php实现的支持读写分离的MySQL类

3. /**

4. * MySQL读写分离类
5. * $db_config = array(
6. * 'master' => array('host'=>'localhost:3306','user'=>'admin','passwd'=>'123456','db'=>'stat'),
7. * 'slave' => array(
8. * array('host'=>'localhost:3307','user'=>'admin','passwd'=>'123456','db'=>'stat'),
9. * array('host'=>'localhost:3308','user'=>'admin','passwd'=>'123456','db'=>'stat')
10. * )
11. * );
12. *
13. * 注释：如果slave有多个时随机连接其中的一个
14. * 最后编辑：bbs.it-home.org
15. */
16. /*
17. $db_config = array(
18. 'master' => array('host'=>'localhost:3306','user'=>'admin','passwd'=>'123456','db'=>'stat'),
19. 'slave' => array(
20. array('host'=>'localhost:3307','user'=>'admin','passwd'=>'123456','db'=>'stat'),
21. array('host'=>'localhost:3308','user'=>'admin','passwd'=>'123456','db'=>'stat')
22. )
23. );

24. $db = MySQL::getInstance('','r-w');

25. $sql = "select * from admin";

26. $rs = $db->query($sql);

27. while ($row = $db->fetch($rs)){
28. echo "uid:".$row['uid']." ".$row['userName']."
    ";
29. }

30. echo "

    ---

    ";
31. */

32. class MySQL

33. {
34. private static $_instance = null;//数据库连接实例
35. private static $_master = null;//主数据库连接实例
36. private static $_slave = null;//重数据库连接实例
38. public $_config = array();//数据库连接配置信息
39. public $_res = null;//查询实例句柄
40. public $_flag = '';//标识当前语句是在主还是重数据库上执行
41. public $_link = null;
43. /**
44. * 单实例
45. * Enter description here ...
46. * @param unknown_type $dbname
47. * @param unknown_type $mode
48. */
49. public static function & getInstance($dbname='',$mode='rw'){
50. if (is_null(self::$_instance)){
51. self::$_instance = new self();
52. self::$_instance->__getConf();
53. self::$_instance->connect($dbname,$mode);
54. }
56. return self::$_instance;
57. }

58. /**

59. * 获取数据库配置信息
60. * Enter description here ...
61. */
62. public function __getConf(){
63. global $db_config;
64. $this->_config['master'] = $db_config['master'];
65. $this->_config['slave'] = $db_config['slave'];
66. }
68. /**
69. * 数据库连接
70. * Enter description here ...
71. * @param $dbname 指定连接的数据库名，默认情况下连接配置文件的库
72. * @param $mode rw表示连接主库，r-w表示读写分离
73. */
74. public function connect($dbname='',$mode = 'rw'){
75. if($mode == 'rw'){
76. if(is_null(self::$_master)){
77. $this->_master = $this->_slave = $this->conn_master($dbname);
78. }
79. }else{
80. if(is_null(self::$_master)){
81. $this->_master = $this->conn_master($dbname);
82. }
83. if(is_null(self::$_slave)){
84. $this->_slave = $this->conn_slave($dbname);
85. }
86. }
87. }
89. /**
90. * 连接到主数据库服务器
91. * Enter description here ...
92. */
93. public function conn_master($dbname=''){
94. $_link = mysql_connect($this->_config['master']['host'],$this->_config['master']['user'],$this->_config['master']['passwd'],true) or die ("Connect ".$this->_config['master']['host']." fail.");
95. mysql_select_db(empty($dbname)?$this->_config['master']['db']:$dbname,$_link) or die(" The DB name ".$this->_config['master']['db']." is not exists.");
96. mysql_query("set names utf8",$_link);
97. return $_link;
98. }
100. /**
101. * 连接到从数据库服务器
102. * Enter description here ...
103. */
104. public function conn_slave($dbname=''){
105. $offset = rand(0,count($this->_config['slave'])-1);
106. $_link = @mysql_connect($this->_config['slave'][$offset]['host'],$this->_config['slave'][$offset]['user'],$this->_config['slave'][$offset]['passwd'],true) or die(" Connect ".$this->_config['slave'][$offset]['host']." fail.");
107. mysql_select_db(empty($dbname)?$this->_config['slave'][$offset]['db']:$dbname,$_link) or die(" The DB name ".$this->_config['slave'][$offset]['db']." is not exists.");
108. mysql_query("set names utf8",$_link);
109. return $_link;
110. }

111. /**

112. * 执行数据库查询
113. * Enter description here ...
114. * @param string $sql
115. */
116. public function query($sql,$master=true){

117. if($master == true || (substr(strtolower($sql),0,6) != 'select') && $master == false){

118. $this->_res = mysql_query($sql,$this->_master);
119. if(!$this->_res){
120. $this->_error[] = mysql_error($this->_master);
121. }
122. $this->_flag = 'master';
123. $this->_link = $this->_master;
124. } else {
125. $this->_res = mysql_query($sql,$this->_slave);
126. if(!$this->_res){
127. $this->_error[] = mysql_error($this->_slave);
128. }
129. $this->_flag = 'slave';
130. $this->_link = $this->_slave;
131. }

132. return $this->_res;

133. }
135. /**
136. * 获取单行记录
137. * Enter description here ...
138. * @param mixed $rs
139. */
140. public function get($rs=''){
141. if(empty($rs)){
142. $rs = $this->_res;
143. }
144. return mysql_fetch_row($rs);
145. }
147. /**
148. * 获取多行记录
149. * Enter description here ...
150. * @param mixed $rs
151. * @param $result_type
152. */
153. public function fetch($rs = ''){
154. if(empty($rs)){
155. $rs = $this->_res;
156. }
157. return mysql_fetch_array($rs,MYSQL_ASSOC);
158. }
160. /**
161. * 插入数据
162. * Enter description here ...
163. * @param unknown_type $sql
164. */
165. public function add($sql){
166. $rs = $this->query($sql);
167. if($rs)
168. return mysql_insert_id($this->_link);
169. return false;
170. }
172. /**
173. * 更新数据
174. * Enter description here ...
175. * @param unknown_type $sql
176. */
177. public function update($sql){
178. if(empty($sql)) return false;
179. $rs = $this->query($sql);
180. if($rs)
181. return $this->fetchNum();
182. return false;
183. }

184. /**

185. * 获取上一条语句影响的行数
186. * Enter description here ...
187. */
188. public function fetchNum(){
189. return mysql_affected_rows($this->_link);
190. }
192. /**
193. * 析构函数,释放数据库连接资源
194. * Enter description here ...
195. */
196. public function __destruct(){
197. mysql_close($this->_link);
198. }
199. }

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