我正在努力将SignalK JSON对象拆分为代表每个值的规范JSON项。
原始JSON如下所示:
{
"mmsi": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"name": "Mona",
"navigation": {
"position": {
"timestamp": "1991-09-03T03:5:36.000Z",
"latitude": 51.763691,
"longitude": 9.501367,
"altitude": 0.000000,
"source": "N0183-01"
},
"courseOverGroundTrue": {
"value": 23.000000
},
"speedOverGround": {
"value": 2.010289
}
},
"environment": {
"depth": {
"belowTransducer": {
"value": 12.700000
}
},
"wind": {
"angleApparent": {
"value": 0.174533
},
"speedApparent": {
"value": 0.000000
}
}}}
需要转换的JSON看起来像这样,JSON元素代表每个值,项目命名代表值的整个路径。
{
"items": [{
"columns": {
"assetId": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"description": "EnvironmentWindSpeedApparent",
"isStep": false,
"name": "EnvironmentWindSpeedApparent",
"timestamps": 1523962903470,
"type": "numerical",
"values": 0.0
},
"key": "20180417-130143470EnvironmentWindSpeedApparent5377770-4ee4-4a4b-3230-888037332031"
}, {
"columns": {
"assetId": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"description": "EnvironmentWindAngleApparent",
"isStep": false,
"name": "EnvironmentWindAngleApparent",
"timestamps": 1523962903470,
"type": "numerical",
"values": 0.174533
},
"key": "20180417-130143470EnvironmentWindAngleApparent5377770-4ee4-4a4b-3230-888037332031"
}, {
"columns": {
"assetId": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"description": "EnvironmentDepthBelowTransducer",
"isStep": false,
"name": "EnvironmentDepthBelowTransducer",
"timestamps": 1523962903470,
"type": "numerical",
"values": 12.7
},
"key": "20180417-130143470EnvironmentDepthBelowTransducer5377770-4ee4-4a4b-3230-888037332031"
}, {
"columns": {
"assetId": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"description": "NavigationPositionLongitude",
"isStep": false,
"name": "NavigationPositionLongitude",
"timestamps": 1523962903470,
"type": "numerical",
"values": 9.501367
},
"key": "20180417-130143470NavigationPositionLongitude5377770-4ee4-4a4b-3230-888037332031"
}, {
"columns": {
"assetId": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"description": "NavigationPositionLatitude",
"isStep": false,
"name": "NavigationPositionLatitude",
"timestamps": 1523962903470,
"type": "numerical",
"values": 51.763691
},
"key": "20180417-130143470NavigationPositionLatitude5377770-4ee4-4a4b-3230-888037332031"
}, {
"columns": {
"assetId": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"description": "NavigationCourseOverGroundTrue",
"isStep": false,
"name": "NavigationCourseOverGroundTrue",
"timestamps": 1523962903470,
"type": "numerical",
"values": 23.0
},
"key": "20180417-130143470NavigationCourseOverGroundTrue5377770-4ee4-4a4b-3230-888037332031"
}, {
"columns": {
"assetId": "urn:mrn:signalk:uuid:5377770-4ee4-4a4b-3230-888037332031",
"description": "NavigationSpeedOverGround",
"isStep": false,
"name": "NavigationSpeedOverGround",
"timestamps": 1523962903470,
"type": "numerical",
"values": 2.010289
},
"key": "20180417-130143470NavigationSpeedOverGround5377770-4ee4-4a4b-3230-888037332031"
}
]}
如何以灵活的方式进行此转换,以便更改原始JSON中可用的子节点? 我现在正以简单的方式对其进行转换,但想知道是否可以使用JsonReader,gson或其他迭代原始JSON对象的方式来完成它。
答案 0 :(得分:0)
我最终定义了表示转换后的json的对象结构,并编写了一个自定义序列化器来进行转换。这可能是更有效的方法,但这种方法似乎工作正常。
public class SignalKDeserializer implements JsonDeserializer<TargetObject> {
//written based on examples from http://www.javacreed.com/gson-deserialiser-example/
final TargetObject targetObject = new TargetObject ();
@Override
public TargetObject deserialize(final JsonElement json, final Type typeOfT, final JsonDeserializationContext context)
throws JsonParseException {
final JsonObject jsonObject = json.getAsJsonObject();
traverse (jsonObject,0,"", mmsi);
return targetObject;
}
private void traverse (JsonObject jsonObject, Integer level, String parentName, String mmsi) {
Set<String> keys = jsonObject.keySet();
Iterator<?> keysIterator = keys.iterator ();
while( keysIterator.hasNext ()) {
String key = (String) keysIterator.next ();
String signalName = parentName+upperCaseFirst (key); //setting signalName to complete path of value
if (jsonObject.get (key) instanceof JsonObject) {
traverse ((jsonObject.get (key)).getAsJsonObject (),level+1,upperCaseFirst (signalName),mmsi);
} else if (jsonObject.get (key) instanceof JsonElement) {
if (level>0) {
try {
final Double value = jsonObject.get(key).getAsDouble ();
calendar = Calendar.getInstance ();
Long timeStamp = calendar.getTimeInMillis ();
Item targetItem = new Item ();
targetItem.columns.setIsStep (false);
targetItem.columns.setAssetId (mmsi);
targetItem.columns.setTimestamps (calendar.getTimeInMillis ());
targetItem.columns.setType ("numerical");
targetItem.columns.setDescription (signalName);
targetItem.columns.setValues (value);
targetItem.columns.setName (signalName);
targetItem.setKey (signaldateformat.format (timeStamp) + mmsi);
targetObject.items.add (targetItem);
}
catch (NumberFormatException n) {
// Expected, the value is non numerical and will not be transformed
}
}
}
}
}}
我正在使用我的主类中的序列化程序,如下所示:
final GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(TargetObject.class, new SignalKDeserializer ());
final Gson gson = gsonBuilder.create();
TargetObject targetObject = gson.fromJson (jsonSignalK,TargetObject.class);
String jsonOutString = gson.toJson (targetObject);
jsonOutString包含我需要的转换后的json。