How to connect to a MySQL database with Java? (JDBC Example)
要连接MySQL数据库，需添加MySQL Connector/J驱动，使用JDBC URL（如jdbc:mysql://localhost:3306/myapp?useSSL=false&serverTimezone=UTC），调用DriverManager.getConnection()，并确保MySQL服务运行、权限正确、端口开放。
To connect to a MySQL database from Java, you use the MySQL Connector/J — a JDBC driver provided by Oracle. The process involves adding the driver to your project, loading it (optional in newer versions), and establishing a connection using DriverManager.getConnection() with the correct URL, username, and password.
1. Add MySQL JDBC Driver to Your Project
You need the MySQL Connector/J JAR file. The easiest way is to include it via a build tool:
-
Maven: Add this dependency to your
pom.xml:
If you're not using Maven, download the JAR from dev.mysql.com and add it to your classpath.
2. Use the Correct JDBC URL Format
MySQL JDBC URLs follow this pattern:
jdbc:mysql://[host]:[port]/[database]?[options]Common examples:
- Local database:
jdbc:mysql://localhost:3306/myapp - With SSL and time zone:
jdbc:mysql://localhost:3306/myapp?useSSL=false&serverTimezone=UTC
For MySQL 8 , always include serverTimezone to avoid timezone-related exceptions. Also set useSSL=false unless you've configured SSL properly.
3. Write the Connection Code
Here’s a minimal working example:
import java.sql.*;public class MySQLConnection {
public static void main(String[] args) {
String url = "jdbc:mysql://localhost:3306/myapp?useSSL=false&serverTimezone=UTC";
String user = "root";
String password = "password";
try (Connection conn = DriverManager.getConnection(url, user, password)) {
System.out.println("Connected to MySQL!");
} catch (SQLException e) {
e.printStackTrace();
}
}
}
Notes:
- No need to call
Class.forName("com.mysql.cj.jdbc.Driver")explicitly since JDBC 4.0 — the driver auto-registers. - Use try-with-resources to auto-close the
Connection. - Handle
SQLException— it’s a checked exception.
4. Verify Credentials and Server Status
If the connection fails, check these first:
- Is MySQL server running? (e.g.,
sudo systemctl status mysqlon Linux) - Does the user have permission to connect from your host? Try:
mysql -u root -p -h localhost - Is the database name spelled correctly and does it exist?
- Are firewall or network settings blocking port 3306?
Also confirm your MySQL user has remote access rights if connecting from another machine.
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