释放mysql连接

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;

public class DatabaseUtil {
    private static HikariDataSource dataSource;

    static {
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl("jdbc:mysql://localhost:3306/mydatabase");
        config.setUsername("username");
        config.setPassword("password");
        config.addDataSourceProperty("cachePrepStmts", "true");
        config.addDataSourceProperty("prepStmtCacheSize", "250");
        config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");

        dataSource = new HikariDataSource(config);
    }

    public static Connection getConnection() throws SQLException {
        return dataSource.getConnection();
    }
}

try (Connection conn = DatabaseUtil.getConnection();
     PreparedStatement ps = conn.prepareStatement("SELECT * FROM users WHERE id = ?")) {
    ps.setInt(1, userId);
    try (ResultSet rs = ps.executeQuery()) {
        while (rs.next()) {
            // 处理结果集
        }
    }
} catch (SQLException e) {
    e.printStackTrace();
}

Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
    conn = DatabaseUtil.getConnection();
    ps = conn.prepareStatement("SELECT * FROM users WHERE id = ?");
    ps.setInt(1, userId);
    rs = ps.executeQuery();
    while (rs.next()) {
        // 处理结果集
    }
} catch (SQLException e) {
    e.printStackTrace();
} finally {
    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    if (ps != null) {
        try {
            ps.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    if (conn != null) {
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}