hi all,

i got this example from a website, but unfortunately i cant understand some cording in that source.

the green color lines are the difficult points that i could not understand.

also the database name, user name and password has not specified at anywhere in this cord.

how can i make this cord to run without problems....?

please help me.



import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.ConnectionPoolDataSource;
import javax.sql.PooledConnection;

public class MainClass {
public static void main(String[] args) {
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;

try {
connection = getConnection();
// Do work with connection
statement = connection.createStatement();
String selectEmployeesSQL = "SELECT * FROM employees";
resultSet = statement.executeQuery(selectEmployeesSQL);

while (resultSet.next()) {
printEmployee(resultSet);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
}// nothing we can do
}
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
} // nothing we can do
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
} // nothing we can do
}
}
}

private static Connection getConnection() throws NamingException, SQLException {
InitialContext initCtx = createContext();
String jndiName = "HrDS";
ConnectionPoolDataSource dataSource = (ConnectionPoolDataSource) initCtx.lookup(jndiName);
PooledConnection pooledConnection = dataSource.getPooledConnection();
return pooledConnection.getConnection(); // Obtain connection from pool
}

private static InitialContext createContext() throws NamingException {
Properties env = new Properties();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.rmi.registry.RegistryContextFactory");
env.put(Context.PROVIDER_URL, "rmi://localhost:1099");
InitialContext context = new InitialContext(env);
return context;
}

private static void printEmployee(ResultSet resultSet) throws SQLException {
System.out.print(resultSet.getInt("employee_id")+", ");
System.out.print(resultSet.getString("last_name")+", ");
System.out.print(resultSet.getString("first_name")+", ");
System.out.println(resultSet.getString("email"));
}

}

If that's part of a JSP, never look at that example again.
That sort of code (or indeed ANY code) does NOT belong in a JSP.
Nor should anyone, ever, directly reference any of the classes in the com.sun packages.
This code references a connection pool provided by an application server.
The application server itself will hold the actual database configuration, including database URL, username, password, driverclass, etc. etc..