Как распарсить json в java?

506

14 января 2017, 11:48

Как распарсить такой код?

{
    "prim1":
    {
        "age": 100,
        "name": "mky100.com",
        "messages": [
            "msg 100",
            "msg 200",
            "msg 300"
        ]
    },
    "prim2":
    {
        "age": 90,
        "name": "mky90.com",
        "messages": [
            "msg 90",
            "msg 200",
            "msg 300"
        ]
    },
    "prim3":
    {
        "age": 80,
        "name": "mky80.com",
        "messages": [
            "msg 80",
            "msg 200",
            "msg 300"
        ]
    }
}

Пытаюсь так, но выводит ошибки:

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
public class aa {
  public static void main(String[] args) {
    JSONParser parser = new JSONParser();
    try {
      Object obj = parser.parse(new FileReader("/Users/Katerina/Desktop/Java обучение/aa.json "));
      JSONObject jsonObject = (JSONObject) obj;
      JSONArray prim = jsonObject.getAsJsonArray("prim1");
      for (JSONArray user : prim) {
        JSONObject userObject = user.getAsJsonArray();
        userObject.get("name"); 
        String name = (String) jsonObject.get("name");
        System.out.println(name);
        long age = (Long) jsonObject.get("age");
        System.out.println(age);
        // loop array
        JSONArray msg = (JSONArray) jsonObject.get("messages");
        Iterator<String> iterator = msg.iterator();
        while (iterator.hasNext()) {
          System.out.println(iterator.next());
        }
      }
    } catch (FileNotFoundException e) {
      e.printStackTrace();
      System.out.println("1111");
    } catch (IOException e) {
      e.printStackTrace();
      System.out.println("2222");
    } catch (ParseException e) {
      e.printStackTrace();
      System.out.println("3333");
    }
  }
}

Ошибки:

/Users/Katerina/Desktop/Java обучение/aa.java:20: error: cannot find symbol
        JSONArray prim = jsonObject.getAsJsonArray("prim1");
                                   ^
  symbol:   method getAsJsonArray(String)
  location: variable jsonObject of type JSONObject
/Users/Katerina/Desktop/Java обучение/aa.java:21: error: incompatible types
        for (JSONArray user : prim) {
                              ^
  required: JSONArray
  found:    Object
/Users/Katerina/Desktop/Java обучение/aa.java:22: error: cannot find symbol
            JSONObject userObject = user.getAsJsonArray();
                                        ^
  symbol:   method getAsJsonArray()
  location: variable user of type JSONArray
/Users/Katerina/Desktop/Java обучение/aa.java:33: warning: [unchecked] unchecked conversion
        Iterator<String> iterator = msg.iterator();
                                                ^
  required: Iterator<String>
  found:    Iterator
3 errors
1 warning

Answer 1

Очевидно, это ошибка компиляции. Видимо не та библиотека или версия.

С библиотекой json-simple:

<dependency>
    <groupId>com.googlecode.json-simple</groupId>
    <artifactId>json-simple</artifactId>
    <version>1.1.1</version>
</dependency>

Это делается следующим образом:

String filename = "file.json";
try (BufferedReader reader = Files.newBufferedReader(filename)) {
        JSONParser parser = new JSONParser();
        JSONObject jsonObject = (JSONObject) parser.parse(reader);
        ((Map<String, JSONObject>) jsonObject)
                .entrySet()
                .forEach(entry -> {
                    String key = entry.getKey();
                    JSONObject people = entry.getValue();
                    System.out.println(key);
                    System.out.println(people.get("age"));
                    System.out.println(people.get("name"));
                    JSONArray messages = (JSONArray) people.get("messages");
                    messages.forEach(System.out::println);
                });
    }