Java JDBC连接数据库：异常处理与优化示例-蒲公英云

Java JDBC连接数据库：异常处理与优化示例

在Java中，使用JDBC（Java Database Connectivity）来连接数据库是一个基本的过程。以下是一个包含异常处理和性能优化的示例：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class JdbcConnectionExample {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/mydatabase";
    private static final String USER = "username";
    private static final String PASS = "password";
    public static void main(String[] args) {
        Connection connection = null;
        try {
            // 1. Register JDBC driver
            Class.forName("com.mysql.jdbc.Driver");
            // 2. Open a connection
            connection = DriverManager.getConnection(DB_URL, USER, PASS);
            // 3. Execute SQL statements
            String query = "SELECT * FROM users";
            ResultSet resultSet = connection.createStatement().executeQuery(query);
            // 4. Process and close the result set
            if (resultSet != null) {
                while (resultSet.next()) {
                    System.out.println("User ID: " + resultSet.getInt("id") +
                                              ", Username: " + resultSet.getString("username"));
                }
                resultSet.close();
            }
        } catch (SQLException | ClassNotFoundException e) {
            // Handle exceptions
            e.printStackTrace();
        } finally {
            // Closing the connection, whether successful or not
            if (connection != null) {
                try {
                    connection.close();
                } catch (SQLException e) {
                    // handle closing connections
                    e.printStackTrace();
                }
            }
        }
    }
}