Connection conn = drivermanager.getconnection ("Jdbc:odbc:bbs");

Connection conn = drivermanager.getconnection ("Jdbc:odbc:bbs");

This is the phrase that JDBC connects to the database, connection is an interface, DriverManager is a class, and the Getconnection () method is a static method

The reason they can connect with the = number

Because the getconnection () method returns an  instance of a class that implements the connection interface

In fact, connection is a class or interface, and under normal circumstances a variable is declared with a class,

And the interface is a specialized class, which is equivalent to the virtual base class in C + +, as long as the class implements this interface is equivalent to inherit the interface

And like a parent class variable = An instance of a subclass is common in Java, and since that's OK

So like an interface variable = An instance of a subclass can also be a row

The Getconnection () method is a static method

Class . Method () This form of method-----class method, i.e., this method can be used even if the class is not instantiated,

There are also objects. Static methods ()

And the general method can not

A factory model is a class that is called a class factory to produce instances of classes (more interfaces)

And this factory class usually has only one copy.

Connection conn = drivermanager.getconnection("");

There is no instantiation of the factory class here, only one copy

Returns an instance of a class that implements the connection interface with a static method class

Purpose---to make use of connection instances, there is no need to care about how classes of connection interfaces change

Connection conn = drivermanager.getconnection ("Jdbc:odbc:bbs");