数据库连接工具类

package tarena.util;import java.io.InputStream;import java.sql.*;import java.util.Properties;public class DBUtil {private static final String URL;private static final String DRIVER;private static final String USERNAME;private static final String PASSWORD;static {try {Properties prop = new Properties();/** * db.properties文件保存于项目src目录下 */InputStream in = DBUtil.class.getResourceAsStream("/db.properties");prop.load(in);in.close();URL = prop.getProperty("url");DRIVER = prop.getProperty("driver");USERNAME = prop.getProperty("username");PASSWORD = prop.getProperty("password");Class.forName(DRIVER);} catch (Exception e) {e.printStackTrace();throw new RuntimeException("database connection config error!!!", e);}}public static Connection open() throws SQLException {return DriverManager.getConnection(URL, USERNAME, PASSWORD);}public static void close(ResultSet rs) {if (rs == null)return;try {rs.close();} catch (Exception e) {}}public static void close(Statement stmt) {if (stmt == null)return;try {stmt.close();} catch (Exception e) {}}public static void close(Connection con) {if (con == null)return;try {con.close();} catch (Exception e) {}}public static void close(ResultSet rs, Statement stmt) {close(rs, stmt, null);}public static void close(Statement stmt, Connection con) {close(null, stmt, con);}public static void close(ResultSet rs, Statement stmt, Connection con) {close(rs);close(stmt);close(con);}}