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Connecting with Java

This guide explains how to establish a connection between a Java application and a MySQL database using the mysql-connector-j JDBC driver. It walks through the necessary setup, configuration, and execution of a simple SQL query.

Variables

Certain parameters must be provided to establish a successful connection to a MySQL database. Below is a breakdown of each required variable, its purpose, and where to find it. Here’s what each variable represents:

Variable

Description

Purpose

USER

MySQL username, from the Elestio service overview page

Identifies the database user who has permission to access the MySQL database.

PASSWORD

MySQL password, from the Elestio service overview page

The authentication key is required for the specified USER to access the database.

HOST

Hostname for MySQL connection, from the Elestio service overview page

The address of the server hosting the MySQL database.

PORT

Port for MySQL connection, from the Elestio service overview page

The network port used to connect to MySQL. The default port is 3306.

DATABASE

Database Name for MySQL connection, from the Elestio service overview page

The name of the database being accessed. A MySQL instance can contain multiple databases.

These values can usually be found in the Elestio service overview details as shown in the image below, make sure to take a copy of these details and add it to the code moving ahead.

image.png

Prerequisites

  • Install Java
    • Check if Java is installed by running: java -version.
    • If not installed, download it from oracle.com or install OpenJDK.
  • Install MySQL Connector/J

Code

Once all prerequisites are set up, create a new file named MySQLConnect.java and add the following code:

import java.sql.*;
import java.util.*;

public class MySQLConnect {
    public static void main(String[] args) {
        Map<String, String> config = new HashMap<>();
        for (int i = 0; i < args.length - 1; i += 2)
            config.put(args[i], args[i + 1]);

        String url = String.format("jdbc:mysql://%s:%s/%s?useSSL=true",
                config.get("-host"), config.get("-port"), config.get("-database"));

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            try (Connection conn = DriverManager.getConnection(url, config.get("-username"), config.get("-password"));
                 Statement stmt = conn.createStatement();
                 ResultSet rs = stmt.executeQuery("SELECT VERSION()")) {
                System.out.println("Connected to MySQL");
                if (rs.next()) System.out.println("MySQL Version: " + rs.getString(1));
            }
        } catch (Exception e) {
            System.err.println("Connection error: " + e.getMessage());
        }
    }
}

To compile and run the Java program, use the following commands in your terminal:

javac MySQLConnect.java && java -cp mysql-connector-j-9.3.0.jar:. MySQLConnect -host HOST -port PORT -database DATABASE -username avnadmin -password PASSWORD

If the connection is successful, the terminal will display output similar to:

Connected to MySQL
MySQL Version: 8.0.41
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