CCSprite---CCTexture2D---CCTextureCache

---------------------createWithTexture-------------------------
bool CCSprite::initWithFile(const char *pszFilename)
{
    CCAssert(pszFilename != NULL,"Invalid filename for sprite");

    CCTexture2D *pTexture = CCTextureCache::sharedTextureCache()->addImage(pszFilename);
    if (pTexture)
    {
        CCRect rect = CCRectZero;
        rect.size = pTexture->getContentSize();
        return initWithTexture(pTexture,rect);
    }

    // don't release here.
    // when load texture Failed,it's better to get a "transparent" sprite than a crashed program
    // this->release(); 
    return false;
}
---------------------纹理缓存-------------------------
CCTexture2D * CCTextureCache::addImage(const char * path)
{
    CCAssert(path != NULL,"TextureCache: fileimage MUST not be NULL");

    CCTexture2D * texture = NULL;
    CCImage* pImage = NULL;
    // Split up directory and filename
    // MUTEX:
    // Needed since addImageAsync calls this method from a different thread
    
    //pthread_mutex_lock(m_pDictLock);

    std::string pathKey = path;

    pathKey = CCFileUtils::sharedFileUtils()->fullPathForFilename(pathKey.c_str());
    if (pathKey.size() == 0)
    {
        return NULL;
}

//纹理字典：判断纹理是否被加载
    texture = (CCTexture2D*)m_pTextures->objectForKey(pathKey.c_str());

    std::string fullpath = pathKey; // (CCFileUtils::sharedFileUtils()->fullPathFromRelativePath(path));
    if (! texture) 
    {
        std::string lowerCase(pathKey);
        for (unsigned int i = 0; i < lowerCase.length(); ++i)
        {
            lowerCase[i] = tolower(lowerCase[i]);
        }
        // all images are handled by UIImage except PVR extension that is handled by our own handler
        do 
        {
            if (std::string::npos != lowerCase.find(".pvr"))
            {
                texture = this->addPVRImage(fullpath.c_str());
            }
            else if (std::string::npos != lowerCase.find(".pkm"))
            {
                // ETC1 file format,only supportted on Android
                texture = this->addETCImage(fullpath.c_str());
            }
            else
            {
                CCImage::EImageFormat eImageFormat = CCImage::kFmtUnKnown;
                if (std::string::npos != lowerCase.find(".png"))
                {
                    eImageFormat = CCImage::kFmtPng;
                }
                else if (std::string::npos != lowerCase.find(".jpg") || std::string::npos != lowerCase.find(".jpeg"))
                {
                    eImageFormat = CCImage::kFmtJpg;
                }
                else if (std::string::npos != lowerCase.find(".tif") || std::string::npos != lowerCase.find(".tiff"))
                {
                    eImageFormat = CCImage::kFmtTiff;
                }
                else if (std::string::npos != lowerCase.find(".webp"))
                {
                    eImageFormat = CCImage::kFmtWebp;
                }
                
                pImage = new CCImage();
                CC_BREAK_IF(NULL == pImage);

                bool bRet = pImage->initWithImageFile(fullpath.c_str(),eImageFormat);
                CC_BREAK_IF(!bRet);

                texture = new CCTexture2D();
                
                if( texture &&
                    texture->initWithImage(pImage) )
                {
#if CC_ENABLE_CACHE_TEXTURE_DATA
                    // cache the texture file name
                    VolatileTexture::addImageTexture(texture,fullpath.c_str(),eImageFormat);
#endif
                    m_pTextures->setObject(texture,pathKey.c_str());
                    texture->release();
                }
                else
                {
                    CCLOG("cocos2d: Couldn't create texture for file:%s in CCTextureCache",path);
                }
            }
        } while (0);
    }

    CC_SAFE_RELEASE(pImage);

    //pthread_mutex_unlock(m_pDictLock);
    return texture;
}

-----------------------纹理缓存的体现------------------------
低效率：
	for (int i=0; i<1000; i++)
	{
		CCSprite* sprite_flower = CCSprite::create("hua.png");
		sprite_flower->setPosition(ccp(CCRANDOM_0_1()*480,CCRANDOM_0_1()*320));
		this->addChild(sprite_flower,1);
	}

高效率:
	CCSpriteBatchNode* spriteBatch = CCSpriteBatchNode::create("hua.png");
	this->addChild(spriteBatch,1);
	spriteBatch->setPosition(CCPointZero);
	for (int i=0; i<5000; i++)
	{
		CCSprite* sprite = CCSprite::createWithTexture(spriteBatch->getTexture());
		sprite->setPosition(ccp(CCRANDOM_0_1()*480,CCRANDOM_0_1()*320));
		spriteBatch->addChild(sprite);
	}