使用Jackson解析json文件中的多个对象

Question

我的json文件包含多个对象：

[
{
      "name":"Move",
      "$$hashKey":"object:79",
      "time":11.32818,
      "endTime":18.615535
   },
   {
      "name":"First Red Flash",
      "$$hashKey":"object:77",
      "time":15.749153
   },
   {
      "name":"Pills",
      "subEventTypes":[
         "pull down bottle",
         "unscrew lid",
         "dump pills out",
         "screw lid on",
         "put bottle away"
      ],
      "$$hashKey":"object:82",
      "time":25.130175,
      "subEventSplits":[
         26.092057,
         27.425881,
         31.841594,
         34.268093
      ],
      "endTime":36.234827
   }

 }

有没有办法用杰克逊解析这个Json文件？ 或者是否有其他可用的库允许我以这种格式解析Json文件？ 到目前为止，这是我的代码：

    File file = new File("data.json");
    JsonFactory jsonFactory = new JsonFactory();
    JsonParser parser = jsonFactory.createJsonParser(file);
    while(parser.nextToken()!=JsonToken.END_OBJECT)
    {
            //how to read each token

    }

Answer 1

杰克逊应该解析你提到的JSON文件。 创建一个类，如下所示

Class Holder {
    String name;
    List<String> subEventTypes = new ArrayList<>();
    String $$hashKey;
    Double time;
    List<Double> subEventSplits = new ArrayList<>()
    DOuble endTime;
}

Class MapperClass{
    List<Holder> list = new ArrayList<>();
}

解析它如下所示

ObjectMapper mapper = new ObjectMapper();

//JSON from file to Object
MapperClass values = mapper.readValue(new File("c:\\values.json"), MapperClass.class);

有关详细信息，请参阅此链接

Answer 2

您可以使用树模型，就像

ObjectMapper m = new ObjectMapper();
JsonNode rootNode = m.readTree(new File("data.json"));
Iterator<JsonNode> it = rootNode.getElements();

while(it.hasNext()) {
    System.out.println("element : " + it.next().toString());
}

然后你会看到你想要的:)