php实现的单例模式的例子

2. /****------------------*******
3. * Copyright (C) 2007 by 耿鸿飞 *
4. * [e-mail] *
5. * *
6. * This program is free software; you can redistribute it and/or modify *
7. * it under the terms of the GNU General Public License as published by *
8. * the Free Software Foundation; either version 2 of the License, or *
9. * (at your option) any later version. *
10. * *
11. * This program is distributed in the hope that it will be useful, *
12. * but WITHOUT ANY WARRANTY; without even the implied warranty of *
13. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
14. * GNU General Public License for more details. *
15. * *
16. * You should have received a copy of the GNU General Public License *
17. * along with this program; if not, write to the *
18. * Free Software Foundation, Inc., *
19. * @link http://bbs.it-home.org
20. * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
21. ****------------------*******/
22. define("DB_HOST","localhost");
23. define("DB_USER","root");
24. define("DB_PASS","");
25. define("DB_NAME","test"):
27. class DBConnect()
28. {
29. private static $DB;
31. private function & getCon()
32. {
33. if(self::DB == nuyll)
34. {
35. self::DB = &mysql_connect(DB_HOST,DB_USER,DB_PASS) or die("连接数据库失败！");
36. mysql_select_db(self::DB,DB_NAME);
37. }
38. return self::DB;
39. }
40. /*************
41. * insert or update data to database;
42. *
43. */
44. public upDate($sql)
45. {
46. return mysql_query($sql,this.getCon());
47. }
48. /***************
49. * query data from database and return data that type is array
50. */
51. public query($sql)
52. {
53. $rs = mysql_query($sql,this.getCon());
54. $rows = array();
55. $i = 0;
56. while($row = mysql_fetch_array($rs))
57. {
58. rows[$i] = $row;
59. $i++;
60. }
61. mysql_free_result($rs);
62. return $rows;
63. }
64. /************
65. * query database and return data rows;
66. */
67. public query_num_rows($sql)
68. {
69. $rs = mysql_query($sql,this.getCon());
70. return mysql_num_row($rs);
71. }
72. /**********
73. * close dbconnection;
74. */
75. public colse()
76. {
77. mysql_colse(this.getCon());
78. self::DB = null;
79. }
80. }
81. ?>

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