how to get connection using JDBC

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
/**-----------------------------------------------------------------------------
The following class provides an example of using JDBC to connect to an
*Oracle database. The one phase of JDBC that is the most difficult and
* hard to achieve portability, is when connecting. This phase requires
* that the Java database application specify driver-specific information that
* JDBC requires in the form of a database URL.
* If you run into problems while trying to simply make a connection, check
* if they match any of the following: *
* Connection fails with the message "Class no found" *
--------------------------------------------------
Connection fails with the message "Class no found" *
--------------------------------------------------
*This message usually results from not having the JDBC driver in your
*CLASSPATH. Ensure that if you are including
*.zip and *.jar in your * CLASSPATH, that your enter them explicity. If you put all of your *.class * files and the ojdbc14.jar file containing the Oracle-JDBC driver into * /u02/lib, your CLASSPATH should read /u02/lib:/u02/lib/ojdbc14.jar. *
*Connection fails with the message "Driver no found" *
---------------------------------------------------
*In this case, you did not register the JDBC driver with the DriverManager *class.
This example application describes several ways to register a * JDBC driver. Sometimes developers using the Class.forName() method of *registering a JDBC driver encounter an inconsistency between the JDBC *specification and some JVM implementations. You should thus use the*Class.forName().netInstance() method as a workaround. *
* When attempting to make a database connection, your application must first
* request a java.sql.Connection implementation from the DriverManager. You will
* also use a database URL and whatever properties your JDBC driver requires
* (generally a user ID and password). The DriverManager in turn will search
* through all of the known java.sql.Driver implementations for the one that
* connects with the URL you provided. If it exhausts all the implementations
* without finding a match, it throws an exception back to your application.
* Once a Driver recognizes your URL, it creates a database connection using
* the properties you specified. It then provides the DriverManager with a * java.sql.
Connection implementation representing that database connection. The
* DriverManager then passes that Connection object back to the application.
* At this point, you may be wondering how the JDBC DriverManager learns about
* a new driver implementation. The DriverManager actually keeps a list of
* classes that implement that java.sql.Driver interface. Something needs to
*register the Driver implementation for any potential database drivers it
*might require with the DriverManager. JDBC requires a Driver class to
*register itself with the DriverManager when it is initiated. The act of
* instantiating a Driver class thus enters it in the DriverManager's list.
* * This class (ConnectionExample) provides three ways to register a driver.
* ----------------------------------------------------------------------------- *
@version 1.0 * @author Jeffrey M. Hunter (jhunter@idevelopment.info) * @author http://www.idevelopment.info *
----------------------------------------------------------------------------- */
public class ConnectionExample {
final String driverClass = "oracle.jdbc.driver.OracleDriver";
final String connectionURLThin = "jdbc:oracle:thin:@jeffreyh3:1521:CUSTDB";
final String connectionURLOCI = "jdbc:oracle:oci8:@CUSTDB_JEFFREYH3";
final String userID = "scott";
final String userPassword = "tiger";
final String queryString = "SELECT" + " user " + " , TO_CHAR(sysdate, 'DD-MON-YYYY HH24:MI:SS') " + "FROM dual";
/**
* The following method provides an example of how to connect to a database
* by registering the JDBC driver using the DriverManager class. This method
* requires you to hardcode the loading of a Driver implementation in
* your application. this alternative is the least desirable since it
* requires a rewrite and recompile if your database or database driver
* changes. */
public void driverManager() {
Connection con = null;
Statement stmt = null;
ResultSet rset = null;
try {
System.out.print("\n");
System.out.print("+-------------------------------+\n");
System.out.print(" USING DriverManager CLASS \n");
System.out.print("+-------------------------------+\n");
System.out.print("\n");
System.out.print(" Loading JDBC Driver -> " + driverClass + "\n"); DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
System.out.print(" Connecting to -> " + connectionURLThin + "\n");
con = DriverManager.getConnection(connectionURLThin, userID, userPassword); System.out.print(" Connected as -> " + userID + "\n");
System.out.print(" Creating Statement...\n");
stmt = con.createStatement ();
System.out.print(" Opening ResultsSet...\n");
rset = stmt.executeQuery(queryString);
while (rset.next()) {
System.out.println(" Results...");
System.out.println(" User -> " + rset.getString(1));
System.out.println(" Sysdate -> " + rset.getString(2));
}
System.out.print(" Closing ResultSet...\n");
rset.close();
System.out.print(" Closing Statement...\n");
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
if (con != null) {
try {
con.rollback();
} catch (SQLException e1) {
e1.printStackTrace();
}
}
}
finally {
if (con != null) {
try {
System.out.print(" Closing down all connections...\n\n");
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}