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php __call方法使用说明

Jun 13, 2016 am 10:04 AM
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本文章来给大家介绍php __call方法使用说明,有需要学习php __call方法的朋友不防进入参考。 相信刚开始接触PHP的童鞋都,在参考书上看到过__call这个魔法方法,而且也看到了它的应用实例!但是,等你真的开始写代码的时候,你用过它吗!?说实话,我用PHP也有一段时间了,但真的从没将它应用到实际开发中。

先说一下__call 的作用吧:"PHP5 对象新增的一个专用方法 ,这个方法用来监视一个对象中的其它方法。如果你试着调用一个对象中不存在的方法,__call 方法将会被自动调用。"

典型用例:

 代码如下 复制代码
runTest('in object context');

 
运行结果:
Calling object method 'runTest' in object context
不过,最近终于看到了一个__call在实际开发中的应用。thinkphp作为国内应用比较普遍的框架,在它里面对这个方法应用个人觉得算的上是完美啊!

比如在thinkphp的:lib->think->core->model.class.php文件里面(Model类)有这么一段代码:

 代码如下 复制代码
    /**
     +----------------------------------------------------------
     * 利用__call方法实现一些特殊的Model方法
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param string $method 方法名称
     * @param array $args 调用参数
     +----------------------------------------------------------
     * @return mixed
     +----------------------------------------------------------
     */
    public function __call($method,$args) {
        if(in_array(strtolower($method),array('field','table','where','order','limit','page','alias','having','group','lock','distinct'),true)) {
            // 连贯操作的实现
            $this->options[strtolower($method)] =   $args[0];
            return $this;
        }elseif(in_array(strtolower($method),array('count','sum','min','max','avg'),true)){
            // 统计查询的实现
            $field =  isset($args[0])?$args[0]:'*';
            return $this->getField(strtoupper($method).'('.$field.') AS tp_'.$method);
        }elseif(strtolower(substr($method,0,5))=='getby') {
            // 根据某个字段获取记录
            $field   =   parse_name(substr($method,5));
            $where[$field] =  $args[0];
            return $this->where($where)->find();
        }else{
            throw_exception(__CLASS__.':'.$method.L('_METHOD_NOT_EXIST_'));
            return;
        }
    }

代码的具体功能,我就不解释了,第一可能我也解释不清楚;第二自己去看一下里面的编程思想还是有很多值的学习的。

说一下他的调用方法,就能看出他的"强大"了。
调用:
$this->dao= M('table');          //快速高性能实例化一个 table 表的模型
$this->dao->field($field)->where($where)->limit($offset . ',' . $limit)->select();    //设置查询字段,查询条件,设置查询数量,最后执行查询操作。当然返回的就是数据库记录了

看到"不对劲"了吧,field方法成对象了,where、limit、select方法也成对象了,其实field、where这些方法在 Model类 里面都不存在。正是因为这些方法不存在,所以这个时候__call方法被执行了,然后又会返回$this对象。所以可以实现这种"衔接"写法,一行代码搞了所有的SQL语句。

不再说下去了,就是向大家介绍一个__call方法的实际应用。要想完全理解它还是建议你自己去看thinkphp的源码吧!(申明:本人跟thinkphp没有任何关系,并不是在鼓吹它的好)

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