我有以下来自 API 的 Json 响应，如何在角度服务代码中获取数组的键
{“消息”：{“affenpinscher”：[]，“非洲”：[]，“airedale”：[]，“秋田”：[]，“appenzeller”：[]，“澳大利亚”：[“牧羊人”] ,"basenji":[],"beagle":[],"bluetick":[],"borzoi":[],"bouvier":[],"boxer":[],"brabancon":[], "briard":[],"buhund":["norwegian"],"bulldog":["boston","english","french"],"bullterrier":["staffordshire"],"cattledog":[ "澳大利亚"],"吉娃娃":[],"chow":[],"clumber":[],"cockapoo":[],"collie":["border"],"coonhound":[], “柯基犬”：[“羊毛衫”]，“cotondetulear”：[]，“腊肠犬”：[]，dalmatian":[],"dane":["great"],"deerhound":["scottish"],"dhole":[],"dingo":[],"doberman":[],"elkhound" :["norwegian"],"entlebucher":[],"eskimo":[],"finnish":["lapphund"],"frise":["bichon"],"germanshepherd":[],"greyhound ":["italian"],"groenendael":[],"havanese":[],"hound":["afghan","basset","blood","english","ibizan","plott" ,"walker"],"husky":[],"keeshond":[],"kelpie":[],"komondor":[],"kuvasz":[],"labradoodle":[],"拉布拉多":[],"莱昂伯格":[],"拉萨":[],"雪橇犬":[],"malinois":[],"maltese":[],"mastiff":["bull","english","tibetan"],"mexicanhairless":[],"mix":[],"mountain":[ “伯尔尼”，“瑞士”]，“纽芬兰”：[]，“奥特猎犬”：[]，“ovcharka”：[“白种人”]，“巴比龙”：[]，“北京人”：[]，“彭布罗克” :[],"pinscher":["miniature"],"pitbull":[],"pointer":["german","germanlonghair"],"pomeranian":[],"poodle":["miniature" ,"标准","玩具"],"哈巴狗":[],"puggle":[],"比利牛斯":[],"redbone":[],"猎犬":["切萨皮克","curly" “平涂”、“金色”]、“脊背”:["罗得西亚"],"罗威纳犬":[],"saluki":[],"萨摩耶犬":[],"schipperke":[],"雪纳瑞犬":["giant","miniature"]," setter":["english","gordon","irish"],"sheepdog":["english","shetland"],"shiba":[],"shihtzu":[],"spaniel":[ “布伦海姆”、“布列塔尼”、“可卡犬”、“爱尔兰”、“日本”、“苏塞克斯”、“威尔士”]、“斯普林格”：[“英语”]、“stbernard”：[]、“梗犬”： [“美国”，“澳大利亚”，“贝灵顿”，“边境”，“凯恩”，“丹迪”，“福克斯”，“爱尔兰”，“克里蓝”，“莱克兰”，“诺福克”，“诺维奇”，“patterdale”、“russell”、“苏格兰”、“sealyham”、“silky”、“tibetan”、“toy”、“westhighland”、“wheaten”、“yorkshire”]、“vizsla”：[]、“waterdog” ":["spanish"],"weimaraner":[],"whippet":[],"wolfhound":["irish"]},"status":"success"}