import java.sql.Connection;  
    import java.sql.DriverManager;  
    import java.sql.ResultSet;  
    import java.sql.SQLException;  
    import java.sql.Statement;  
      
    public class DBUtil {  
        public static final String DRIVER = "com.mysql.jdbc.Driver";  
        public static final String URL = "jdbc:mysql://localhost:3306/db";  
        public static final String USERNAME = "root";  
        public static final String PASSWORD = "root";  
      
        /** 
         * 通过静态代码块 注册数据库驱动 
         */  
        static {  
            try {  
                Class.forName(DRIVER);  
            } catch (ClassNotFoundException e) {  
                e.printStackTrace();  
            }  
        }  
      
        /** 
         * 获得Connection 
         *  
         * @return 
         */  
        public static Connection getConnection() {  
            Connection conn = null;  
            try {  
                conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);  
            } catch (SQLException e) {  
                e.printStackTrace();  
            }  
            return conn;  
        }  
      
        /** 
         * 获得Statement 
         *  
         * @return 
         */  
        public static Statement getStatement() {  
            Statement st = null;  
            try {  
                st = getConnection().createStatement();  
            } catch (SQLException e) {  
                e.printStackTrace();  
            }  
            return st;  
        }  
      
        /** 
         * 关闭ResultSet 
         *  
         * @param rs 
         */  
        public static void closeResultSet(ResultSet rs) {  
            if (rs != null) {  
                try {  
                    rs.close();  
                } catch (SQLException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
      
        /** 
         * 关闭Statement 
         *  
         * @param st 
         */  
        public static void closeStatement(Statement st) {  
            if (st != null) {  
                try {  
                    st.close();  
                } catch (SQLException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
      
        /** 
         * 关闭Connection 
         *  
         * @param conn 
         */  
        public static void closeConnection(Connection conn) {  
            if (conn != null) {  
                try {  
                    conn.close();  
                } catch (SQLException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
      
        /** 
         * 关闭全部 
         *  
         * @param rs 
         * @param sta 
         * @param conn 
         */  
        public static void closeAll(ResultSet rs, Statement sta, Connection conn) {  
            closeResultSet(rs);  
            closeStatement(sta);  
            closeConnection(conn);  
        }  
      
    }