Java中json文档中叶节点的所有路径的输出列表

Z时代
2024-01-10
分类：问答

例如：给定此json文档：

{ "store": { "book": [ { "category": "reference", "author": "Nigel Rees", "title": "Sayings of the Century", "price": 8.95 }, { "category": "fiction", "author": "Herman Melville", "title": "Moby Dick", "isbn": "0-553-21311-3", "price": 8.99 }, ], "bicycle": { "color": "red", "price": 19.95 } }, "expensive": 10 }

我想产生（类似）此输出：

store.book.category: "reference" store.book.author: "Nigel Rees" store.book.title: "Sayings of the Century" store.book.price: 8.95 store.book.category: "fiction" store.book.author: "Herman Melville" store.book.title: "Moby Dick" store.book.isbn: "0-553-21311-3" store.book.price: 8.99 store.bicycle.color: "red" store.bicycle.price: 19.95 expensive:10

与其使用原始文本，不如使用基于健壮的json库（gson，jackson等）之一的高效解决方案。

回答：

事实证明，使用Gson做到这一点非常容易，尤其是使用2.3中引入的JsonReader.getPath（）方法时。

static void parseJson(String json) throws IOException {
    JsonReader reader = new JsonReader(new StringReader(json));
    reader.setLenient(true);
    while (true) {
        JsonToken token = reader.peek();
        switch (token) {
            case BEGIN_ARRAY:
                reader.beginArray();
                break;
            case END_ARRAY:
                reader.endArray();
                break;
            case BEGIN_OBJECT:
                reader.beginObject();
                break;
            case END_OBJECT:
                reader.endObject();
                break;
            case NAME:
                reader.nextName();
                break;
            case STRING:
                String s = reader.nextString();
                print(reader.getPath(), quote(s));
                break;
            case NUMBER:
                String n = reader.nextString();
                print(reader.getPath(), n);
                break;
            case BOOLEAN:
                boolean b = reader.nextBoolean();
                print(reader.getPath(), b);
                break;
            case NULL:
                reader.nextNull();
                break;
            case END_DOCUMENT:
                return;
        }
    }
}
static private void print(String path, Object value) {
    path = path.substring(2);
    path = PATTERN.matcher(path).replaceAll("");
    System.out.println(path + ": " + value);
}
static private String quote(String s) {
    return new StringBuilder()
            .append('"')
            .append(s)
            .append('"')
            .toString();
}
static final String REGEX = "\\[[0-9]+\\]";
static final Pattern PATTERN = Pattern.compile(REGEX);