code: function( str , dest ){
          var _spilt  = "cb==cb",
              _imgs   = str.replace( /\s+/gi , " " ).replace( /url\(([^\)]*)\)/gi , _spilt + "$1" + _spilt ).split( _spilt ),
              _md5,
              _img,
              _dest;
          for( var i = _imgs.length; i--; ){
              if( i % 2 ){
                  _img    = tool.getResourcePath( _imgs[ i ] , dest );
                  if( !grunt.file.exists( _img ) ){
                      continue;
                  };
                  if( !config.resources[ _img ] ){
                      _md5    = tool.getFileMD5( _img );
                      config.resources[ _img ] = _md5;
                  } else {
                      _md5 = config.resources[ _img ];
                  };
                  _imgs[ i ] = "url('../" + _md5 + "')";
              };
          };
          return _imgs.join( "" );
      }
docs: /*!
  修正对应内容的图片/其它资源的引用
  @str    {string}    内容
  @dest   {string}    目标文件地址
  return  修正后的内容