Several methods and examples for connecting to databases in Java projects

Several methods and examples for connecting to databases in Java projects
1. The most primitive writing method (also for Beginners)
First import the database to connect to the basic class, and then the other is simple. In actual operation, you only need to load the driver class and then call the SQL statement. The following is a simple program example.
// Select. java
Import java.net. URL;
Import java. SQL .*;
Class Select {
Public static void main (String [] args ){
Try {
// Create a connection URL
String url = "jdbc: odbc: wombat ";
// Establish a connection
Connection con = DriverManager. getConnection (url, "usre", "; password ");
// Create statement
Statement stmt = con. createStatement ();
// Execute the query and return the result set
ResultSet rs = stmt.exe cuteQuery ("SELECT a, B, c, d, key FROM Table1 ");
Stmt. close ();
Con. close ();
}
Catch (Exception ex ){
Ex. printStackTrace ();
}
}
}
2. Database connection pool:
As far as I know, most projects now use database connection pools. There is no other reason. In addition to improving network throughput and increasing system performance, there is also a so-called encapsulation of database operations, and most system operations on the database are limited to the centralized scope of CRUD, effective encapsulation. The subsequent programming is quite simple and easy. Other companies offer such dedicated database components for sale.
The connection pool mentioned above also has two types of branches. One is to directly use the connection pool provided by the container, and the other is to write the connection pool by yourself.