从 REST API 过滤 JSON 对象的疑惑

Question

I am trying to filter some objects from a JSON response in Java. Below is my code. I need to get the Genre Object from the response and print it separately. Anyone who knows how that can be done?

I have did the RestAPI call from omdb. This is a just a simple project which I am trying to build. To basically analyze the type of genres that were released in particular years.

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import sun.org.mozilla.javascript.internal.json.JsonParser;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;

public class OmdbApiService {

    //public static final String Search_Url = "http://www.omdbapi.com/?s=TITLE&apikey=APIKEY";
    //public static final String Search_Url = "http://www.omdbapi.com/?t=TITLE&plot=PLOT&apikey=APIKEY";
    public static final String Search_Plot = "http://www.omdbapi.com/?i=TITLE&plot=PLOT&apikey=APIKEY";

    private static String sendGetRequest(String requestURL){
        StringBuffer response = new StringBuffer();

        try {
            URL url = new URL(requestURL);
            HttpURLConnection connection =
                    (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setRequestProperty("Accept", "*/*");
            connection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
            InputStream stream = connection.getInputStream();
            InputStreamReader reader = new InputStreamReader(stream);
            BufferedReader buffer = new BufferedReader(reader);
            String line;
            while ((line = buffer.readLine()) != null) {
                response.append(line);
            }
            buffer.close();
            connection.disconnect();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return response.toString();
    }

    private static String searchMoviebyID(String title, String plot, String key) {
        try {
            title = URLEncoder.encode(title, "UTF-8"); // To omit the spaces in between the titles
            plot = URLEncoder.encode(plot, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        String requestUrl = Search_Plot
                .replaceAll("TITLE", title)
                .replaceAll("PLOT", plot)
                .replaceAll("APIKEY", key);
        return sendGetRequest(requestUrl);
    }

    /*private static String filterbyGenres(){
        try {



        }

    }*/


    public static void main(String[] args) {
        String jsonResponse = OmdbApiService.searchMoviebyID("tt1345836","full","6d****87");
        System.out.println(jsonResponse);

        /*Gson gson = new GsonBuilder().setPrettyPrinting().create();
        JsonElement jsonElement =  new JsonParser().parse(jsonResponse);
        System.out.println(gson.toJson(jsonResponse));*/

    }
}

Output:

{"Title":"The Dark Knight Rises","Year":"2012","Rated":"PG-13","Released":"20 Jul 2012","Runtime":"164 min","Genre":"Action, Thriller","Director":"Christopher Nolan","Writer":"Jonathan Nolan (screenplay), Christopher Nolan (screenplay), Christopher Nolan (story), David S. Goyer (story), Bob Kane (characters)","Actors":"Christian Bale, Gary Oldman, Tom Hardy, Joseph Gordon-Levitt","Plot":"Despite his tarnished reputation after the events of The Dark Knight, in which he took the rap for Dent's crimes, Batman feels compelled to intervene to assist the city and its police force which is struggling to cope with Bane's plans to destroy the city.","Language":"English, Arabic","Country":"UK, USA","Awards":"Nominated for 1 BAFTA Film Award. Another 38 wins & 102 nominations.","Poster":"https://m.media-amazon.com/images/M/MV5BMTk4ODQzNDY3Ml5BMl5BanBnXkFtZTcwODA0NTM4Nw@@._V1_SX300.jpg","Ratings":[{"Source":"Internet Movie Database","Value":"8.4/10"},{"Source":"Rotten Tomatoes","Value":"87%"},{"Source":"Metacritic","Value":"78/100"}],"Metascore":"78","imdbRating":"8.4","imdbVotes":"1,372,667","imdbID":"tt1345836","Type":"movie","DVD":"03 Dec 2012","BoxOffice":"$448,130,642","Production":"Warner Bros. Pictures","Website":"http://www.thedarkknightrises.com/","Response":"True"}

This is the output, can I know how do I filter out just the Genre in this output.

Extra help : If someone could tell me how to print the output in separate lines, it will be helpful.

Answer 1

You can parse it using the jackson library. Can you try this code?

Jackson:

// jackson library import
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

// ...
private static String filterByGenres(String jsonResponse) {
    String genres = "";
    try {
        ObjectMapper mapper = new ObjectMapper();
        JsonNode jsonNode = mapper.readValue(jsonResponse, JsonNode.class);

        // Considering when there are no API results
        if(jsonNode != null || jsonNode.get("Genre") != null) {
            genres = jsonNode.get("Genre").asText();
        }
    } catch (Exception e) {
        // handle to exception
    }
    return genres;
}

public static void main(String[] args) {
    String jsonResponse = OmdbApiService.searchMoviebyID("tt1345836", "full", "6d****87");

    // The result of the API is the argument.(json format string)
    String genres = filterByGenres(jsonResponse);
    System.out.println(genres); // Action, Thriller
}

Gson:

public static void main(String[] args) {
    String jsonResponse = OmdbApiService.searchMoviebyID("tt1345836", "full", "6d****87");

    JsonParser jsonParser = new JsonParser();
    JsonObject jsonObject = jsonParser.parse(jsonResponse).getAsJsonObject();
    JsonElement genreObject = jsonObject.get("Genre");
    System.out.println(genreObject.getAsString()); // Action, Thriller
}

Extra help:

Extra help : If someone could tell me how to print the output in separate lines, it will be helpful.

public void prettyPrint() {
    String jsonResponse = OmdbApiService.searchMoviebyID("tt1345836", "full", "6d****87");

    Gson gson = new GsonBuilder().setPrettyPrinting().create();
    JsonElement jsonElement = new JsonParser().parse(jsonResponse);
    String prettyJson = gson.toJson(jsonElement);
    System.out.println(prettyJson);
}