从服务器解析嵌套的 JSON

Question

I am working on an android project that parses JSON from a file on a server and converting the data into java objects to display the data using text views.

The JSON file that I am parsing is based on a collection of books. Within each book entry is an author which has nested child elements for the last and first name of that author. Some entries can have multiple authors.

JSON file:

{
  "bib": {
    "book": [
      {
        "year": "1994",
        "title": "TCP/IP Illustrated",
        "author": {
          "last": "Stevens",
          "first": "W."
        },
        "publisher": "Addison-Wesley",
        "price": "65.95"
      },
      {
        "year": "1992",
        "title": "Advanced Programming in the Unix environment",
        "author": {
          "last": "Stevens",
          "first": "W."
        },
        "publisher": "Addison-Wesley",
        "price": "65.95"
      },
      {
        "year": "2000",
        "title": "Data on the Web",
        "author": [
          {
            "last": "Abiteboul",
            "first": "Serge"
          },
          {
            "last": "Buneman",
            "first": "Peter"
          },
          {
            "last": "Suciu",
            "first": "Dan"
          }
        ],
        "publisher": "Morgan Kaufmann Puslishers",
        "price": "39.95"
      },
      {
        "year": "2012",
        "title": "Professional Android 4 application development",
        "author": {
          "last": "Meier",
          "first": "Reto"
        },
        "publisher": "ndianapolis : John Wiley and Sons",
        "price": "33.47"
      },
      {
        "year": "2017",
        "title": "Java Programming for Beginners: Learn the fundamentals of programming with Java",
        "author": {
          "last": "Lassoff",
          "first": "Mark"
        },
        "publisher": "Packt Publishing",
        "price": "23.99"
      },
      {
        "year": "2005",
        "title": "Head First Java",
        "author": [
          {
            "last": "Sierra",
            "first": "Kathy"
          },
          {
            "last": "Bates",
            "first": "Bert"
          },
        ],
        "publisher": "MO'Reilly Media; 2 edition",
        "price": "21.25"
      },
      {
        "year": "2013",
        "title": "XML for Dummies",
        "author": {
            "last": "Tittel",
            "first": "Ed"
        },
        "publisher": "Wiley; 4th edition",
        "price": "14.99"
      },
      {
        "year": "2019",
        "title": "Java XML and JSON: Document Processing for Java SE",
        "author": {
          "last": "Friesen",
          "first": "Jeff"
        },
        "publisher": "Apress; 2nd ed. edition",
        "price": "65.95"
      },
      {
        "year": "2016",
        "title": "Java Programming for Android Developers For Dummies (For Dummies (Computers))",
        "author": {
          "last": "Burd",
          "first": "Barry A."
        },
        "publisher": "John Wiley and Sons; 2nd edition",
        "price": "16.99"
      }
    ]
  }
}

JSON Parser:

  private class parseJSON extends AsyncTask<Void, Void, List<Book>> {

        private final String TAG = parseJSON.class.getSimpleName();
        @Override
        protected List<Book> doInBackground(Void... voids) {
            Log.i(TAG, "Start Async to get books.");
            ArrayList<Book> bookArray = new ArrayList<>(0);

            String jsonUrl = getApplication().getString(R.string.json_feed);
            HttpHandler httpHandler = new HttpHandler();
            String jsonString = httpHandler.makeJsonServiceCall(jsonUrl);

            Log.i(TAG, "Response from url: " + jsonString);

            if( jsonString != null) {
                try {
                    JSONObject root = new JSONObject(jsonString);

                    // Get JSON array node.
                    JSONArray books = root.getJSONObject("bib").getJSONArray("book");
                    // Looping through all the books.
                    for (int i = 0; i < books.length(); i++) {
                        JSONObject jsonBook = books.getJSONObject(i);


                        String year = jsonBook.getString("year");
                        String title = jsonBook.getString("title");


                        String author = jsonBook.getString("author");

                        String publisher = jsonBook.getString("publisher");
                        String price = "£" + jsonBook.getString("price");

                        final Book bookObject = new Book(year, title, author, publisher, price);

                        //Add the new books to our result array.
                        bookArray.add(bookObject);

                    }

                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
            return bookArray;
        }

        @Override
        protected void onPostExecute( List<Book> books) {
            super.onPostExecute(books);
            Log.e(TAG, "Populate UI recycler view with json converted data.");
            bookList.setValue(books);
        }
    }

What is the best way I can accomplish this?

Answer 1

Use Gson by google, in your gradle add:

implementation 'com.google.code.gson:gson:2.8.6'

and you get it like:

Book bookObject = new Gson().fromJson("json", Book.class);