In Java entity classes and JSON objects are converted to each other

When we need to use JSON object to encapsulate data, we tend to write a lot of code and copy and paste a lot. In order to use POJO's idea, we can convert JSON into entity objects for operation

package myUtil;
 
import java.io.IOException;
 
import myProject.Student;
import myProject.StudentList;
 
import org.codehaus.jackson.map.ObjectMapper;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

public class JSONUtil {
  
  public static<T> Object JSONToObj(String jsonStr,Class<T> obj) {
    T t = null;
    try {
      ObjectMapper objectMapper = new ObjectMapper();
      t = objectMapper.readValue(jsonStr,
          obj);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return t;
  }
  
  public static<T> JSONObject objectToJson(T obj) throws JSONException, IOException {
    ObjectMapper mapper = new ObjectMapper(); 
    // Convert object to JSON string 
    String jsonStr = "";
    try {
       jsonStr = mapper.writeValueAsString(obj);
    } catch (IOException e) {
      throw e;
    }
    return new JSONObject(jsonStr);
  }
  public static void main(String[] args) throws JSONException, IOException {
    JSONObject obj = null;
    obj = new JSONObject();
    obj.put("name", "213");
    obj.put("age", 27);
    JSONArray array = new JSONArray();
    array.put(obj);
    obj = new JSONObject();
    obj.put("name", "214");
    obj.put("age", 28);
    array.put(obj);
    Student stu = (Student) JSONToObj(obj.toString(), Student.class);
    JSONObject objList = new JSONObject();
    objList.put("student", array);
    System.out.println("objList:"+objList);
    StudentList stuList = (StudentList) JSONToObj(objList.toString(), StudentList.class);
    System.out.println("student:"+stu);
    System.out.println("stuList:"+stuList);
    System.out.println("#####################################");
    JSONObject getObj = objectToJson(stu);
    System.out.println(getObj);
  }
}

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