ThinkPHP3.2 扩展

之前写到TP3.1的行为扩展是tag();在TP3.2中引入了另一种说法—：钩子。 我们来看一下TP3.2中的钩子这个东西： 一：文件流程： 1:/index.php - require './ThinkPHP/ThinkPHP.php'; 2:/ThinkPHP/ThinkPHP.php—- require CORE_PATH.'Think'.EXT; Think\Think:

之前写到TP3.1的行为扩展是tag();在TP3.2中引入了另一种说法—：钩子。
我们来看一下TP3.2中的钩子这个东西：
一：文件流程：
1:/index.php ->require './ThinkPHP/ThinkPHP.php';
2:/ThinkPHP/ThinkPHP.php—->require CORE_PATH.'Think'.EXT; Think\Think::start();
3:/ThinkPHP/Library/Think/Think.class.php—–>App::run();
4:/ThinkPHP/Library/Think/App.class.php 。到这里基本流程就走完了，（这里不说细节）；

二：代码：
1：看一下 App::run()方法：

<code>        
        Hook<span>::listen(<span>'app_init'</span>);</span>
        App<span>::init();</span>
        
        Hook<span>::listen(<span>'app_begin'</span>);</span>
        <span>// Session初始化</span>
        <span>if(!IS_CLI)</span>{
            <span>session(<span>C(<span>'SESSION_OPTIONS'</span>)</span>)</span>;
        }
        <span>// 记录应用初始化时间</span>
        <span>G(<span>'initTime'</span>)</span>;
        App<span>::exec();</span>
        
        Hook<span>::listen(<span>'app_end'</span>);</span>
        return ;</code>

其中的Hook::listen(”)就是用来执行钩子的，我们可以在app_init这个安插的位置用来获取应用中安装的插件。

看一下Hook::listen()；

<code><span><span> @param</span><span> @param</span> mixed $params 传入参数
     *<span> @return</span> void
     */</span>
    <span>static</span> <span>public</span> <span><span>function</span> <span>listen</span><span>(<span>$tag</span>, &<span>$params</span>=NULL)</span> {</span>
        <span>if</span>(<span>isset</span>(<span>self</span>::<span>$tags</span>[<span>$tag</span>])) {
            <span>if</span>(APP_DEBUG) {
                G(<span>$tag</span>.<span>'Start'</span>);
                trace(<span>'[ '</span>.<span>$tag</span>.<span>' ] --START--'</span>,<span>''</span>,<span>'INFO'</span>);
            }
            <span>foreach</span> (<span>self</span>::<span>$tags</span>[<span>$tag</span>] <span>as</span> <span>$name</span>) {
                APP_DEBUG && G(<span>$name</span>.<span>'_start'</span>);
                <span>$result</span> =   <span>self</span>::exec(<span>$name</span>, <span>$tag</span>,<span>$params</span>);
                <span>if</span>(APP_DEBUG){
                    G(<span>$name</span>.<span>'_end'</span>);
                    trace(<span>'Run '</span>.<span>$name</span>.<span>' [ RunTime:'</span>.G(<span>$name</span>.<span>'_start'</span>,<span>$name</span>.<span>'_end'</span>,<span>6</span>).<span>'s ]'</span>,<span>''</span>,<span>'INFO'</span>);
                }
                <span>if</span>(<span>false</span> === <span>$result</span>) {
                    <span>// 如果返回false 则中断插件执行</span>
                    <span>return</span> ;
                }
            }
            <span>if</span>(APP_DEBUG) { <span>// 记录行为的执行日志</span>
                trace(<span>'[ '</span>.<span>$tag</span>.<span>' ] --END-- [ RunTime:'</span>.G(<span>$tag</span>.<span>'Start'</span>,<span>$tag</span>.<span>'End'</span>,<span>6</span>).<span>'s ]'</span>,<span>''</span>,<span>'INFO'</span>);
            }
        }
        <span>return</span>;
    }</code>

其中关键是：self::exec($name, $tag,$params); 看一下exec的代码：

<code> <span>/**
     * 执行某个插件
     *<span> @param</span> string $name 插件名称
     *<span> @param</span><span> @param</span> Mixed $params 传入的参数
     *<span> @return</span> void
     */</span>
    <span>static</span> <span>public</span> <span><span>function</span> <span>exec</span><span>(<span>$name</span>, <span>$tag</span>,&<span>$params</span>=NULL)</span> {</span>
        <span>if</span>(<span>false</span> === strpos(<span>$name</span>,<span>'\\'</span>)) {
            <span>// 插件（多个入口）</span>
            <span>$class</span>   =  <span>"Addons\\{$name}\\{$name}Addon"</span>;
        }<span>else</span>{
            <span>// 行为扩展（只有一个run入口方法）</span>
            <span>$class</span>   =  <span>$name</span>.<span>'Behavior'</span>;
            <span>$tag</span>    =   <span>'run'</span>;
        }
        <span>$addon</span>   = <span>new</span> <span>$class</span>();
        <span>return</span> <span>$addon</span>-><span>$tag</span>(<span>$params</span>);
    }</code>

最后还不是 new $class();进而return $addon->$tag($params); 又转到了具体钩子的代码方法。其实就是我们原本的调用class的方法，只不过经过别人的高度封装了。

三：那么问题来了，这个钩子有什么用呢？ 怎么用？
这里以OneThink 的{:hook('AdminIndex')}为例，看一些别人是怎么用的。
在系统初始化到 Hook::listen('app_init'); 时，

<code><span><span><?php </span>
<span>return</span> <span>array</span>(
    <span>'app_init'</span>=><span>array</span>(<span>'Common\Behavior\InitHook'</span>)
);</span></span></code>

一看就明白，无非就是读取持久化的信息，放到缓存或是其他的方式

<code> <span>// 行为扩展的执行入口必须是run</span>
    <span>public</span> <span><span>function</span> <span>run</span><span>(&<span>$content</span>)</span>{</span>
        <span>if</span>(<span>isset</span>(<span>$_GET</span>[<span>'m'</span>]) && <span>$_GET</span>[<span>'m'</span>] === <span>'Install'</span>) <span>return</span>;

        <span>$data</span> = S(<span>'hooks'</span>);
        <span>if</span>(!<span>$data</span>){
            <span>$hooks</span> = M(<span>'Hooks'</span>)->getField(<span>'name,addons'</span>);
            <span>foreach</span> (<span>$hooks</span> <span>as</span> <span>$key</span> => <span>$value</span>) {
                <span>if</span>(<span>$value</span>){
                    <span>$map</span>[<span>'status'</span>]  =   <span>1</span>;
                    <span>$names</span>          =   explode(<span>','</span>,<span>$value</span>);
                    <span>$map</span>[<span>'name'</span>]    =   <span>array</span>(<span>'IN'</span>,<span>$names</span>);
                    <span>$data</span> = M(<span>'Addons'</span>)->where(<span>$map</span>)->getField(<span>'id,name'</span>);
                    <span>if</span>(<span>$data</span>){
                        <span>$addons</span> = array_intersect(<span>$names</span>, <span>$data</span>);
                        Hook::add(<span>$key</span>,<span>$addons</span>);
                    }
                }
            }
            S(<span>'hooks'</span>,Hook::get());
        }<span>else</span>{
            Hook::import(<span>$data</span>,<span>false</span>);
        }
    }</code>

当在程序执行到{:hook(‘AdminIndex’)}时—>调用的是Hook::listen(‘AdminIndex’);
AdminIndex这个挂载点包含了三个插件：分别是：SiteStat， SystemInfo，DevTeam。
用一个循环来分别按顺序执行.

总结：钩子其实就是起到一个挂载点的作用，这个钩子挂在哪里，就可以在哪里执行，内容或功能就是挂载插件或类库的具体实现。这样实现的代码就有很大的灵活性，挂载点不变，挂的东西变量，功能也就相应的变化，是不是很灵活强大呀。

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