java - Jackson 将动态 json 转换为 map

Question

我遇到一个问题，json 的某些结构是固定的，而某些部分是动态的。最终输出必须是类型为

的对象

Map<String,List<Map<String,String>>>

我正在粘贴 Jackson 工作的示例 json 代码 -

    {
  "contentlets": [
    {
      "template": "8f8fab8e-0955-49e1-a2ed-ff45e3296aa8",
      "modDate": "2017-01-06 13:13:20.0",
      "cachettl": "0",
      "title": "New Early Warnings",
      "subscribeToListIi": "am@zz.com",
      "inode": "15bd497-1d8e-4bc7-b0f4-c799ed89fdc9",
      "privacySetting": "public",
      "__DOTNAME__": "New gTLD Early Warnings",
      "activityStatus": "Completed",
      "host": "10b6f94a-7671-4e08-9f4b-27bca80702e7",
      "languageId": 1,
      "createNotification": false,
      "folder": "951ff45c-e844-40d4-904f-92b0d2cd0c3c",
      "sortOrder": 0,
      "modUser": "dotcms.org.2897"
    }
  ]
}


ObjectMapper mapper = new  ObjectMapper();
Map<String,List<Map<String,String>>> myMap=mapper.readValue(responseStr.getBytes(), new TypeReference<HashMap<String,List<Map<String,String>>>>() {});

上面的代码工作正常，但是当 json 更改为(基本上添加了元数据标记)时，它无法转换为 map 。

{
  "contentlets": [
    {
      "template": "8f8fab8e-0955-49e1-a2ed-ff45e3296aa8",
      "modDate": "2017-01-06 13:13:20.0",
      "cachettl": "0",
      "title": "New gTLD Early Warnings",
      "subscribeToListIi": "aml@bb.com",
      "inode": "15bd4057-1d8e-4bc7-b0f4-c799ed89fdc9",
      "metadata": {
        "author": "jack",
        "location": "LA"
      },
      "privacySetting": "public",
      "__DOTNAME__": "New gTLD Early Warnings",
      "activityStatus": "Completed",
      "host": "10b6f94a-7671-4e08-9f4b-27bca80702e7",
      "languageId": 1,
      "createNotification": false,
      "folder": "951ff45c-e844-40d4-904f-92b0d2cd0c3c",
      "sortOrder": 0,
      "modUser": "dotcms.org.2897"
    }
  ]
}    

Answer 1

这是预期的，因为元数据值的类型不是String。如果您相应地更改 map 的类型，那么它就可以工作:

Map<String,List<Map<String,Object>>> myMap = mapper.readValue(reader, new TypeReference<HashMap<String,List<Map<String,Object>>>>() {});

当然，您会遇到映射中的值不是同一类型的问题。所以你需要问自己你想要的数据结构是什么以及如何进一步处理它。但是，无法将 json 结构反序列化为简单的 String。