magento 提交搜索按钮后执行的代码如下：

<?php
/**
 * Catalog Search Controller
 */
class Mage_CatalogSearch_ResultController extends Mage_Core_Controller_Front_Action
{
    /**
     * Retrieve catalog session
     *
     * @return Mage_Catalog_Model_Session
     */
    protected function _getSession()
    {
        return Mage::getSingleton('catalog/session');
    }
    /**
     * Display search result
     */
    public function indexAction()
    {
        $query = Mage::helper('catalogsearch')->getQuery();
        /* @var $query Mage_CatalogSearch_Model_Query */

        $query->setStoreId(Mage::app()->getStore()->getId());

        if ($query->getQueryText() != '') {
            if (Mage::helper('catalogsearch')->isMinQueryLength()) {
                $query->setId(0)
                    ->setIsActive(1)
                    ->setIsProcessed(1);
            }
            else {
                if ($query->getId()) {
                    $query->setPopularity($query->getPopularity()+1);
                }
                else {
                    $query->setPopularity(1);
                }

                if ($query->getRedirect()){
                    $query->save();
                    $this->getResponse()->setRedirect($query->getRedirect());
                    return;
                }
                else {
                    $query->prepare();
                }
            }

            Mage::helper('catalogsearch')->checkNotes();

            $this->loadLayout();
            $this->_initLayoutMessages('catalog/session');
            $this->_initLayoutMessages('checkout/session');
            $this->renderLayout();

            if (!Mage::helper('catalogsearch')->isMinQueryLength()) {
                $query->save();
            }
        }
        else {
            $this->_redirectReferer();
        }
    }
}

1、关键字提交到系统的catalogsearch/result/index控制器，在控制器的$this->loadLayout();前，所有的代码都是判断关键字是否有人用过，用过就热度加1，没用过就把关键字存入数据库，同时还包括关键字的长度个数判断，但是在$this->loadLayout();之前并没有对产品作任何过滤工作，只是单存的把关键字存入数据库而已。

2、$this->loadLayout();在这个过程中，系统加载当前控制器的布局配置文件并初始化相应的Block我的例子中catalogsearch/result/index对应的布局配置如下

<catalogsearch_result_index translate="label">
    <label>Quick Search Form</label>
    <reference name="root">
        <action method="setTemplate"><template>page/2columns-left.phtml</template></action>
    </reference>
    <reference name="left_first">
        <block type="catalogsearch/layer" name="catalogsearch.leftnav" after="currency" template="catalog/layer/view.phtml">
            <block type="core/text_list" name="catalog.leftnav.state.renderers" as="state_renderers" />
        </block>
    </reference>
    <reference name="content">
        <block type="catalogsearch/result" name="search.result" template="catalogsearch/result.phtml">
            <block type="catalog/product_list" name="search_result_list" template="catalog/product/list.phtml">
                <block type="core/text_list" name="product_list.name.after" as="name.after" />
                <block type="core/text_list" name="product_list.after" as="after" />
                <block type="catalog/product_list_toolbar" name="product_list_toolbar" template="catalog/product/list/toolbar.phtml">
                    <block type="page/html_pager" name="product_list_toolbar_pager"/>
                </block>
                <action method="addColumnCountLayoutDepend"><layout>empty</layout><count>6</count></action>
                <action method="addColumnCountLayoutDepend"><layout>one_column</layout><count>5</count></action>
                <action method="addColumnCountLayoutDepend"><layout>two_columns_left</layout><count>4</count></action>
                <action method="addColumnCountLayoutDepend"><layout>two_columns_right</layout><count>4</count></action>
                <action method="addColumnCountLayoutDepend"><layout>three_columns</layout><count>3</count></action>
                <action method="setToolbarBlockName"><name>product_list_toolbar</name></action>
                <action method="setColumnCount"><count>4</count></action>
            </block>
            <action method="setListOrders"/>
            <action method="setListModes"/>
            <action method="setListCollection"/>
        </block>
    </reference>
</catalogsearch_result_index>

3、上面配置中的粗体部分是使搜索功能有效的关键所在，解释如下因为有了红色部分的配置，系统会初始化类Mage_CatalogSearch_Block_Layer，初始化的过程如下

 
protected function _construct()
{
 parent::_construct();

 Mage::register('current_layer', $this->getLayer(), true);//这里会注册一个全局变量current_layer,并把类
Mage_CatalogSearch_Model_Layer的实例付给它
 
}
public function getLayer()
{
 return Mage::getSingleton('catalogsearch/layer');
} 

4、在catalog/product/list.phtml中会调用对应的block类Mage_Catalog_Block_Product_List中的方法getLoadedProductCollection(),而最终会调用该类的方法getLayer()获取上面定义的全局变量current_layer，并调用current_layer的getProductCollection()获取用关键字过滤过的产品集合作为最终搜索结果

 public function getLayer()
{  
 $layer = Mage::registry('current_layer');

 if ($layer) {

 return $layer;

 }
  
 return Mage::getSingleton('catalog/layer');
 
}