Symfony2源码分析——启动过程2，symfony2源码

　　上一篇分析Symfony2框架源码，探究Symfony2如何完成一个请求的前半部分，前半部分可以理解为Symfony2框架为处理请求做准备工作，包括container生成、缓存、bundls初始化等一些列准备工作（Symfony2源码分析——启动过程1）。而这一篇讲的是Symfony2如何根据请求的数据生成Response对象，向客户端返回响应数据。

　　在分析前需要了解Symfony2的事件驱动机制：Symfony2事件驱动。

　　言归正传，Symfony2请求的工作流程其实是Symfony2内核的事件驱动完成的，下面是Symfony2框架定义好的内核事件：

final class KernelEvents { /** * The REQUEST event occurs at the very beginning of request * dispatching * * This event allows you to create a response for a request before any * other code in the framework is executed. The event listener method * receives a Symfony\Component\HttpKernel\Event\GetResponseEvent * instance. * * @var string * * @api */ const REQUEST = 'kernel.request'; /** * The EXCEPTION event occurs when an uncaught exception appears * * This event allows you to create a response for a thrown exception or * to modify the thrown exception. The event listener method receives * a Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent * instance. * * @var string * * @api */ const EXCEPTION = 'kernel.exception'; /** * The VIEW event occurs when the return value of a controller * is not a Response instance * * This event allows you to create a response for the return value of the * controller. The event listener method receives a * Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent * instance. * * @var string * * @api */ const VIEW = 'kernel.view'; /** * The CONTROLLER event occurs once a controller was found for * handling a request * * This event allows you to change the controller that will handle the * request. The event listener method receives a * Symfony\Component\HttpKernel\Event\FilterControllerEvent instance. * * @var string * * @api */ const CONTROLLER = 'kernel.controller'; /** * The RESPONSE event occurs once a response was created for * replying to a request * * This event allows you to modify or replace the response that will be * replied. The event listener method receives a * Symfony\Component\HttpKernel\Event\FilterResponseEvent instance. * * @var string * * @api */ const RESPONSE = 'kernel.response'; /** * The TERMINATE event occurs once a response was sent * * This event allows you to run expensive post-response jobs. * The event listener method receives a * Symfony\Component\HttpKernel\Event\PostResponseEvent instance. * * @var string */ const TERMINATE = 'kernel.terminate'; /** * The FINISH_REQUEST event occurs when a response was generated for a request. * * This event allows you to reset the global and environmental state of * the application, when it was changed during the request. * * @var string */ const FINISH_REQUEST = 'kernel.finish_request'; } View Code

　　我们可以编写事件监听器，监听相应的内核事件，在Symfony2触发该事件的时候，相应的事件监听器就会执行。监听和唤醒形象的描述，就像，你（事件监听器）参加校运会，去大会（Symfony2）登记（监听）参加50米短跑（事件），当50米短跑比赛开始了（事件被触发），那你就奔跑吧（监听器执行，其实就是一个执行函数，函数完成什么工作就取决于你的需求了），少年。

　　Symfony2的内核事件处理流程大部分工作都在HttpKernel::handleRaw方法中：

<span> 1</span>     <span>private</span> function handleRaw(Request $request, $type =<span> self::MASTER_REQUEST)
</span><span> 2</span> <span>    {
</span><span> 3</span>         $<span>this</span>->requestStack-><span>push($request);
</span><span> 4</span> 
<span> 5</span>         <span>//</span><span> request
</span><span> 6</span>         <span>//</span><span> 初始化事件，事件对象会被传递给监听器，所以事件可以说是一个信息的载体，事件内存放着监听器感兴趣的数据。</span>
<span> 7</span>         $<span>event</span> = <span>new</span> GetResponseEvent($<span>this</span><span>, $request, $type);
</span><span> 8</span>         <span>//</span><span> 触发kernel.request事件，后续详细讲解EventDispatcher::dispatch方法的实现，
</span><span> 9</span>         <span>//</span><span> 这里我们需要知道的是，dispatcher把$event传递给所有监听了kernel.request事件的监听器，监听器将会执行。
</span><span>10</span>         <span>//</span><span> kernel.request事件发生在controller执行之前，我们可以在这一步奏完成路由解析等为controller执行提供准备数据，
</span><span>11</span>         <span>//</span><span> 在这个过程允许我们直接生成Response对象，向客户端输出数据，那么controller就不会被执行了。</span>
<span>12</span>         $<span>this</span>->dispatcher->dispatch(KernelEvents::REQUEST, $<span>event</span><span>);
</span><span>13</span> 
<span>14</span>         <span>//</span><span> 如果我们在kernel.request事件生成了Response对象（响应数据），那么就跳过kernel.controller、kernel.view事件、
</span><span>15</span>         <span>//</span><span> controller也会被跳过，直接执行kernel.response事件。</span>
<span>16</span>         <span>if</span> ($<span>event</span>-><span>hasResponse()) {
</span><span>17</span>             <span>return</span> $<span>this</span>->filterResponse($<span>event</span>-><span>getResponse(), $request, $type);
</span><span>18</span> <span>        }
</span><span>19</span> 
<span>20</span>         <span>//</span><span> load controller
</span><span>21</span>         <span>//</span><span> 根据路由规则返回 一个对象或者数组或者字符串 ，如果$controller是一个数组，$controller[0]是存放的是要执行的controller对象，
</span><span>22</span>         <span>//</span><span> $controller[0]存放的是controller对象执行的方法，即action，方法的参数没有保存在$controller数组中；
</span><span>23</span>         <span>//</span><span> 如果$controller是对象，那么该对象就实现了__invoke 方法；
</span><span>24</span>         <span>//</span><span> 如果$controller是字符串，那么$controller就是要运行的函数的函数名。
</span><span>25</span>         <span>//</span><span> 图2是$controller的一个var_dump例子</span>
<span>26</span>         <span>if</span> (<span>false</span> === $controller = $<span>this</span>->resolver-><span>getController($request)) {
</span><span>27</span>             <span>throw</span> <span>new</span> NotFoundHttpException(sprintf(<span>'</span><span>Unable to find the controller for path "%s". Maybe you forgot to add the matching route in your routing configuration?</span><span>'</span>, $request-><span>getPathInfo()));
</span><span>28</span> <span>        }
</span><span>29</span> 
<span>30</span>         $<span>event</span> = <span>new</span> FilterControllerEvent($<span>this</span><span>, $controller, $request, $type);
</span><span>31</span>         <span>//</span><span> 触发kernel.controller事件，这个事件发生在controller执行前。我们可以通过监听这个事件在controller执行前修改controller，
</span><span>32</span>         <span>//</span><span> 或者完成一些动作。</span>
<span>33</span>         $<span>this</span>->dispatcher->dispatch(KernelEvents::CONTROLLER, $<span>event</span><span>);
</span><span>34</span>         $controller = $<span>event</span>-><span>getController();
</span><span>35</span> 
<span>36</span>         <span>//</span><span> controller arguments
</span><span>37</span>         <span>//</span><span> 从request对象中获取controller方法的参数</span>
<span>38</span>         $arguments = $<span>this</span>->resolver-><span>getArguments($request, $controller);
</span><span>39</span> 
<span>40</span>         <span>//</span><span> call controller
</span><span>41</span>         <span>//</span><span> 执行controller</span>
<span>42</span>         $response =<span> call_user_func_array($controller, $arguments);
</span><span>43</span> 
<span>44</span>         <span>//</span><span> view
</span><span>45</span>         <span>//</span><span> 如果$response不是Response对象，那么kernel.view事件就会触发，监听kernel.view事件的监听器通过$response值生成Response对象。</span>
<span>46</span>         <span>if</span> (!<span>$response instanceof Response) {
</span><span>47</span>             $<span>event</span> = <span>new</span> GetResponseForControllerResultEvent($<span>this</span><span>, $request, $type, $response);
</span><span>48</span>             $<span>this</span>->dispatcher->dispatch(KernelEvents::VIEW, $<span>event</span><span>);
</span><span>49</span> 
<span>50</span>             <span>if</span> ($<span>event</span>-><span>hasResponse()) {
</span><span>51</span>                 $response = $<span>event</span>-><span>getResponse();
</span><span>52</span> <span>            }
</span><span>53</span> 
<span>54</span>             <span>if</span> (!<span>$response instanceof Response) {
</span><span>55</span>                 $msg = sprintf(<span>'</span><span>The controller must return a response (%s given).</span><span>'</span>, $<span>this</span>-><span>varToString($response));
</span><span>56</span> 
<span>57</span>                 <span>//</span><span> the user may have forgotten to return something</span>
<span>58</span>                 <span>if</span> (<span>null</span> ===<span> $response) {
</span><span>59</span>                     $msg .= <span>'</span><span> Did you forget to add a return statement somewhere in your controller?</span><span>'</span><span>;
</span><span>60</span> <span>                }
</span><span>61</span>                 <span>throw</span> <span>new</span><span> \LogicException($msg);
</span><span>62</span> <span>            }
</span><span>63</span> <span>        }
</span><span>64</span> 
<span>65</span>         <span>//</span><span> 触发kernel.response事件，在向客户端输出Response对象前，我们可以对Response对象进行修改，
</span><span>66</span>         <span>//</span><span> 例如修改response头部，设置缓存、压缩输出数据等。
</span><span>67</span> 
<span>68</span>         <span>//</span><span> 接着触发kernel.finish_request事件，把当前请求从请求栈中弹出，当前请求就完成。</span>
<span>69</span>         <span>return</span> $<span>this</span>-><span>filterResponse($response, $request, $type);
</span><span>70</span> 
<span>71</span>         <span>//</span><span> 千万别忘记了，filterResponse执行完后，Symfony2内核事件处理流程还有最后一步，位于app_dev.php[app.php]最后一行，
</span><span>72</span>         <span>//</span><span> $kernel->terminate($request, $response);这个方法触发kernel.terminate事件，此时，Symfony2已经响应了客户端的请求，
</span><span>73</span>         <span>//</span><span> 向客户端输出了Response对象。监听kernel.terminate事件的监听器，主要是为了完成一些耗时的操作，操作的结果不需要返回给
</span><span>74</span>         <span>//</span><span> 客户端的，例如邮件发送、图片压缩等等。
</span><span>75</span>         <span>//</span><span> 到这里，Symfony2的整个流程就走完了。</span>
<span>76</span>     }

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<span>HttpKernel::filterResponse方法和</span>HttpKernel::finishRequest方法:

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1 private function filterResponse(Response $response, Request $request, $type) 2 { 3 $event = new FilterResponseEvent($this, $request, $type, $response); 4 5 $this->dispatcher->dispatch(KernelEvents::RESPONSE, $event); 6 7 $this->finishRequest($request, $type); 8 9 return $event->getResponse(); 10 } 11 12 /** 13 * Publishes the finish request event, then pop the request from the stack. 14 * 15 * Note that the order of the operations is important here, otherwise 16 * operations such as {@link RequestStack::getParentRequest()} can lead to 17 * weird results. 18 * 19 * @param Request $request 20 * @param int $type 21 */ 22 private function finishRequest(Request $request, $type) 23 { 24 $this->dispatcher->dispatch(KernelEvents::FINISH_REQUEST, new FinishRequestEvent($this, $request, $type)); 25 $this->requestStack->pop(); 26 } View Code

图2

Symfony2框架的事件分发机制的核心代码：

<span> 1</span>     <span>public</span> function dispatch($eventName, Event $<span>event</span> = <span>null</span><span>)
</span><span> 2</span> <span>    {
</span><span> 3</span>         <span>if</span> (<span>null</span> === $<span>event</span><span>) {
</span><span> 4</span>             $<span>event</span> = <span>new</span><span> Event();
</span><span> 5</span> <span>        }
</span><span> 6</span> 
<span> 7</span>         $<span>event</span>->setDispatcher($<span>this</span><span>);
</span><span> 8</span>         $<span>event</span>-><span>setName($eventName);
</span><span> 9</span> 
<span>10</span>         <span>if</span> (!isset($<span>this</span>-><span>listeners[$eventName])) {
</span><span>11</span>             <span>return</span> $<span>event</span><span>;
</span><span>12</span> <span>        }
</span><span>13</span> 
<span>14</span>         <span>//</span><span> $eventName即：KernelEvents::REQUEST、KernelEvents::CONTROLLER、KernelEvents::VIEW、KernelEvents::RESPONSE、KernelEvents::TERMINATE等
</span><span>15</span>         <span>//</span><span> getListeners返回所有监听$eventName事件的监听器</span>
<span>16</span>         $<span>this</span>->doDispatch($<span>this</span>->getListeners($eventName), $eventName, $<span>event</span><span>);
</span><span>17</span> 
<span>18</span>         <span>return</span> $<span>event</span><span>;
</span><span>19</span> <span>    }
</span><span>20</span> 
<span>21</span>     <span>protected</span> function doDispatch($listeners, $eventName, Event $<span>event</span><span>)
</span><span>22</span> <span>    {
</span><span>23</span>         <span>//</span><span> 监听器执行</span>
<span>24</span>         <span>foreach</span> ($listeners <span>as</span><span> $listener) {
</span><span>25</span>             call_user_func($listener, $<span>event</span>, $eventName, $<span>this</span><span>);
</span><span>26</span>             <span>//</span><span> 如果其中一个监听器把$event的propagationStopped属性设置为true，那么表示$eventName这一事件终止执行，
</span><span>27</span>             <span>//</span><span> 事件不会往$listeners里尚未执行的监听器传递该事件。</span>
<span>28</span>             <span>if</span> ($<span>event</span>-><span>isPropagationStopped()) {
</span><span>29</span>                 <span>break</span><span>;
</span><span>30</span> <span>            }
</span><span>31</span> <span>        }
</span><span>32</span>     }

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有没有哪本书具体讲linux内核启动过程的，详细点的（最好具体到实际代码），最好内核针对于26以后的

我个人感觉毛德操先生的书linux内核情景分析,分析的很透彻的,对整个Linux内核的讲解很不错.具体到启动过程,这个启动过程很泛的,你只需要知道整体的启动过程,其他的细节,还得看内核源码讲解,所以,推荐你看点博客了解下启动大体过程,具体到每个细节,看linux内核情景分析吧.

android 21的源码分析之长按电源键弹出对话框功可以更改

1.这个dialog是由PhoneWindowManager控制的，在PhoneWindowManager的interceptKeyTq方法中，代码是这一行

mHandler.postDelayed(mPowerLongPress, ViewConfiguration.getGlobalActionKeyTimeout());

mProwerLongPress是一个Runnable，执行时调用GlobalActions中的showDialog方法。所以这个dialog是由GlobalActions管理的，PowerDialog是之前版本中的，现在已经弃用了。

2.可以在GlobalActions中createDialog方法中mSilentModeToggle action的onToggle方法中加入

mAudioManager.setVibrateSetting(AudioManager.VIBRATE_TYPE_RINGER, on ? AudioManager.VIBRATE_SETTING_ON : AudioManager.VIBRATE_SETTING_OFF);

这一句，仿照铃声的处理，应该没问题，不过没试所以也不能确定。

希望对你有帮助。