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面向对象升华：面向对象的认识----新生的初识、面向对象的番外----思想的梦游篇（1）、面向对象的认识---如何找出类
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吐槽：有人反馈了这样的一个信息，说该文章越到最后越难看懂，跟不上节奏，也有的人说小帅帅的能力怎么飙的那么快，是不是我比较蠢。也有的直接看文字，不看代码，代码太难懂了。
其实我这几天也一直在思考这个问题，所以没办法就去开展了一些面向对象的课程，希望对那些跟不上的有些帮助。其实说真的，读者不反馈的话，我只好按照我认为的小帅帅去开展课程了。
第二十天
起点：手把手教你做关键词匹配项目（搜索引擎）---- 第一天
回顾：手把手教你做关键词匹配项目（搜索引擎）---- 第十九天
话说小帅帅为了解决那个分词算法写出了初版，他拿给于老大看的时候，被要求重写了。
原因有以下几点：
1. 如何测试，测试数据呢？
2. Splitter是不是做了太多事情?
3. 连衣裙xxl裙连衣裙这种 有重复词组怎么办？
小帅帅拿着这些问题，开始重构。
首先他发现了这点，中文、英文和中英文的判断，以及长度的计算，他把这个写成了类：
<?<span>php
</span><span>class</span><span> UTF8 {
</span><span>/*</span><span>*
* 检测是否utf8
* @param $char
* @return bool
</span><span>*/</span>
<span>public</span> <span>static</span> <span>function</span> is(<span>$char</span><span>){
</span><span>return</span> (<span>preg_match</span>("/^([".<span>chr</span>(228)."-".<span>chr</span>(233)."]{1}[".<span>chr</span>(128)."-".<span>chr</span>(191)."]{1}[".<span>chr</span>(128)."-".<span>chr</span>(191)."]{1}){1}/",<span>$char</span>) ||
<span>preg_match</span>("/([".<span>chr</span>(228)."-".<span>chr</span>(233)."]{1}[".<span>chr</span>(128)."-".<span>chr</span>(191)."]{1}[".<span>chr</span>(128)."-".<span>chr</span>(191)."]{1}){1}$/",<span>$char</span>) ||
<span>preg_match</span>("/([".<span>chr</span>(228)."-".<span>chr</span>(233)."]{1}[".<span>chr</span>(128)."-".<span>chr</span>(191)."]{1}[".<span>chr</span>(128)."-".<span>chr</span>(191)."]{1}){2,}/",<span>$char</span><span>));
}
</span><span>/*</span><span>*
* 计算utf8字的个数
* @param $char
* @return float|int
</span><span>*/</span>
<span>public</span> <span>static</span> <span>function</span> length(<span>$char</span><span>) {
</span><span>if</span>(self::is(<span>$char</span><span>))
</span><span>return</span> <span>ceil</span>(<span>strlen</span>(<span>$char</span>)/3<span>);
</span><span>return</span> <span>strlen</span>(<span>$char</span><span>);
}
</span><span>/*</span><span>*
* 检测是否为词组
* @param $word
* @return bool
</span><span>*/</span>
<span>public</span> <span>static</span> <span>function</span> isPhrase(<span>$word</span><span>){
</span><span>if</span>(self::length(<span>$word</span>)<=1<span>)
</span><span>return</span> <span>false</span><span>;
</span><span>return</span> <span>true</span><span>;
}
}</span>小帅帅又考虑到词典的来源有可能来自多个地方，比如我给的测试数据，这样不就是可以解决于老大说到无法测试的问题了，小帅帅把词典的来源抽成了个类，类如下：
<?<span>php
</span><span>class</span><span> DBSegmentation {
</span><span>public</span> <span>$cid</span><span>;
</span><span>/*</span><span>*
* 获取类目下分词的词组数据
* @return array
</span><span>*/</span>
<span>public</span> <span>function</span><span> transferDictionary(){
</span><span>$ret</span> = <span>array</span><span>();
</span><span>$sql</span> = "select word from category_linklist where cid='<span>$this</span>->cid'"<span>;
</span><span>$words</span> = DB::makeArray(<span>$sql</span><span>);
</span><span>foreach</span>(<span>$words</span> <span>as</span> <span>$strWords</span><span>){
</span><span>$words</span> = <span>explode</span>(",",<span>$strWords</span><span>);
</span><span>foreach</span>(<span>$words</span> <span>as</span> <span>$word</span><span>){
</span><span>if</span>(UTF8::isPhrase(<span>$word</span><span>)){
</span><span>$ret</span>[] = <span>$word</span><span>;
}
}
}
</span><span>return</span> <span>$ret</span><span>;
}
}
</span><span>class</span><span> TestSegmentation {
</span><span>public</span> <span>function</span><span> transferDictionary(){
</span><span>$words</span> = <span>array</span><span>(
</span>"连衣裙,连衣",
"XXL,xxl,加大,加大码",
"X码,中码",
"外套,衣,衣服,外衣,上衣",
"女款,女士,女生,女性"<span>
);
</span><span>$ret</span> = <span>array</span><span>();
</span><span>foreach</span>(<span>$words</span> <span>as</span> <span>$strWords</span><span>){
</span><span>$words</span> = <span>explode</span>(",",<span>$strWords</span><span>);
</span><span>foreach</span>(<span>$words</span> <span>as</span> <span>$word</span><span>){
</span><span>if</span>(UTF8::isPhrase(<span>$word</span><span>)){
</span><span>$ret</span>[] = <span>$word</span><span>;
}
}
}
</span><span>return</span> <span>$ret</span><span>;
}
}</span>那么Splitter 就专心分词把，代码如下：
<span>class</span><span> Splitter {
</span><span>public</span> <span>$keyword</span><span>;
</span><span>private</span> <span>$dictionary</span> = <span>array</span><span>();
</span><span>public</span> <span>function</span> setDictionary(<span>$dictionary</span> = <span>array</span><span>()){
</span><span>usort</span>(<span>$dictionary</span>,<span>function</span>(<span>$a</span>,<span>$b</span><span>){
</span><span>return</span> (UTF8::length(<span>$a</span>)>UTF8::length(<span>$b</span>))?1:-1<span>;
});
</span><span>$this</span>->dictionary = <span>$dictionary</span><span>;
}
</span><span>public</span> <span>function</span><span> getDictionary(){
</span><span>return</span> <span>$this</span>-><span>dictionary;
}
</span><span>/*</span><span>*
* 把关键词拆分成词组或者单词
* @return KeywordEntity $keywordEntity
</span><span>*/</span>
<span>public</span> <span>function</span> <span>split</span><span>(){
</span><span>$remainKeyword</span> = <span>$this</span>-><span>keyword;
</span><span>$keywordEntity</span> = <span>new</span> KeywordEntity(<span>$this</span>-><span>keyword);
</span><span>foreach</span>(<span>$this</span>->dictionary <span>as</span> <span>$phrase</span><span>){
</span><span>$matchTimes</span> = <span>preg_match_all</span>("/<span>$phrase</span>/",<span>$remainKeyword</span>,<span>$matches</span><span>);
</span><span>if</span>(<span>$matchTimes</span>>0<span>){
</span><span>$keywordEntity</span>->addElement(<span>$phrase</span>,<span>$matchTimes</span><span>);
</span><span>$remainKeyword</span> = <span>str_replace</span>(<span>$phrase</span>,"::",<span>$remainKeyword</span><span>);
}
}
</span><span>$remainKeywords</span> = <span>explode</span>("::",<span>$remainKeyword</span><span>);
</span><span>foreach</span>(<span>$remainKeywords</span> <span>as</span> <span>$splitWord</span><span>){
</span><span>if</span>(!<span>empty</span>(<span>$splitWord</span><span>)){
</span><span>$keywordEntity</span>->addElement(<span>$splitWord</span><span>);
}
}
</span><span>return</span> <span>$keywordEntity</span><span>;
}
}
</span><span>class</span><span> KeywordEntity {
</span><span>public</span> <span>$keyword</span><span>;
</span><span>public</span> <span>$elements</span> = <span>array</span><span>();
</span><span>public</span> <span>function</span> __construct(<span>$keyword</span><span>){
</span><span>$this</span>->keyword = <span>$keyword</span><span>;
}
</span><span>public</span> <span>function</span> addElement(<span>$word</span>,<span>$times</span>=1<span>){
</span><span>if</span>(<span>isset</span>(<span>$this</span>->elements[<span>$word</span><span>])){
</span><span>$this</span>->elements[<span>$word</span>]->times += <span>$times</span><span>;
}</span><span>else</span>
<span>$this</span>->elements[] = <span>new</span> KeywordElement(<span>$word</span>,<span>$times</span><span>);
}
</span><span>/*</span><span>*
* @desc 计算UTF8字符串权重
* @param string $word
* @return float
</span><span>*/</span>
<span>public</span> <span>function</span> calculateWeight(<span>$word</span><span>)
{
</span><span>$element</span> = <span>$this</span>->elements[<span>$word</span><span>];
</span><span>return</span> <span>ROUND</span>(<span>strlen</span>(<span>$element</span>->word)*<span>$element</span>->times / <span>strlen</span>(<span>$this</span>->keyword), 3<span>);
}
}
</span><span>class</span><span> KeywordElement {
</span><span>public</span> <span>$word</span><span>;
</span><span>public</span> <span>$times</span><span>;
</span><span>public</span> <span>function</span> __construct(<span>$word</span>,<span>$times</span><span>){
</span><span>$this</span>->word = <span>$word</span><span>;
</span><span>$this</span>->times = <span>$times</span><span>;
}
}</span>他把算权重的也丢给了一个类专门去处理。
小帅帅写完之后，也顺手写了测试实例：
<?<span>php </span><span>$segmentation</span> = <span>new</span><span> TestSegmentation(); </span><span>$splitter</span> = <span>new</span><span> Splitter(); </span><span>$splitter</span>->setDictionary(<span>$segmentation</span>-><span>transferDictionary()); </span><span>$splitter</span>->keyword = "连衣裙xxl裙连衣裙"<span>; </span><span>$keywordEntity</span> = <span>$splitter</span>-><span>split</span><span>(); </span><span>var_dump</span>(<span>$keywordEntity</span>);
这样就算你的算法怎么改，它也能从容面对了。
小帅帅理解了这个，当你觉得类做的事情太多的时候，可以考虑下单一职责原则。
单一职责原则：一个类，只有一个引起它变化的原因。应该只有一个职责。每一个职责都是变化的一个轴线，如果一个类有一个以上的职责，这些职责就耦合在了一起。这会导致脆弱的设计。当一个职责发生变化时，可能会影响其它的职责。另外，多个职责耦合在一起，会影响复用性。例如：要实现逻辑和界面的分离。【来自百度百科】
当于老大提到是不是有其他分词算法的时候，我们能不能拿来用，小帅帅很高兴，因为现在它的代码是多么美好。
小帅帅如何玩转第三方分词扩展，请继续关注下回分解：手把手教你做关键词匹配项目（搜索引擎）---- 第二十一天
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