单例模式:
模式:提供创建的静态方法或在构造函数中创建。常用是静态方法。
1.构造函数私有访问属性
2.静态的指向本类的指针
3.静态的创建自身的方法
以下是php中的实现,getinstall理论上应该加上线程同步,暂未写。

<span><span><?php </span><span><span>class</span><span>myclass</span>{</span><span>public</span><span>static</span><span>$mydata1</span>=<span>NULL</span>;
    <span>private</span><span><span>function</span><span>__construct</span><span>()</span>{</span><span>echo</span><span>"构造函数<br>"</span>;
    }
    <span>public</span><span>static</span><span><span>function</span><span>getinstall</span><span>()</span> {</span><span>if</span> (   <span>self</span>::<span>$mydata1</span>==<span>null</span>)
            {
                 <span>echo</span><span>"创建对象<br>"</span>;
                  <span>self</span>::<span>$mydata1</span> = <span>new</span>  myclass();
            }
            <span>return</span><span>self</span>::<span>$mydata1</span>;
    } 
    <span>public</span><span><span>function</span><span>test</span><span>()</span>
    {</span><span>echo</span><span>"hello2<br>"</span>;
    }

} 
<span>$f</span> = myclass::getinstall();
<span>$f</span>->test();

<span>$f2</span> = myclass::getinstall();
<span>$f2</span>->test();
<span>?></span></span></span>

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以上就介绍了 php入门2 单例模式，包括了方面的内容，希望对PHP教程有兴趣的朋友有所帮助。

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