How to Connect to a Database Using JDBC?

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You must build a connection before accessing a database. In order to connect to a database, your specified JDBC driver class must be loaded by the JVM classloader.Your JDBC driver documentation provides the class name to use. You will have to use java.sql.DriverManager's getConnection() method to create a database connection. This method takes an argument which identifies your database you wishing to connect to through a JDBC URL. A JDBC URL starts with "jdbc:" indicating the protocol (JDBC).The JDBC URL you use will vary with the database you use (such as MySQL, Oracle, Sybase, and so on).
The following code is an example opening a MySQL database connection,

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class Program {

  public static void main(String... args) {
    Connection con = null;

    try {
      Class.forName("org.gjt.mm.mysql.Driver").newInstance();
    }
    catch(Exception e) {
      System.out.println("Exception: " + e.getMessage());
      return ;
    }

    try {
      con = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb",
        "usr", "sql");

      if(!con.isClosed())
        System.out.println("Successfully connected to " +
          "MySQL server using TCP/IP...");

    } catch(Exception e) {
      System.out.println("Exception: " + e.getMessage());
    } finally {
      try {
        if(con != null)
          con.close();
      }
      catch(SQLException e) {
      }
    }
  }
}

We try to load the org.gjt.mm.mysql.Driver class which is MySQL JDBC driver class, and then catch the ClassNotFoundException if it is thrown. Then we try to connect mydb database on local MySQL server, and attempt to connect as user "usr", whose password is "sql". The connection returned by the method DriverManager.getConnection is an open connection you can use to create JDBC statements that pass your SQL statements to the DBMS.