How Class.forName() load the Driver and DriverManager.getConnection() return connection?

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!!! JDBC Frequently Asked Questions !!!

How Class.forName() load the Driver and DriverManager.getConnection() return connection?

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!!!Answer!!!- From Technical Expert

These are the steps happing inside
Step 1.
Class.forName("com.mysql.jdbc.Driver") load the Driver.
Step 2.
In the com.mysql.jdbc.Driver class there is static bock .
That will execute because of static bock.
static
{
try
{
DriverManager.registerDriver(new Driver());
}
catch(SQLException E)
{
throw new RuntimeException("Can't register driver!");
}
}
This static block call DriverManager.registerDriver(new Driver());

Step 3.
Inside DriverManager.registerDriver() method.
public static synchronized void registerDriver(java.sql.Driver driver)
    throws SQLException {

    DriverInfo di = new DriverInfo();
    di.driver = driver;
    di.driverClass = driver.getClass();
    di.driverClassName = di.driverClass.getName();
    drivers.addElement(di);
    println("registerDriver: " + di);
}

DriverManager class create a Vector name "drivers" and add the Driver class to the vector.
Now In the Vector we have com.mysql.jdbc.Driver object.

Step 4.
To get connection we can
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/testDB","username","password");
In this method , it search for the Driver in the vector , if available then connect and return connection.
for (int i = 0; i < drivers.size(); i++) {
     DriverInfo di = (DriverInfo)drivers.elementAt(i);
// if "jdbc:mysql" keywork which is input , match with the driver in the vector then {
Connection result = di.driver.connect(url, info);

}
}
Return connection;
This class getting jdbc:mysql://localhost:3306/testDB as input . This class check for the driver based on "jdbc:mysql" in this case and connect the driver.

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!!! JDBC Frequently Asked Questions !!!

How Class.forName() load the Driver and DriverManager.getConnection() return connection?

Click to View Answer Below

!!!Answer!!!- From Technical Expert

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