一、单例模式，示例：
<?php
class Predis{
public $redis = "";
private static $_instance = null;
public static function getInstance() {
if(empty(self::$_instance)) {
self::$_instance = new self();
}
return self::$_instance;
}
private function __construct() {
$this->redis = new \Redis();
$result = $this->redis->connect(config(‘redis.host‘), config(‘redis.port‘), config(‘redis.timeOut‘));
if($result === false) {
throw new \Exception(‘redis connect error‘);
}
}
}
原文：https://www.cnblogs.com/zhengchuzhou/p/9617279.html