28.3. 视图脚本
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## 28.3. 视图脚本

一旦你的Controller已经完成了变量赋值和调用render()，Zend_View就会调用视图脚本并在Zend_View的实例内部执行。因此，在你的视图脚本内，$this是指向Zend_View的实例的。

从控制器传递到视图的变量以对象属性的形式来调用。如果控制器有一个变量"something" ，那么视图代码中就要用$this->something来调用。这样的作法可以让你分清哪些是来自Zend_View实例的变量，哪些是视图自身的变量。

为了说明，这里有一个例子：

    <?php if ($this->books): ?>

        <!-- A table of some books. -->
        <table>
            <tr>
                <th>Author</th>
                <th>Title</th>
            </tr>

            <?php foreach ($this->books as $key => $val): ?>
            <tr>
                <td><?php echo $this->escape($val['author']) ?></td>
                <td><?php echo $this->escape($val['title']) ?></td>
            </tr>
            <?php endforeach; ?>

        </table>

    <?php else: ?>

        <p>There are no books to display.</p>

    <?php endif; ?>

### 28.3.1. 转义输出（Escaping Output）

One of the most important tasks to perform in a view script is to make sure that output is escaped properly; among other things, this helps to avoid cross-site scripting attacks. Unless you are using a function, method, or helper that does escaping on its own, you should always escape variables when you output them. View脚本的最重要的工作之一是保证输出的内容是合适的，比如需要避免跨站攻击漏洞。除非你已经使用一个函数，类方法或协助器（helper）来转义内容，你需要在输出时对变量进行转义。

Zend_View带有一个escape()方法来提供这个功能：

    <?php
    // bad view-script practice:
    echo $this->variable;

    // good view-script practice:
    echo $this->escape($this->variable);
    ?>

默认地，escape()方法使用PHP函数htmlspecialchars()来过滤，但你也可以通过setEscape()方法来在Controller内告诉Zend_View需要怎么过滤。

    <?php
    // create a Zend_View instance
    $view = new Zend_View();

    // tell it to use htmlentities as the escaping callback
    $view->setEscape('htmlentities');

    // or tell it to use a static class method as the callback
    $view->setEscape(array('SomeClass', 'methodName'));

    // or even an instance method
    $obj = new SomeClass();
    $view->setEscape(array($obj, 'methodName'));

    // and then render your view
    echo $view->render(...);
    ?>

The callback function or method should take the value to be escaped as its first parameter, and all other parameters should be optional. 设定的转义函数会将需要转义的变量作为其第一个参数，其它参数是可选的。

### 28.3.2. 使用模板系统

Although PHP is itself a powerful template system, many developers feel it is too powerful or complex for their template designers and will want to use an alternate template engine. Zend_View provides two mechanisms for doing so, the first through view scripts, the second by implementing Zend_View_Interface. 许多开发者觉得尽管PHP本身就是一个强大的模板系统，但对模板设计师来说，使用PHP标签过于复杂。Zend_View提供了两套机制来同时满足这两种要求，一种是直接通过通过视图脚本，另一种是实现Zend_View_Interface接口。

#### 28.3.2.1. Template Systems Using View Scripts

A view script may be used to instantiate and manipulate a separate template object, such as a PHPLIB-style template. The view script for that kind of activity might look something like this: View脚本可能要被用来初始化和操作一个其它模板对象的实例，例如PHPLIB风格的模板。这时View脚本可能是这样的：

    <?php
    include_once 'template.inc';
    $tpl = new Template();

    if ($this->books) {
        $tpl->setFile(array(
            "booklist" => "booklist.tpl",
            "eachbook" => "eachbook.tpl",
        ));

        foreach ($this->books as $key => $val) {
            $tpl->set_var('author', $this->escape($val['author']);
            $tpl->set_var('title', $this->escape($val['title']);
            $tpl->parse("books", "eachbook", true);
        }

        $tpl->pparse("output", "booklist");
    } else {
        $tpl->setFile("nobooks", "nobooks.tpl")
        $tpl->pparse("output", "nobooks");
    }
    ?>

下面是相关的模板文件：

    <!-- booklist.tpl -->
    <table>
        <tr>
            <th>Author</th>
            <th>Title</th>
        </tr>
        {books}
    </table>

    <!-- eachbook.tpl -->
        <tr>
            <td>{author}</td>
            <td>{title}</td>
        </tr>

    <!-- nobooks.tpl -->
    <p>There are no books to display.</p>

#### 28.3.2.2. 通过Zend_View_Interface接口使用模板系统

Some may find it easier to simply provide a Zend_View-compatible template engine. `Zend_View_Interface` defines the minimum interface needed for compatability: 实现一个与Zend_View兼容的模板系统是很简单的。你只需要实现`Zend_View_Interface`接口即可，该接口定义了要实现兼容的最低要求。

    /**
     * Return the actual template engine object
     * 返回实际模板系统的对象
     */
    public function getEngine();

    /**
     * Set the path to view scripts/templates
     * 设置视图脚本/模板的路径
     */
    public function setScriptPath($path);

    /**
     * Overloading methods for assigning template variables as object properties
     * 重载方法，用于将赋值给模板变量，以对象属性的形式
     */
    public function __set($key, $value);
    public function __get($key);
    public function __isset($key);
    public function __unset($key);

    /**
     * Manual assignment of template variables, or ability to assign multiple
     * variables en masse.
     * 手动设置模板变量，或者一次赋值多个变量的功能
     */
    public function assign($spec, $value = null);

    /**
     * Unset all assigned template variables
     */
    public function clearVars();

    /**
     * Render the template named $name
     */
    public function render($name);

Using this interface, it becomes relatively easy to wrap a third-party template engine as a Zend_View-compatible class. As an example, the following is one potential wrapper for Smarty: 使用这个接口，把第三方的模板系统封装成Zend_View兼容的类是相当容易的。例如，下面是封装Smarty的示例代码：

    require_once 'Zend/View/Interface.php';
    require_once 'Smarty.class.php';

    class Zend_View_Smarty implements Zend_View_Interface
    {
        /**
         * Smarty object
         * @var Smarty
         */
        protected $_smarty;

        /**
         * Constructor
         *
         * @param string $tmplPath
         * @param array $extraParams
         * @return void
         */
        public function __construct($tmplPath = null, $extraParams = array())
        {
            $this->_smarty = new Smarty;

            if (null !== $tmplPath) {
                $this->setScriptPath($tmplPath);
            }

            foreach ($extraParams as $key => $value) {
                $this->_smarty->$key = $value;
            }
        }

        /**
         * Return the template engine object
         *
         * @return Smarty
         */
        public function getEngine()
        {
            return $this->_smarty;
        }

        /**
         * Set the path to the templates
         *
         * @param string $path The directory to set as the path.
         * @return void
         */
        public function setScriptPath($path)
        {
            if (is_readable($path)) {
                $this->_smarty->template_dir = $path;
                return;
            }

            throw new Exception('Invalid path provided');
        }

        /**
         * Assign a variable to the template
         *
         * @param string $key The variable name.
         * @param mixed $val The variable value.
         * @return void
         */
        public function __set($key, $val)
        {
            $this->_smarty->assign($key, $val);
        }

        /**
         * Retrieve an assigned variable
         *
         * @param string $key The variable name.
         * @return mixed The variable value.
         */
        public function __get($key)
        {
            return $this->_smarty->get_template_vars($key);
        }

        /**
         * Allows testing with empty() and isset() to work
         *
         * @param string $key
         * @return boolean
         */
        public function __isset($key)
        {
            $value = $this->_smarty->get_template_vars($key);
            return null === $value;
        }

        /**
         * Allows unset() on object properties to work
         *
         * @param string $key
         * @return void
         */
        public function __unset($key)
        {
            $this->_smarty->clear_assign($key);
        }

        /**
         * Assign variables to the template
         *
         * Allows setting a specific key to the specified value, OR passing an array
         * of key => value pairs to set en masse.
         *
         * @see __set()
         * @param string|array $spec The assignment strategy to use (key or array of key
         * => value pairs)
         * @param mixed $value (Optional) If assigning a named variable, use this
         * as the value.
         * @return void
         */
        public function assign($spec, $value = null)
        {
            if (is_array($spec)) {
                $this->_smarty->assign($spec);
                return;
            }

            $this->_smarty->assign($spec, $value);
        }

        /**
         * Clear all assigned variables
         *
         * Clears all variables assigned to Zend_View either via {@link assign()} or
         * property overloading ({@link __get()}/{@link __set()}).
         *
         * @return void
         */
        public function clearVars()
        {
            $this->_smarty->clear_all_assign();
        }

        /**
         * Processes a template and returns the output.
         *
         * @param string $name The template to process.
         * @return string The output.
         */
        public function render($name)
        {
            return $this->_smarty->fetch($name);
        }
    }

在这个示例中，实例化`Zend_View_Smarty`而不是`Zend_View`，然后就像使用 `Zend_View`一样地使用它。

    $view = new Zend_View_Smarty();
    $view->setScriptPath('/path/to/templates');
    $view->book = 'Zend PHP 5 Certification Study Guide';
    $view->author = 'Davey Shafik and Ben Ramsey'
    $rendered = $view->render('bookinfo.tpl');

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