DBUtils与配置文件.properties的联系

package com.itheima.util;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.ResourceBundle;public class DBUtils {private static String driverClass;private static String url;private static String username;private static String password;static{//此对象是用于加载properties文件数据的ResourceBundle rb = ResourceBundle.getBundle("dbinfo");driverClass = rb.getString("driverClass");url = rb.getString("url");username = rb.getString("username");password = rb.getString("password");try {Class.forName(driverClass);} catch (ClassNotFoundException e) {e.printStackTrace();}}//得到连接的方法public static Connection getConnection() throws Exception{return DriverManager.getConnection(url, username, password);}//关闭资源的方法public static void closeAll(ResultSet rs,Statement stmt,Connection conn){//关闭资源if(rs!=null){try {rs.close();} catch (Exception e) {e.printStackTrace();}rs = null;}if(stmt!=null){try {stmt.close();} catch (Exception e) {e.printStackTrace();}stmt = null;}if(conn!=null){try {conn.close();} catch (Exception e) {e.printStackTrace();}conn = null;}}}