The ObjectMapper ৷ ক্লাস জ্যাকসন লাইব্রেরির সবচেয়ে গুরুত্বপূর্ণ ক্লাস। আমরা readValue() ব্যবহার করে একটি JSON কে জাভা অবজেক্টে রূপান্তর করতে পারি ObjectMapper এর পদ্ধতি ক্লাস, এই পদ্ধতিটি প্রদত্ত JSON সামগ্রী স্ট্রিং থেকে একটি JSON সামগ্রীকে ডিসিরিয়ালাইজ করে।
সিনট্যাক্স
public <T> readValue(String content, JavaType valueType) throws IOException, JsonParseException, JsonMappingException
উদাহরণ
import java.io.*;
import java.util.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
public class JSONToJavaObjectTest {
public static void main(String args[]) throws JsonGenerationException, JsonMappingException, IOException {
Employee emp1 = new Employee();
emp1.setFirstName("Raja");
emp1.setLastName("Ramesh");
emp1.setId(115);
emp1.getTechnologies().add("Java");
emp1.getTechnologies().add("Selenium");
emp1.getTechnologies().add("Spark");
ObjectMapper mapper = new ObjectMapper();
String jsonStr = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(emp1);
System.out.println(jsonStr);
System.out.println("Deserializing JSON to Object:");
Employee emp2 = mapper.readValue(jsonStr, Employee.class);
System.out.println(emp2.getId() + " " + emp2.getFirstName() + " " + emp2.getLastName() + " " + emp2.getTechnologies());
}
}
// Employee class
class Employee {
private int id;
private String firstName;
private String lastName;
private List technologies = new ArrayList<>();
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public List getTechnologies() {
return technologies;
}
public void setTechnologies(List technologies) {
this.technologies = technologies;
}
} আউটপুট
{
"id" : 115,
"firstName" : "Raja",
"lastName" : "Ramesh",
"technologies" : [ "Java", "Selenium", "Spark" ]
}
Deserializing JSON to Object:
115 Raja Ramesh [Java, Selenium, Spark] 