JDBC简易DBUtil

package jsp.utils;import java.sql.SQLException;/** * Description:数据库操作封装类 *  * Copyright: Copyright (c) 2010 *  * Company: JSP课程开发组 *  * @author zhang_jian *  * @checker *  * @version 1.0 *  * Created at 2010-10-10 *  * Modified by */public class DBUtil {//驱动程序名private String driverName;//数据库用户名private String userName;//数据库访问密码private String userPasswd;//数据库urlprivate String dburl;//数据库连接对象private java.sql.Connection conn;//数据库操作对象private java.sql.Statement stmt;//数据库查询结果集private java.sql.ResultSet rs;String databaseName = "simsdb";/** * 构造函数，初始化成员变量 *  */public DBUtil() {driverName = "com.mysql.jdbc.Driver";userName = "root";userPasswd = "root";dburl = "jdbc:mysql://localhost/"+databaseName;try {//创建新实例Class.forName("com.mysql.jdbc.Driver").newInstance();} catch (InstantiationException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();}conn = null;stmt = null;rs = null;}/** * 数据库查询 *  * @param sql *            查询语句 * @return 查询结果集 */public java.sql.ResultSet dbQuery(String sql) {System.out.println("查询语句："+sql);try {if (conn == null) {conn = java.sql.DriverManager.getConnection(dburl, userName,userPasswd);}if (stmt == null) {stmt = conn.createStatement();}rs = stmt.executeQuery(sql);} catch (SQLException sqlex) {System.out.println("数据库查询异常：");sqlex.printStackTrace();} return rs;}/** * 数据库更新 *  * @param sql *            更新的sql语句 * @return 更新影响的行数 */public int dbUpdate(String sql) {int result = 0;try {if (conn == null) {conn = java.sql.DriverManager.getConnection(dburl, userName,userPasswd);}if (stmt == null) {stmt = conn.createStatement();}System.out.println("更新语句..."+sql);result = stmt.executeUpdate(sql);} catch (SQLException sqlex) {System.out.println("数据库更新异常：");sqlex.printStackTrace();} return result;}/** * 功能：释放数据库所有连接对象 *  * @param args */public void dbClose() {if (this.rs != null) {try {this.rs.close();} catch (SQLException e) {e.printStackTrace();}}if (this.stmt != null) {try {this.stmt.close();} catch (SQLException e) {e.printStackTrace();}}if (this.conn != null) {try {this.conn.close();} catch (SQLException e) {e.printStackTrace();}}}}