修改和重写json文件中的密钥

Question

public class JsonMain {
    public static void main(String[] args) throws IOException {
        String first = "chatMessage.json";
        String jsonSource = new String((Files.readAllBytes(Paths.get(first))),"UTF-8");
        //print the json file
        System.out.println(jsonSource);

        JSONObject obj = new JSONObject(jsonSource);
        JSONArray arr = new JSONArray(obj.getJSONArray("messages"));

        //iterate trough all the timestamp_ms and get the value
        for(int i=0; i< arr.length(); i++)
        {
            long time = (long)arr.getJSONObject(i).get("timestamp_ms");
            SimpleDateFormat sdf = new SimpleDateFormat();
            sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
            System.out.println(sdf.format(new Date(time)));
            //arr.put("timestamp_ms",sdf.format(new Date(time)));
        }

    }
}

这是json文件chatmessage.json

{
  "participants": [
    {
      "name": "User1"
    },
    {
      "name": "User2"
    }
  ],
  "messages": [
    {
      "sender_name": "User1",
      "timestamp_ms": 1620663455808,
      "content": "Hello ç á à â ã ",
      "type": "Generic",
      "is_unsent": false
    },
    {
      "sender_name": "User2",
      "timestamp_ms": 1620663401347,
      "content": "Hi, how are you?",
      "type": "Generic",
      "is_unsent": false
    },
    {
      "sender_name": "User1",
      "timestamp_ms": 1620662999730,
      "content": "\u00c3\u0089 to utf?",
      "type": "Generic",
      "is_unsent": false
    }
  ],
  "title": "chatTitle",
  "is_still_participant": true,
  "thread_type": "RegularGroup",
  "thread_path": "inbox/chatTitle_4hyfdfnnhw"
}

Answer 1

你很接近了。

只需要引用JSON消息对象而不是数组，然后重写文件。

您可以执行以下操作：

String first = "chatMessage.json";
String jsonSource = new String((Files.readAllBytes(Paths.get(first))),"UTF-8");
//print the json file
System.out.println(jsonSource);

JSONObject obj = new JSONObject(jsonSource);
JSONArray arr = new JSONArray(obj.getJSONArray("messages"));

//iterate trough all the timestamp_ms and get the value
for(int i=0; i< arr.length(); i++) {
    JSONObject currMessage = arr.getJSONObject(i);
    long time = (long) currMessage.get("timestamp_ms");
    SimpleDateFormat sdf = new SimpleDateFormat();
    sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
    System.out.println(sdf.format(new Date(time)));
    currMessage.put("timestamp_ms", sdf.format(new Date(time)));
}

Files.write(Paths.get(first), obj.toString().getBytes());

String output = new String((Files.readAllBytes(Paths.get(first))),"UTF-8");
System.out.println(output);

{
    "is_still_participant": true,
    "thread_type": "RegularGroup",
    "messages": [{
        "is_unsent": false,
        "sender_name": "User1",
        "timestamp_ms": "10.5.2021, 16:17",
        "type": "Generic",
        "content": "Hello ç á à â ã "
    }, {
        "is_unsent": false,
        "sender_name": "User2",
        "timestamp_ms": "10.5.2021, 16:16",
        "type": "Generic",
        "content": "Hi, how are you?"
    }, {
        "is_unsent": false,
        "sender_name": "User1",
        "timestamp_ms": "10.5.2021, 16:09",
        "type": "Generic",
        "content": "Ã\u0089 to utf?"
    }],
    "title": "chatTitle",
    "thread_path": "inbox/chatTitle_4hyfdfnnhw",
    "participants": [{
        "name": "User1"
    }, {
        "name": "User2"
    }]
}