当不知道架构时，从Java中的localhost提取服务器解析DBpedia JSON

Question

This is probably a quick answer to a very novice question. I am having trouble wrapping my head around how to get JSON text dbpedia extraction server running from a localhost. The server is running fine, I followed the official instructions .

I have read the other StackOverflow questions about parsing JSON in java and what I am having trouble understanding is how to parse the JSON when the schema or structure is unknown.

For example in my code I try to grab the JSON from localhost and put it into a java object. But all the examples of parsing JSON online use a predesigned java object and all the JSON keys are mapped to an object's fields. (ie Employee class: name,job,email,id,phone)

String sURL = "http://localhost:9999/server/extraction/en/extract?title=" + wikipage + "&revid=&format=rdf-json&extractors=custom"; //just a string

URL url = new URL(sURL);
Reader pageReader = new InputStreamReader(url.openConnection().getInputStream());

Gson g = new Gson();
JsonReader jr = new JsonReader(new InputStreamReader((InputStream) request.getContent()));
jr.setLenient(true);

JsonParser jp = new JsonParser();
JsonElement root = jp.parse(new InputStreamReader((InputStream) request.getContent())); //convert the input stream to a json element
JsonObject rootobj = root.getAsJsonObject(); //may be an array, may be an object.

I now have this "json object" for the film "Blue Velvet" I can parse/iterate with jr.hasNext() or rootobj.getAsJsonArray(). Am I going about this correctly?

I feel like I am reinventing the wheel. Is there a standard way of parsing DBpedia JSON objects in Java?

Answer 1

At least the Jackson JSON library allows you to parse incoming JSON into a Map. If the keys and values of the JSON can be of any type, then you need to use Map<Object, Object> , which is a bit cumbersome, but anyways this should work:

ObjectMapper mapper = new ObjectMapper();
Map<Object, Object> parsedJSON =  mapper.readValue(incomingJSON,
                        mapper.getTypeFactory().constructMapType(
                          LinkedHashMap.class,
                          Object.class, 
                          Object.class));