首页 \ 问答 \ 有没有办法使用SAX解析器使用访问者模式？(Is there a way to use the Visitor pattern using a SAX Parser?)

有没有办法使用SAX解析器使用访问者模式？(Is there a way to use the Visitor pattern using a SAX Parser?)

 我对此很好奇：如果我需要使用Sax解析器来提高效率（这是一个很大的文件）。 通常我使用这样的东西：  
public class Example extends DefaultHandler
{
    private Stack stack = new Stack ();

    public void startElement (String uri, String local, String qName, Attributes atts) throws SAXException
    {
        stack.push (qName);
    }

    public void endElement (String uri, String local, String qName) throws SAXException
    {
        if ("line".equals (qName))
            System.out.println ();

        stack.pop ();
    }

    public void characters (char buf [], int offset, int length) throws SAXException
    {
        if (!"line".equals (stack.peek ()))
            return;

        System.out.write (new String (buf, offset, length));
    }
}
 
 从这里采取的例子。  
 Sax已经是一个访问者模式的实现，但在我的情况下，我只需要获取每个元素的内容，并根据元素本身的性质对其进行处理。  
 我典型的XML文件是这样的：  
<?xml version="1.0" encoding="utf-8"?>
<labs xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <auth>
        <uid> </uid>
        <gid> </gid>
        <key> </key>
    </auth>
    <campaign>
        <sms>
            <newsletter>206</newsletter>
            <message>
                <from>Da Definire</from>
                <subject>Da definire</subject>
                <body><![CDATA[Testo Da Definire]]></body>
            </message>
            <delivery method="manual"></delivery>
            <recipients>
                <db>276</db>
                <filter>
                    <test>1538</test>
                </filter>
                <new_recipients>
                    <csv_file>Corso2012_SMS.csv</csv_file>
                </new_recipients>
            </recipients>
        </sms>
    </campaign>
</labs>
 
 当我在csv_file节点中时，我需要获取文件名并从该文件上传用户，如果我在filter/test ，则需要检查过滤器是否存在等等。 有没有办法使用SAX来应用访问者模式？ 

I'm curious about this: if I need to use a Sax parser to boost up efficiency (it's a big file). Usually I use something like this: 
public class Example extends DefaultHandler
{
    private Stack stack = new Stack ();

    public void startElement (String uri, String local, String qName, Attributes atts) throws SAXException
    {
        stack.push (qName);
    }

    public void endElement (String uri, String local, String qName) throws SAXException
    {
        if ("line".equals (qName))
            System.out.println ();

        stack.pop ();
    }

    public void characters (char buf [], int offset, int length) throws SAXException
    {
        if (!"line".equals (stack.peek ()))
            return;

        System.out.write (new String (buf, offset, length));
    }
}
 
example taken from here. 
The Sax is already an implementation of a Visitor Pattern but in my case I just need to take the content of every element and do something with it according to the nature of the element itself. 
My typical XML file is something like: 
<?xml version="1.0" encoding="utf-8"?>
<labs xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <auth>
        <uid> </uid>
        <gid> </gid>
        <key> </key>
    </auth>
    <campaign>
        <sms>
            <newsletter>206</newsletter>
            <message>
                <from>Da Definire</from>
                <subject>Da definire</subject>
                <body><![CDATA[Testo Da Definire]]></body>
            </message>
            <delivery method="manual"></delivery>
            <recipients>
                <db>276</db>
                <filter>
                    <test>1538</test>
                </filter>
                <new_recipients>
                    <csv_file>Corso2012_SMS.csv</csv_file>
                </new_recipients>
            </recipients>
        </sms>
    </campaign>
</labs>
 
When I'm in the csv_file node I need to take the filename and upload users from that file, if I'm in the filter/test I need to check if the filter exists and so on. Is there a way to apply the Visitor Pattern with SAX?

原文：https://stackoverflow.com/questions/10850989

更新时间：2023-11-25 21:11

最满意答案

 当您更新帖子时，您宁愿向给定资源发送POST （或更好的PATCH / PUT - http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html ）请求。  
 也就是说，您将在网址中包含已编辑的行键，并将您的方法更改为以下内容：  
// route
Route::post('/postedit/{id}', array('as' => 'postedit', 'uses' => 'AdminController@postEdit'))
    ->before('auth');

// controller
public function postEdit($id)
{
    // if no posts with $id found, throws exception - catch it and eg. show 404
    $post = Post::findOrFail($id);

    $rules = [
        'title' => 'required',
        'article' => 'required',
        'slug' => 'required|unique:posts,slug,'.$id, // to ignore this row in unique check
        'category' => 'required'
    ];

    // validate

    $post->fill($input)->save(); // fill() in order to use mass-assignement check

    // alternatively you can just update:
    // $post->update($input);
    // but then make sure $input has only elements corresponding to the table columns
 
 另外，请阅读有关路由分组的信息 ，因此您无需单独向这些路由添加before('auth') 。 

When you update a post, you'd rather send a POST (or better PATCH/PUT- http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html) request to given resource. 
That said, you would include edited row key in the url, and change your method to something like this: 
// route
Route::post('/postedit/{id}', array('as' => 'postedit', 'uses' => 'AdminController@postEdit'))
    ->before('auth');

// controller
public function postEdit($id)
{
    // if no posts with $id found, throws exception - catch it and eg. show 404
    $post = Post::findOrFail($id);

    $rules = [
        'title' => 'required',
        'article' => 'required',
        'slug' => 'required|unique:posts,slug,'.$id, // to ignore this row in unique check
        'category' => 'required'
    ];

    // validate

    $post->fill($input)->save(); // fill() in order to use mass-assignement check

    // alternatively you can just update:
    // $post->update($input);
    // but then make sure $input has only elements corresponding to the table columns
 
Additionally, read about route grouping, so you don't need to add before('auth') to those routes separately.

有没有办法使用SAX解析器使用访问者模式？(Is there a way to use the Visitor pattern using a SAX Parser?)

最满意答案

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