Yii中实现主从数据库配置方法

现在Yii框架没有配置主从数据库，本人对yii增加的扩展（不修改原现的框架为基础），得写了数据库连接的方式，实现了一主多从，同时也可以连接多个不同的数据库（支持一主多从）.详细代码如下：

一、介绍一主多从的配置：

1.extensions目录下增加DbConnectionMan.php文件，代码如下：

<?php
/**
* 主数据库 写 从数据库（可多个）读
* 实现主从数据库 读写分离 主服务器无法连接 从服务器可切换写功能
* 从务器无法连接 主服务器可切换读功
* @author: pzliang QQ：327168521
* Date:2013-10-21
* */
class DbConnectionMan extends CDbConnection {

public $timeout = 10; //连接超时时间
public $markDeadSeconds = 600; //如果从数据库连接失败 600秒内不再连接
//用 cache 作为缓存全局标记
public $cacheID = 'cache';

/**
* @var array $slaves.Slave database connection(Read) config array.
* 配置符合 CDbConnection.
* @example
* 'components'=>array(
* 		'db'=>array(
* 			'connectionString'=>'mysql://<master>',
* 			'slaves'=>array(
* 				array('connectionString'=>'mysql://<slave01>'),
* 				array('connectionString'=>'mysql://<slave02>'),
* 			)
* 		)
* )
* */
public $slaves = array();

/**
*
* 从数据库状态 false 则只用主数据库
* @var bool $enableSlave
* */
public $enableSlave = true;

/**
* @var slavesWrite 紧急情况主数据库无法连接 切换从服务器（读写）.
*/
public $slavesWrite = false;

/**
* @var masterRead 紧急情况从主数据库无法连接 切换从住服务器（读写）.
*/
public $masterRead = false;

/**
* @var _slave
*/
private $_slave;

/**
* @var _disableWrite 从服务器（只读）.
*/
private $_disableWrite = true;

/**
*
* 重写 createCommand 方法,1.开启从库 2.存在从库 3.当前不处于一个事务中 4.从库读数据
* @param string $sql
* @return CDbCommand
* */
public function createCommand($sql = null) {
if ($this->enableSlave && !empty($this->slaves) && is_string($sql) && !$this->getCurrentTransaction() && self::isReadOperation($sql) && ($slave = $this->getSlave())
) {
return $slave->createCommand($sql);
} else {
if (!$this->masterRead) {
if ($this->_disableWrite && !self::isReadOperation($sql)) {

throw new CDbException("Master db server is not available now!Disallow write operation on slave server!");
}
}
return parent::createCommand($sql);
}
}

/**
* 获得从服务器连接资源
* @return CDbConnection
* */
public function getSlave() {

if (!isset($this->_slave)) {

shuffle($this->slaves);
foreach ($this->slaves as $slaveConfig) {

if ($this->_isDeadServer($slaveConfig['connectionString'])) {
continue;
}
if (!isset($slaveConfig['class']))
$slaveConfig['class'] = 'CDbConnection';

$slaveConfig['autoConnect'] = false;
try {
if ($slave = Yii::createComponent($slaveConfig)) {
Yii::app()->setComponent('dbslave', $slave);
$slave->setAttribute(PDO::ATTR_TIMEOUT, $this->timeout);
$slave->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);
$slave->setActive(true);
$this->_slave = $slave;
break;
}
} catch (Exception $e) {
$this->_markDeadServer($slaveConfig['connectionString']);
Yii::log("Slave database connection failed!\n\tConnection string:{$slaveConfig['connectionString']}", 'warning');

continue;
}
}

if (!isset($this->_slave)) {
$this->_slave = null;
$this->enableSlave = false;
}
}
return $this->_slave;
}

public function setActive($value) {
if ($value != $this->getActive()) {
if ($value) {
try {
if ($this->_isDeadServer($this->connectionString)) {
throw new CDbException('Master db server is already dead!');
}
//PDO::ATTR_TIMEOUT must set before pdo instance create
$this->setAttribute(PDO::ATTR_TIMEOUT, $this->timeout);
$this->open();
} catch (Exception $e) {
$this->_markDeadServer($this->connectionString);
$slave = $this->getSlave();
Yii::log($e->getMessage(), CLogger::LEVEL_ERROR, 'exception.CDbException');
if ($slave) {
$this->connectionString = $slave->connectionString;
$this->username = $slave->username;
$this->password = $slave->password;
if ($this->slavesWrite) {
$this->_disableWrite = false;
}
$this->open();
} else { //Slave also unavailable
if ($this->masterRead) {
$this->connectionString = $this->connectionString;
$this->username = $this->username;
$this->password = $this->password;
$this->open();
} else {
throw new CDbException(Yii::t('yii', 'CDbConnection failed to open the DB connection.'), (int) $e->getCode(), $e->errorInfo);
}
}
}
} else {
$this->close();
}
}
}

/**
* 检测读操作 sql 语句
*
* 关键字： SELECT,DECRIBE,SHOW ...
* 写操作:UPDATE,INSERT,DELETE ...
* */
public static function isReadOperation($sql) {
$sql = substr(ltrim($sql), 0, 10);
$sql = str_ireplace(array('SELECT', 'SHOW', 'DESCRIBE', 'PRAGMA'), '^O^', $sql); //^O^,magic smile
return strpos($sql, '^O^') === 0;
}

/**
* 检测从服务器是否被标记 失败.
*/
private function _isDeadServer($c) {
$cache = Yii::app()->{$this->cacheID};
if ($cache && $cache->get('DeadServer::' . $c) == 1) {
return true;
}
return false;
}

/**
* 标记失败的slaves.
*/
private function _markDeadServer($c) {
$cache = Yii::app()->{$this->cacheID};
if ($cache) {
$cache->set('DeadServer::' . $c, 1, $this->markDeadSeconds);
}
}

}

2.config/main.php加增加以下代码

//------------------------主从数据库配置开始------------------------------------

'db2'=>array(
'class'=>'application.extensions.DbConnectionMan',//扩展路径
'connectionString' => 'mysql:host=127.0.0.1;dbname=esk_eboss_db',//主数据库 写
'emulatePrepare' => true,
'username' => 'root',
'password' => 'root',
'charset' => 'utf8',
'tablePrefix' => 'eboss_', //表前缀
'enableSlave'=>true,//从数据库启用
'slavesWrite'=>false,//紧急情况 主数据库无法连接 启用从数据库 写功能
'masterRead'=>true,//紧急情况 从数据库无法连接 启用主数据库 读功能
'enableProfiling'=>true,
'slaves'=>array(//从数据库 读
array(//slave1
'connectionString'=>'mysql:host=localhost;dbname=test',
'emulatePrepare' => true,
'username'=>'root',
'password'=>'root',
'charset' => 'utf8',
'enableProfiling'=>true,
//'tablePrefix' => 'xcpt_', //表前缀
),
array(//slave2
'connectionString'=>'mysql:host=localhost;dbname=yg_eboss_db',
'emulatePrepare' => true,
'username'=>'root',
'password'=>'root',
'charset' => 'utf8',
'enableProfiling'=>true,
//'tablePrefix' => 'xcpt_', //表前缀
),
),
),

以上是配置一主多从的配置，欢迎指正！

二、配置同时连接多个不同的数据库（支持一主多从的方式）：

1.components目录下创建ActiveRecord.php文件 代码如下：

<?php
class ActiveRecord extends CActiveRecord
{
public function getDbConnection() {
if(self::$db!==null) {
return self::$db;
} else {
self::$db=Yii::app()->getComponent('db2');//这里是我们要修改的 db2就是另一个数据库
//self::$db=Yii::app()->db1;
if(self::$db instanceof CDbConnection)
return self::$db;
else
throw new CDbException(Yii::t('yii','Active Record requires a "db2" CDbConnection application component.'));
}
}
}

2.配置连接db2配置 把上面config.php中的 db的配置复制一份 同时把db 修改成db2就可以了！

3.在model创建 Category.php（只是示例，模型名称大家可以随意定的哦）  代码如下：

<?php
/* *
* @类别表模型 eboss_cate
* @author pzliang QQ:327168521
* @CreateDate 2014-02-18
*/

class Category extends ActiveRecord  //一下要继承components目录下的ActiveRecord.php这个文件中的类哦
{
public static function model($className = __CLASS__)
{
return parent::model($className);
}

public function tableName()
{
return "{{cate}}";
}

public function rules()
{
return array(
array('cat_name,root_id,ts','required')
);
}
}

4.控制器中的调用方式是：

$info = Category::model()->find();