cocos2d-x3.2源码分析(一）类FileUtils--实现把资源放在Resource

当你创建TMXTiledMap* tilemap=TMXTiledMap::create("test1.tmx")或Sprite *sprite=Sprite("HelloWorld.p-ng"),有没有产生这样的疑问--为什么把资源test1.tmx和HelloWorld.png放在项目目录下的Resources文件中即可直接引用而不用标明具体路径，并且可以在多个平台下引用？或许很多人就会这样说：“别人告诉我放在这个文件夹中就可以了，我自己使用确实可行，也没有出错，我就没有多去探究了”。如果你想知道这具体原因，就要阅读下面的分析了。如果你并不关心其原因，你可以关闭这个网页了。

我以TMXTiledMap::Create函数为讲解对象。

<spanstyle="font-size:18px;">boolTMXTiledMap::initWithTMXFile( CCASSERT(tmxFile.size()>0,"FastTMXTiledMap:tmxfileshouldnotbeempty");
1. setContentSize(Size::ZERO);
2. TMXMapInfo*mapInfo=TMXMapInfo::create(tmxFile);
3. if(!mapInfo)
4. returnfalse;
5. }
6. CCASSERT(!mapInfo->getTilesets().empty(),"FastTMXTiledMap:Mapnotfound.Pleasecheckthefilename.");
7. buildWithMapInfo(mapInfo);
8. true;
9. }</span>

<spanstyle="font-size:18px;">TMXMapInfo*TMXMapInfo::create( TMXMapInfo*ret=newTMXMapInfo();
1. }</span>

boolTMXMapInfo::initWithTMXFile( internalInit(tmxFile,"");
1. returnparseXMLFile(_TMXFileName.c_str());
2. </span>

<spanstyle="font-size:18px;">voidTMXMapInfo::internalInit(conststd::string&tmxFileName,conststd::string&resourcePath)
1. if(tmxFileName.size()>0)
2. _TMXFileName=FileUtils::getInstance()->fullPathForFilename(tmxFileName);
3. if(resourcePath.size()>0)
4. _resources=resourcePath;
5. ...
6. }</span>

<spanstyle="font-size:18px;">std::stringFileUtils::fullPathForFilename(conststd::string&filename)
1. std::stringfullpath;
2. for(autosearchIt=_searchPathArray.cbegin();searchIt!=_searchPathArray.cend();++searchIt)
3. for(autoresolutionIt=_searchResolutionsOrderArray.cbegin();resolutionIt!=_searchResolutionsOrderArray.cend();++resolutionIt)
4. fullpath=this->getPathForFilename(newFilename,*resolutionIt,*searchIt);
6. if(fullpath.length()>0)
7. //Usingthefilenamepassedinaskey.
8. _fullPathCache.insert(std::make_pair(filename,fullpath));
9. returnfullpath;
10. }</span>

<spanstyle="font-size:18px;">std::stringFileUtils::getPathForFilename(conststd::string&filename,153); background-color:inherit; font-weight:bold">conststd::string&resolutionDirectory,153); background-color:inherit; font-weight:bold">conststd::string&searchPath)
1. std::stringfile=filename;
2. std::stringfile_path="";
3. size_tpos=filename.find_last_of("/");
4. if(pos!=std::string::npos)
5. file_path=filename.substr(0,pos+1);
6. file=filename.substr(pos+1);
7. //searchPath+file_path+resourceDirectory
8. std::stringpath=searchPath;
9. path+=file_path;
10. path+=resolutionDirectory;
11. path=getFullPathForDirectoryAndFilename(path,file);
12. //CCLOG("getPathForFilename,fullPath=%s",path.c_str());
13. returnpath;
14. }</span>

<spanstyle="font-size:18px;">std::stringFileUtils::getFullPathForDirectoryAndFilename(conststd::string&directory,0); background-color:inherit">//getdirectory+filename,safelyadding'/'asnecessary
1. std::stringret=directory;
2. if(directory.size()&&directory[directory.size()-1]!='/'){
3. ret+='/';
4. ret+=filename;
6. //ifthefiledoesn'texist,returnanemptystring
7. if(!isFileExistInternal(ret)){
8. ret="";
9. returnret;
10. }</span>

boolFileUtils::init()
1. _searchPathArray.push_back(_defaultResRootPath);
2. _searchResolutionsOrderArray.push_back("");
3. true;
4. }</span>

<spanstyle="font-size:18px;">#include"base/CCPlatformConfig.h"
1. #ifCC_TARGET_PLATFORM==CC_PLATFORM_WIN32
2. #include"CCStdC.h"
3. #include"platform/CCCommon.h"
4. #include"platform/CCApplicationProtocol.h"
5. #include<string></span>

<spanstyle="font-size:18px;">FileUtils*FileUtils::getInstance()
1. if(s_sharedFileUtils==nullptr)
2. s_sharedFileUtils=newFileUtilsWin32();
3. if(!s_sharedFileUtils->init())
4. deletes_sharedFileUtils;
5. s_sharedFileUtils=nullptr;
6. CCLOG("ERROR:CouldnotinitCCFileUtilsWin32");
7. returns_sharedFileUtils;
8. }</span>

boolFileUtilsWin32::init()
1. _checkPath();
2. _defaultResRootPath=s_resourcePath;
3. returnFileUtils::init();
4. }</span>

staticvoid_checkPath()
1. if(0==s_resourcePath.length())
2. WCHARutf16Path[CC_MAX_PATH]={0};
3. GetCurrentDirectoryW(sizeof(utf16Path)-1,utf16Path);
4. charutf8Path[CC_MAX_PATH]={0};
5. intnNum=WideCharToMultiByte(CP_UTF8,utf16Path,-1,utf8Path,153); background-color:inherit; font-weight:bold">sizeof(utf8Path),nullptr,nullptr);
6. s_resourcePath=convertPathFormatToUnixStyle(utf8Path);
7. s_resourcePath.append("/");
8. }</span>

boolFileUtilsAndroid::init()
1. _defaultResRootPath="assets/";
2. returnFileUtils::init();
3. }</span>

</span>

<spanstyle="font-size:18px;">std::stringFileUtilsWin32::getPathForFilename( std::stringunixFileName=convertPathFormatToUnixStyle(filename);
1. std::stringunixResolutionDirectory=convertPathFormatToUnixStyle(resolutionDirectory);
2. std::stringunixSearchPath=convertPathFormatToUnixStyle(searchPath);
3. returnFileUtils::getPathForFilename(unixFileName,unixResolutionDirectory,unixSearchPath);
4. }</span>

（编辑：李大同）

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