JavaでJSON-libAPIを使用してJSONオブジェクトをBeanに変換するにはどうすればよいですか？

import net.sf.json.JSONObject;
public class ConvertJSONObjToBeanTest {
   public static void main(String[] args) {
      mployee emp = new Employee("Sai", "Ram", 30, "Bangalore");
      JSONObject jsonObj = JSONObject.fromObject(emp);
      System.out.println(jsonObj.toString(3)); // pretty print JSON
      emp = (Employee)JSONObject.toBean(jsonObj, Employee.class);
      System.out.println(emp.toString());
   }
   // Employee class
   public static class Employee {
      private String firstName, lastName, address;
      private int age;
      public Employee() {
      }
      public Employee(String firstName, String lastName, int age, String address) {
         super();
         this.firstName = firstName;
         this.lastName = lastName;
         this.age = age;
         this.address = address;
      }
      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 int getAge() {
         return age;
      }
      public void setAge(int age) {
         this.age = age;
      }
      public String getAddress() {
         return address;
      }
      public void setAddress(String address) {
         this.address = address;
      }
      public String toString() {
         return "Employee[ " +
                "firstName = " + firstName +
                ", lastName = " + lastName +
                ", age = " + age +
                ", address = " + address +
                " ]";
      }
   }
}

出力

{
 "firstName": "Sai",
 "lastName": "Ram",
 "address": "Bangalore",
 "age": 30
}
Employee[ firstName = Sai, lastName = Ram, age = 30, address = Bangalore ]