import java.sql.*;
import javax.sql.*;

public final class JdbcUtil {

	/**
	 * @param args
	 */
	private static String url = "jdbc:mysql://localhost:3306/jdbc"; // jdbc:mysql:///jdbc 本地默认端口可以省略
	private static String user = "root";
	private static String password = "123456";
	
	private JdbcUtil() { }
	
	static {
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			throw new ExceptionInInitializerError(e);
		}
	}

	public static Connection getConnection() throws SQLException{
		return DriverManager.getConnection(url, user, password);
	}
	
	public static void free(ResultSet rs, Statement st, Connection conn) {
		try {
			if (rs != null) {
				rs.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				if (st != null) {
					st.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				if (conn != null) {
					try {
						conn.close();
					} catch (SQLException e) {
						e.printStackTrace();
					}
				}
			}
		}
	}
}

static块用来注册驱动

getConnection函数用来获取连接

free函数用来安全的释放资源