How to implement a json parser here?

Question

I created a post request with json and it works pretty well. But now I want to insert the output of this json post request into my database.

So I need to create a json parser to seperate the string like this: "Bestellnummer:1", "Besteller:8195529", "Zeit: 2019-09-27 15:50:07", "Artikelnummer:76194", "Anzahl:1", "Preis:2.968"... (next Artikelnummer and so on...).

Bestellnummer = orderid, Besteller = customerid, Zeit = time, Artikelnummer=articleid, Anzahl = number of article, Preis= price

I tried to do something like a parser in my code, but I never did something like this befor and unfortuntly don't know how to involve this parser in my code.

I hope u can help me

One example for my json Output:

{"Bestellnummer":"1","Besteller":"8195529","Zeit":"2019-09-27 15:50:07","Artikel":[{"Artikelnummer":"76194","Anzahl":"1","Preis":"2.968"},{"Artikelnummer":"61681","Anzahl":"1","Preis":"7.147"},{"Artikelnummer":"111756","Anzahl":"1","Preis":"9.29"},{"Artikelnummer":"14227","Anzahl":"1","Preis":"0"}]}

Code:

private static String dirPath = "https://hauteuchdrum.informatik.uni-siegen.de/propra/aufgaben/ws1920/index.php";
         public ArrayList<String> Bestellung(){
            File file = new File (dirPath + "//array_complex.json");
            ArrayList <String> test = new ArrayList<String>();
            try {
                String str = "{ \"Bestellnummer\": [1,2,3,4,5] }";

                // holt alle 47550 bestellungen vom json  
                for (int i=1; i<2;i++) {
                String POST_PARAMS = "json={\"bid\":\"bid\", \"getorder\":\""+i+"\"}";
                    //System.out.println(POST_PARAMS);

                JSONObject obj1 = new JSONObject(POST_PARAMS);
                JSONArray arr=obj1.getJSONArray("Bestellnummer");
                for (int z=0; z<arr.length();z++) {
                    String post_id = arr.getJSONObject(z).getString("Bestellnummer");
                    System.out.println(post_id);
                }
                 URL obj = new URL("https://hauteuchdrum.informatik.uni-siegen.de/propra/aufgaben/ws1920/index.php");
                 HttpURLConnection postConnection = (HttpURLConnection) obj.openConnection();
                 postConnection.setRequestMethod("POST");
                 postConnection.setRequestProperty("connection", "Keep-Alive");
                 postConnection.setDoOutput(true);
                 java.io.OutputStream os = postConnection.getOutputStream();
                    os.write(POST_PARAMS.getBytes());
                    os.flush();
                    os.close();

                    int responseCode = postConnection.getResponseCode();
                    //System.out.println("POST Response Code :  " + responseCode);
                   // System.out.println("POST Response Message : " + postConnection.getResponseMessage());
                    if (responseCode == HttpURLConnection.HTTP_OK) { //success
                        BufferedReader in = new BufferedReader(new InputStreamReader(postConnection.getInputStream()));
                        String inputLine;
                        StringBuffer response = new StringBuffer();
                        while ((inputLine = in.readLine()) != null) {
                            response.append(inputLine);
                        } 
                        in.close();
                        // print result
                      //  System.out.println(response.toString());
                        test.add(response.toString());
                     //   java.util.Iterator<String> it = test.iterator();
                     // while (it.hasNext()) {
                       //   System.out.println(it.next());
                    //    }

                    }
        }
            }
            catch (Exception e) {
                System.out.println();
            }
            return test;
        }

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– Makyen ♦, Commented Nov 11, 2019 at 16:40

LHCHIN · Accepted Answer · 2019-11-04 01:36:02Z

If what you want to do is to insert the HTTP response string into database, I strongly recommend you to deserialize the string to POJOs as follows:

Declare 2 classes - MyResponse and Artikel. Artikel is for storing the content of JOSN object in JSON array, and I use List<Artikel> for the JSON array. BTW, I also use @JsonProperty(provided in Jackson) to map JSON keys with uppercase to variables with lowercase.

class MyResponse {
    @JsonProperty(value="Bestellnummer")
    private String bestellnummer;
    @JsonProperty(value="Besteller")
    private String besteller;
    @JsonProperty(value="Zeit")
    private String zeit;
    @JsonProperty(value="Artikel")
    private List<Artikel> artikel;

    //general getters and setters
}

class Artikel {
    @JsonProperty(value="Artikelnummer")
    private String artikelnummer;
    @JsonProperty(value="Anzahl")
    private String anzahl;
    @JsonProperty(value="Preis")
    private String preis;

    //general getters and setters
}

Now, you can use Jackson (one of the most popular JSON libraries) to deserialize the HTTP response to our POJOs. And you can manipulate these POJOs for DB operation easily.

ObjectMapper mapper = new ObjectMapper();
MyResponse myResponse = mapper.readValue(response.toString(), MyResponse.class);
myResponse.getArtikel().forEach(System.out::println);

Console output

Artikel [artikelnummer=76194, anzahl=1, preis=2.968]
Artikel [artikelnummer=61681, anzahl=1, preis=7.147]
Artikel [artikelnummer=111756, anzahl=1, preis=9.29]
Artikel [artikelnummer=14227, anzahl=1, preis=0]

Florian Hergenhahn · Accepted Answer · 2019-11-03 18:59:03Z

Because you provided too less information to come up with a more detailed answer I came up with the following code.

JSONObject main = new JSONObject(data);
String orderNumber = main.getString("Bestellnummer"); // Retrieving the order number
String orderUserId = main.getString("Besteller"); // Retrieving the orderUserId
String time = main.getString("Zeit"); // Retrieving the current time

JSONArray articles = main.getJSONArray("Artikel"); // Getting articles as JSON Array
for (int i = 0; i < articles.length(); i++) { // Looping tough the articles
    JSONObject article = articles.getJSONObject(i); // Getting the article JSON Object
    String articleNumber = article.getString("Artikelnummer"); // Retrieving the Article number
    String amount = article.getString("Anzahl"); // Retrieving the amount
    String price = article.getString("Pris"); // Retrieving the price

    // Your code...
}

I hope this helps you.

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