用JAVA遞歸解析json文件

Question

我有一個包含章節和子章節的 json 文件......它的章節和子章節的數量並不總是相同：例如

{
"IDCours" : "CS10.44",
"title": " .... ",
"chapters": [
    {
        "idChapter": "1",
        "title": "Introduction",
        "chapters": [
            {
                "idChapter": "1.1",
                "title": "basics",
                "content" : " blab bla blab "
            },
            {
                "idChapter": "1.2",
                "title": "basics",
                "content" : " blab bla blab "
            }                
         ]
      },
      {
      "idChapter": "2",
        "title": "..... ",
        "chapters": [
            {
                "idChapter": "2.1",
                "title": " .... ",
                "content" : " blab bla blab "
            },
            {
                "idChapter": "2.2",
                "title": ".....",
                "content" : " blab bla blab ",
                "chapters": [
                      {
                        "idChapter": "2.2.1",
                        "title": " .... ",
                        "content" : " blab bla blab "
                      }
                    ]   
            }              
         ]
        }
]
}

所以，我認為應該遞歸完成，因為我事先不知道文件中有多少章節和子章節，子子章節

Answer 1

你不需要遞歸地做。 我通常使用 jackson 庫來處理 Json 的庫，所以這里是如何完成的。

public class mainClass {
  String IDCours;
  String title; 
  List<Chapters> chapters;
    public static class Chapters {
      double idChapter;
      String title;
      List<InnerChapters> chapters;

        @JsonIgnoreProperties(ignoreUnknown = true)
        public static class InnerChapters {
          double idChapter;
          String title;
          String content;
          List<InnerChapters> chapters;
   }
 }
}

並使用方法來解析您的 json，例如：

public static final ObjectMapper objMapper;
static {
        objMapper= new ObjectMapper();
        objMapper.registerModule(new JavaTimeModule());
    }

public static <T> List<T> fromJsonToList(String json, Class<T> clazz) throws IOException {
        CollectionType customClassCollection = MAPPER.getTypeFactory().constructCollectionType(List.class, clazz);
        return objMapper.readValue(json, customClassCollection);
    }

如果沒有章節列表並繼續解析您的 json，@JsonIgnoreProperties 注釋將忽略並且不會拋出異常。 嘗試一下。