C语言和设计模式（享元模式） 【文章都是来自网络，只要自己吸取了就是自己的】

享元模式看上去有点玄乎，但是其实也没有那么复杂。我们还是用示例说话。比如说，大家在使用电脑的使用应该少不了使用WORD软件。使用WORD呢， 那就少不了设置模板。什么模板呢，比如说标题的模板，正文的模板等等。这些模板呢，又包括很多的内容。哪些方面呢，比如说字体、标号、字距、行距、大小等等。

[cpp]
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typedef struct _Font
{
int type;
int sequence;
int gap;
int lineDistance;

void (*operate)(struct _Font* pFont);

}Font;

[cpp]
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typedef struct _FontFactory

{
Font** ppFont;
int number;
int size;

Font* GetFont(struct _FontFactory* pFontFactory, int type, int sequence, int gap, int lineDistance);

}FontFactory;

typedef struct _FontFactory
{
Font** ppFont;
int number;
int size;

Font* GetFont(struct _FontFactory* pFontFactory, int type, int sequence, int gap, int lineDistance);
}FontFactory;

这里的GetFont即使对当前的Font进行判断，如果Font存在，那么返回；否则创建一个新的Font模式。

[cpp]
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Font* GetFont(struct _FontFactory* pFontFactory, int type, int sequence, int gap, int lineDistance)

{
int index;

Font* pFont;
Font* ppFont;

if(NULL == pFontFactory)

return NULL;

for(index = 0; index < pFontFactory->number; index++)

{
if(type != pFontFactory->ppFont[index]->type)

continue;

if(sequence != pFontFactory->ppFont[index]->sequence)

continue;

if(gap != pFontFactory->ppFont[index]->gap)

continue;

if(lineDistance != pFontFactory->ppFont[index]->lineDistance)

continue;

return pFontFactory->ppFont[index];

}

pFont = (Font*)malloc(sizeof(Font));

assert(NULL != pFont);
pFont->type = type;
pFont->sequence = sequence;
pFont->gap = gap;
pFont->lineDistance = lineDistance;

if(pFontFactory-> number < pFontFactory->size)

{
pFontFactory->ppFont[index] = pFont;
pFontFactory->number ++;
return pFont;

}

ppFont = (Font**)malloc(sizeof(Font*) * pFontFactory->size * 2);

assert(NULL != ppFont);
memmove(ppFont, pFontFacoty->ppFont, pFontFactory->size);

free(pFontFactory->ppFont);
pFontFactory->size *= 2;
pFontFactory->number ++;
ppFontFactory->ppFont = ppFont;
return pFont;

}