PHP+MYSQL实现读写分离简单实战

<?phpclass Db{  private $res;  function __construct($sql)  {    $querystr = strtolower(trim(substr($sql,0,6)));    //如果是select，就连接slave服务器    if($querystr == 'select')    {      $res=$this->slave_select($sql);      $this->res=$res;    }    //如果不是select，就连接master服务器    else    {      $res=$this->master_change($sql);      $this->res=$res;    }  }  /**   * slave从库返回sql查询结果   * @param $sql   * @return array   */  private function slave_select($sql){    //该处只是随机获取slave节点的ip，当然，还可以采用其他算法获取slave_ip    $slave_server=$this->get_slave_ip();    $dsn="mysql/222588.html">mysql:host=$slave_server;dbname=test";    $user='root';    $pass='123456';    $dbh=new PDO($dsn, $user, $pass);    return $dbh->query($sql)->fetchAll(PDO::FETCH_ASSOC);  }  /**master主库返回sql执行结果   * @param $sql   * @return int   */  private function master_change($sql){    $master_server='192.168.33.22';    $dsn="mysql:host=$master_server;dbname=test";    $user='root';    $pass='123456';    $dbh=new PDO($dsn, $user, $pass);    return $dbh->exec($sql);  }  /**   * 随机获取slave-ip   * @return mixed   */  private function get_slave_ip(){    $slave_ips=['192.168.33.33','192.168.33.44'];    $count=count($slave_ips)-1;    $random_key=mt_rand(0,$count);    return $slave_ips[$random_key];  }  /**          * 获取结果   * @return int   */  public function get_res(){    return $this->res;  }}$sql1 = "select * from t1";$sql2 = "insert into t1 (name) values ('haha')";$sql3 = "delete from t1 where id=1";$sql4 = "update t1 set name='Jerry' where id=2";$db = new Db($sql1);//$db = new Db($sql2);//$db = new Db($sql3);//$db = new Db($sql4);var_dump($db->get_res());