The previous article analyzed the Symfony2 framework source code and explored how Symfony2 completes the first half of a request. The first half can be understood as Symfony2 The framework prepares for processing requests, including container generation, caching, bundles initialization and other preparations (Symfony2 source code analysis - startup process 1). This article talks about how Symfony2 generates a Response object based on the requested data and returns the response data to the client.
Before analysis, you need to understand the event-driven mechanism of Symfony2: Symfony2 event-driven.
Closer to home, the workflow of Symfony2 requests is actually completed by the event driver of the Symfony2 kernel. The following are the kernel events defined by the Symfony2 framework:
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, $response);这个方法触发kernel.terminate事件，此时，Symfony2已经响应了客户端的请求，
</span><span>73</span> <span>//</span><span> 向客户端输出了Response对象。监听kernel.terminate事件的监听器，主要是为了完成一些耗时的操作，操作的结果不需要返回给
</span><span>74</span> <span>//</span><span> 客户端的，例如邮件发送、图片压缩等等。
</span><span>75</span> <span>//</span><span> 到这里，Symfony2的整个流程就走完了。</span>
<span>76</span> }<span>HttpKernel::filterResponse方法和</span>HttpKernel::finishRequest方法:
图2
Symfony2框架的事件分发机制的核心代码：
<span> 1</span> <span>public</span> function dispatch($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> }
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.
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。
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