What is factory pattern?

DAO is the operation of adding, deleting, modifying and checking the data in the database, and the factory mode is the encapsulation of the database connection. Different databases have different connections (such as code 2); DAO functions: 1. DAO is used to encapsulate the Data Source; just

For example, Connection conn = DAOFacotry.createConnection(); you can put Driver. URL. username, passpword in DAO and then change the database type. For example, if you want to change MSSQL to Oracle, you only need to change getConnection in DAOFacory.

() inside Driver.URL. and the like; 2. DAO also encapsulates all operations on the database (such as the most basic CRUD operations); for example, if you want to insert a new user, then you only need to provide

An insertUser(User user) method is enough; the specific operation is implemented in DAO; then when you want to call DAO, you only need to know that insertUser(User) is used to insert a new user; you do not need to know

How is it achieved.