public static void doRawQueries(Connection conn,
boolean print) {
try {
String queryFormat =
"SELECT lastname FROM employees WHERE salary > ";
Statement statement = conn.createStatement();
long startTime = System.currentTimeMillis();
for(int i=0; i<40; i++) {
ResultSet results =
statement.executeQuery(queryFormat + (i*5000));
if (print) {
showResults(results);
}
}
long stopTime = System.currentTimeMillis();
double elapsedTime = (stopTime - startTime)/1000.0;
System.out.println("Executing raw query " +
"40 times took " +
elapsedTime + " seconds.");
} catch(SQLException sqle) {
System.out.println("Error executing query: " + sqle);
}
}
private static void showResults(ResultSet results)
throws SQLException {
while(results.next()) {
System.out.print(results.getString(1) + " ");
}
System.out.println();
}
private static Connection getConnection(String driver,
String url,
String username,
String password) {
try {
Class.forName(driver);
Connection connection =
DriverManager.getConnection(url, username, password);
return(connection);
} catch(ClassNotFoundException cnfe) {
System.err.println("Error loading driver: " + cnfe);
return(null);
} catch(SQLException sqle) {
System.err.println("Error connecting: " + sqle);
return(null);
}
}
private static void printUsage() {
System.out.println("Usage: PreparedStatements host " +
"dbName username password " +
"oracle|sybase [print].");
}
}
Aug 06
এএসপি . নেট এম ভি সি এর উপর কিছু প্রশ্ন এবং উত্তর । Some questions and Answers on ASP.NET MVC
Some questions and Answers on ASP NET MVC
Aug 06
Some Questions and Answers on Razor View Engine
Some Questions and Answers on Razor View Engine
Aug 06
নোড.জেএস (Node. Js) টিউটোরিয়াল
মীর তাওহীদুল ইসলাম
ওয়েব ডেভেলপার
আজকে আপনাদের সামনে হাজির হলাম নোড জে এস এর টিউটোরিয়াল নিয়ে। আশা করি আপনাদের ভাল লাগবে।
নোড জে এস জাভাস্ক্রিপ্ট এর উপর ভিত্তি করে গড়ে ওঠা খুবই শক্তিশালী একটি ফ্রেমওয়ার্ক বা প্লাটফর্ম যা গুগল ক্রোমের জাভাস্ক্রিপ্ট ভি এইট ইঞ্জিনে (V8 Engine) এ তৈরি করা হয়েছে।
এই নোড জে এস ব্যাবহার হয় বিভিন্ন ধরনের ওয়েব অ্যাপলিকেশন তৈরিতে যেমনঃ অনলাইনে ভিডিও দেখার সাইট তৈরিতে, এক পেইজের অ্যাপলিকেশন তৈরিতে বা অন্যান্য ওয়েব অ্যাপলিকেশন তৈরিতে।
এই নোড জে এস একটি মুক্ত উৎস, সম্পূর্ণ ফ্রী এবং এটা সারা বিশ্বের হাজার হাজার ডেভেলপার এর ব্যাবহারের একটি উৎস।
এই টিউটোরিয়ালটি তৈরি করা হয়েছে সফটওয়্যার প্রোগ্রামারদের জন্য যারা নোড জে এস এর ব্যাসিক ও স্থাপত্য ধারনা গুলো সহজ সরল ভাবে শিখতে চায়।
এই টিউটোরিয়ালটি আপনাকে নোড জে এস এর উপাদান গুলো সম্পর্কে উপযুক্ত উদাহারনসহ খুব ভাল ধারনা দিবে।
এই টিউটোরিয়ালটি শুরুর পূর্বে অবশ্যই আপনার জাভাস্ক্রিপ্ট সম্পর্কে বেসিক ধারনা থাকতে হবে কারন আমরা এখন নোড জে এস ব্যাবহার করে একটি ওয়েব অ্যাপ্লিকেশন তৈরি করতে যাচ্ছি। এটা আপনার জন্য আরও ভালো হবে যদি আপনার আরও অন্যান্য ওয়েব প্রযুক্তি যেমন- এইচ টি এম এল (HTML), সি এস এস (CSS) , অ্যাজাক্স (AJAX) ইত্যাদি সম্পর্কেও বেসিক ধারনা থাকে।
আর এই টিউটোরিয়ালে যে উদাহারন গুলো থাকবে তা অবশ্যই নিজে নিজে চেষ্টা করতে হবে।
তাই প্রাথমিক ভাবে নিচে একটা উদাহারন কোড দেওয়া হলঃ
/*Hello World ! My First Programme In Node. Js*/
Console.log (“Hello World !”) ;
Aug 06
Install Kentico CMS in Localhost
Install Kentico CMS in Localhost
https://www.youtube.com/watch?v=KFcnunBi2GM
Aug 06
EmployeeCreation.java: Make a simple “employees” table using the database utilities
package cwp;
import java.sql.*;
/** Make a simple "employees" table using DatabaseUtilities.
*/
public class EmployeeCreation {
public static Connection createEmployees(String driver,
String url,
String username,
String password,
boolean close) {
String format =
"(id int, firstname varchar(32), lastname varchar(32), " +
"language varchar(16), salary float)";
String[] employees =
{"(1, 'Wye', 'Tukay', 'COBOL', 42500)",
"(2, 'Britt', 'Tell', 'C++', 62000)",
"(3, 'Max', 'Manager', 'none', 15500)",
"(4, 'Polly', 'Morphic', 'Smalltalk', 51500)",
"(5, 'Frank', 'Function', 'Common Lisp', 51500)",
"(6, 'Justin', 'Timecompiler', 'Java', 98000)",
"(7, 'Sir', 'Vlet', 'Java', 114750)",
"(8, 'Jay', 'Espy', 'Java', 128500)" };
return(DatabaseUtilities.createTable(driver, url,
username, password,
"employees",
format, employees,
close));
}
public static void main(String[] args) {
if (args.length < 5) {
printUsage();
return;
}
String vendorName = args[4];
int vendor = DriverUtilities.getVendor(vendorName);
if (vendor == DriverUtilities.UNKNOWN) {
printUsage();
return;
}
String driver = DriverUtilities.getDriver(vendor);
String host = args[0];
String dbName = args[1];
String url =
DriverUtilities.makeURL(host, dbName, vendor);
String username = args[2];
String password = args[3];
createEmployees(driver, url, username, password, true);
}
private static void printUsage() {
System.out.println("Usage: EmployeeCreation host dbName " +
"username password oracle|sybase.");
}
}
Aug 06
extract relevant data from a DBResults
# QueryViewer.java An interactive database query viewer. Connects to the specified Oracle or Sybase database, executes a query, and presents the results in a JTable. Uses the following file:
* DBResultsTableModel.java Simple class that tells a JTable how to extract relevant data from a DBResults object (which is used to store the results from a database query).
############################################################################
package cwp;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
/** An interactive database query viewer. Connects to
* the specified Oracle or Sybase database, executes a query,
* and presents the results in a JTable.
*
*/
public class QueryViewer extends JFrame
implements ActionListener{
public static void main(String[] args) {
new QueryViewer();
}
private JTextField hostField, dbNameField,
queryField, usernameField;
private JRadioButton oracleButton, sybaseButton;
private JPasswordField passwordField;
private JButton showResultsButton;
Container contentPane;
private JPanel tablePanel;
public QueryViewer () {
super("Database Query Viewer");
WindowUtilities.setNativeLookAndFeel();
addWindowListener(new ExitListener());
contentPane = getContentPane();
contentPane.add(makeControlPanel(), BorderLayout.NORTH);
pack();
setVisible(true);
}
/** When the "Show Results" button is pressed or
* RETURN is hit while the query textfield has the
* keyboard focus, a database lookup is performed,
* the results are placed in a JTable, and the window
* is resized to accommodate the table.
*/
public void actionPerformed(ActionEvent event) {
String host = hostField.getText();
String dbName = dbNameField.getText();
String username = usernameField.getText();
String password =
String.valueOf(passwordField.getPassword());
String query = queryField.getText();
int vendor;
if (oracleButton.isSelected()) {
vendor = DriverUtilities.ORACLE;
} else {
vendor = DriverUtilities.SYBASE;
}
if (tablePanel != null) {
contentPane.remove(tablePanel);
}
tablePanel = makeTablePanel(host, dbName, vendor,
username, password,
query);
contentPane.add(tablePanel, BorderLayout.CENTER);
pack();
}
// Executes a query and places the result in a
// JTable that is, in turn, inside a JPanel.
private JPanel makeTablePanel(String host,
String dbName,
int vendor,
String username,
String password,
String query) {
String driver = DriverUtilities.getDriver(vendor);
String url = DriverUtilities.makeURL(host, dbName, vendor);
DBResults results =
DatabaseUtilities.getQueryResults(driver, url,
username, password,
query, true);
JPanel panel = new JPanel(new BorderLayout());
if (results == null) {
panel.add(makeErrorLabel());
return(panel);
}
DBResultsTableModel model =
new DBResultsTableModel(results);
JTable table = new JTable(model);
table.setFont(new Font("Serif", Font.PLAIN, 17));
table.setRowHeight(28);
JTableHeader header = table.getTableHeader();
header.setFont(new Font("SansSerif", Font.BOLD, 13));
panel.add(table, BorderLayout.CENTER);
panel.add(header, BorderLayout.NORTH);
panel.setBorder
(BorderFactory.createTitledBorder("Query Results"));
return(panel);
}
// The panel that contains the textfields, checkboxes,
// and button.
private JPanel makeControlPanel() {
JPanel panel = new JPanel(new GridLayout(0, 1));
panel.add(makeHostPanel());
panel.add(makeUsernamePanel());
panel.add(makeQueryPanel());
panel.add(makeButtonPanel());
panel.setBorder
(BorderFactory.createTitledBorder("Query Data"));
return(panel);
}
// The panel that has the host and db name textfield and
// the driver radio buttons. Placed in control panel.
private JPanel makeHostPanel() {
JPanel panel = new JPanel();
panel.add(new JLabel("Host:"));
hostField = new JTextField(15);
panel.add(hostField);
panel.add(new JLabel(" DB Name:"));
dbNameField = new JTextField(15);
panel.add(dbNameField);
panel.add(new JLabel(" Driver:"));
ButtonGroup vendorGroup = new ButtonGroup();
oracleButton = new JRadioButton("Oracle", true);
vendorGroup.add(oracleButton);
panel.add(oracleButton);
sybaseButton = new JRadioButton("Sybase");
vendorGroup.add(sybaseButton);
panel.add(sybaseButton);
return(panel);
}
// The panel that has the username and password textfields.
// Placed in control panel.
private JPanel makeUsernamePanel() {
JPanel panel = new JPanel();
usernameField = new JTextField(10);
passwordField = new JPasswordField(10);
panel.add(new JLabel("Username: "));
panel.add(usernameField);
panel.add(new JLabel(" Password:"));
panel.add(passwordField);
return(panel);
}
// The panel that has textfield for entering queries.
// Placed in control panel.
private JPanel makeQueryPanel() {
JPanel panel = new JPanel();
queryField = new JTextField(40);
queryField.addActionListener(this);
panel.add(new JLabel("Query:"));
panel.add(queryField);
return(panel);
}
// The panel that has the "Show Results" button.
// Placed in control panel.
private JPanel makeButtonPanel() {
JPanel panel = new JPanel();
showResultsButton = new JButton("Show Results");
showResultsButton.addActionListener(this);
panel.add(showResultsButton);
return(panel);
}
// Shows warning when bad query sent.
private JLabel makeErrorLabel() {
JLabel label = new JLabel("No Results", JLabel.CENTER);
label.setFont(new Font("Serif", Font.BOLD, 36));
return(label);
}
}
Aug 05
EmployeeTest2.java: A test case for the database utilities. Prints results formatted as an HTML table.
package cwp;
import java.sql.*;
/** Connect to Oracle or Sybase and print "employees" table
* as an HTML table.
*
*/
public class EmployeeTest2 {
public static void main(String[] args) {
if (args.length < 5) {
printUsage();
return;
}
String vendorName = args[4];
int vendor = DriverUtilities.getVendor(vendorName);
if (vendor == DriverUtilities.UNKNOWN) {
printUsage();
return;
}
String driver = DriverUtilities.getDriver(vendor);
String host = args[0];
String dbName = args[1];
String url =
DriverUtilities.makeURL(host, dbName, vendor);
String username = args[2];
String password = args[3];
String query = "SELECT * FROM employees";
DBResults results =
DatabaseUtilities.getQueryResults(driver, url,
username, password,
query, true);
System.out.println(results.toHTMLTable("CYAN"));
}
private static void printUsage() {
System.out.println("Usage: EmployeeTest2 host dbName " +
"username password oracle|sybase.");
}
}
