jdbc 简单工具类的使用

package Jdbcday02;import java.io.IOException;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.Properties;public class ConnectionUtils {private static String url;private static String driver;private static String username;private static String password;static {Properties props = new Properties();try {props.load(ConnectionUtils.class.getClassLoader().getResourceAsStream("Jdbcday02/db_oracle.properties"));} catch (IOException e) {}if (props != null) {url = props.getProperty("url");driver = props.getProperty("driver");username = props.getProperty("username");password = props.getProperty("password");try {Class.forName(driver);} catch (ClassNotFoundException e) {}}}public static Connection openConnection() throws SQLException {return DriverManager.getConnection(url, username, password);}public static void closeConnection(Connection con) {try {if (con != null) {con.close();}} catch (SQLException e) {}}public static void closeStatement(Statement stmt) {try {if (stmt != null) {stmt.close();}} catch (SQLException e) {}}public static void closeStatement(PreparedStatement pstmt) {try {if (pstmt != null) {pstmt.close();}} catch (SQLException e) {}}public static void closeResultSet(ResultSet rs) {try {if (rs != null) {rs.close();}} catch (SQLException e) {}}}