java - 有没有使用 JSONObject 以 URL 格式传递 Json 数据的方法？

Question

我创建了一个 java URL 类，其中包含我的 Json 数据，并具有一些函数来获取我的 json 数据以进行一些数据比较，我发现 JSONObject 可能不支持将数据传递到 JSONObject。在我的例子中，我是否需要使用 JSONArray，因为我的 JSON 数据也具有数组结构？

     try
           {
            JSONObject obj = new JSONObject (); 
            obj.readJsonFromUrl(theUrl);
            System.out.println(obj.toString());
           }

       catch(MalformedURLException e)
       {
           System.out.print("your problem here ...1");
       }
   }
   else
   {
       System.out.print("Can't Connect");
   }

我确信这是给我错误消息的地方，因为它在我的编译器中返回此错误

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    The method readJsonFromUrl(URL) is undefined for the type JSONObject

还有一些关于 JSONObject readJsonFromUrl 方法的警告消息

private static JSONObject readJsonFromUrl(URL theUrl) throws IOException, JSONException {

任何人都可以向我解释 JSON 数据在 java 中如何工作？我看到很多 JSON 的 Java 类，这让我很困惑，比如 JSONObject、JSONArray、JSONValue。我在网上搜索了一些信息，但我也不是很清楚，因为我对 JSON 数据处理非常陌生

这是我的示例 json 数据，我需要的数据只是 scan_result

{  
   "data_id":"a71a3c2588c6472bb4daea41a0b58835",
   "file_info":{  
      "display_name":"",
      "file_size":242,
      "file_type":"Not available",
      "file_type_description":"Not available",
      "md5":"aa69ba384f22d0dc0551ace2fbb9ad55",
      "sha1":"09ceb54e65df3d3086b222e8643acffe451a6e8a",
      "sha256":"dcb46d6ae2a187f789c12f19c44bbe4b9a43bd200a3b306d5e9c1fcf811dc430",
      "upload_timestamp":"2016-11-18T09:09:08.390Z"
   },
   "process_info":{  
      "blocked_reason":"",
      "file_type_skipped_scan":false,
      "post_processing":{  
         "actions_failed":"",
         "actions_ran":"",
         "converted_destination":"",
         "converted_to":"",
         "copy_move_destination":""
      },
      "profile":"File scan",
      "progress_percentage":100,
      "result":"Allowed",
      "user_agent":""
   },
   "scan_results":{  
      "data_id":"a71a3c2588c6472bb4daea41a0b58835",
      "progress_percentage":100,
      "scan_all_result_a":"No Threat Detected",
      "scan_all_result_i":0,
      "scan_details":{  
         "Ahnlab":{  
            "def_time":"2016-11-08T15:00:00.000Z",
            "location":"local",
            "scan_result_i":0,
            "scan_time":1,
            "threat_found":""
         },
         "Avira":{  
            "def_time":"2016-11-08T00:00:00.000Z",
            "location":"local",
            "scan_result_i":0,
            "scan_time":133,
            "threat_found":""
         },
         "ClamAV":{  
            "def_time":"2016-11-08T10:28:00.000Z",
            "location":"local",
            "scan_result_i":0,
            "scan_time":94,
            "threat_found":""
         },
         "ESET":{  
            "def_time":"2016-11-08T00:00:00.000Z",
            "location":"local",
            "scan_result_i":0,
            "scan_time":38,
            "threat_found":""
         }
      },
      "start_time":"2016-11-18T09:09:08.405Z",
      "total_avs":4,
      "total_time":250
   },
   "vulnerability_info":{  

   }
} 

Answer 1

如上所述here ，有很多方法可以解决这个问题。要么你必须自己实现读取、解析操作(@Roland Illig 的回答)

//you have to implement the readJSON method 
InputStream is = new URL(url).openStream();
try {
  BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
  String jsonText = readAll(rd);
  JSONObject json = new JSONObject(jsonText);
  return json;
} finally {
  is.close();
}

或者你可以使用一个库。最知名和最广泛使用的库是 jackson和 gson 。总体来说，您尝试将 json 对象“映射”到一个类。

您有 json 文件:

{
“id”:1，
“姓名”:“埃里尼”，
"爱好":["音乐","哲学","足球"]
}

以及一个表示该文件并将存储值的类(根据您使用的库，可能有不同的要求，例如 getter、setter 等。)

public class Person {
   public int id;
   public String name;
   public List<String> hobbies = new ArrayList<String>();

   public String toString() {
       return name +" has the id: " + id + " the following hobbies" + hobbies.get(0) + " " + hobbies.get(2); 
   }
}

最后在你的主要方法中:

  public static void main(String[] args) throws IOException, ParseException {
    ObjectMapper mapper = new ObjectMapper();
    InputStream input = this.getClass().getResourceAsStream(FILE); //read your file. There are many ways to achieve this.
    ObjectMapper mapper = new ObjectMapper(); // just need one
    Person eirini = mapper.readValue(input, Person.class);
    System.out.println(eirini.toString());