6 ways to create objects in java

6 ways to create objects:

public class NewObject {
    public static void main(String[] args) throws InstantiationException, IllegalAccessException {
        NewObject newObject = new NewObject();
        //1.反射构造器
        Person person1 = newObject.construct();
        System.out.println(person1);
        //2.newInstance
        Person person2 = newObject.classNewInstance();
        System.out.println(person2);
        //3.clone
        Person person3 = newObject.byClone();
        System.out.println(person3);
        //4.序列化
        Person serial = newObject.serial();
        System.out.println(serial.getAge());
        //5.unsafe
        Person unsafe = newObject.unsafe();
        System.out.println(unsafe);
        //6.new
        Person p=new Person();

    }

    /**
     * 反射构造器构造
     *
     * @return
     */
    public Person construct() {
        Class aClass = null;
        try {
            aClass = Class.forName("cn.xys.atomic.unsafe.Person");
            Constructor constructor = aClass.getConstructor(null);
            Person person = (Person) constructor.newInstance(null);
            return person;
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * 2.newInstance
     *
     * @return
     * @throws IllegalAccessException
     * @throws InstantiationException
     */
    public Person classNewInstance() throws IllegalAccessException, InstantiationException {
        return Person.class.newInstance();
    }

    /**
     * 克隆
     *
     * @return
     */
    public Person byClone() {
        try {
        //需实现Cloneable接口，并重写clone()方法
            Person person = new Person();
            return (Person) person.clone();

        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 反序列化
     * @return
     */
    public Person serial() {

        Person person = new Person();
        person.setAge(1);
        try (FileOutputStream fos = new FileOutputStream("D:\\d\\a.txt");
             ObjectOutputStream oos = new ObjectOutputStream(fos)) {
            oos.writeObject(person);
            FileInputStream fis = new FileInputStream("D:\\d\\a.txt");
            ObjectInputStream ois = new ObjectInputStream(fis);
            return (Person) ois.readObject();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * unsafe创建
     * @return
     */
    public Person unsafe(){
        Field filed = null;
        try {
        	//获取unsafe实例
            filed = Unsafe.class.getDeclaredField("theUnsafe");
            filed.setAccessible(true);
            Unsafe unsafe = (Unsafe) filed.get(null);
            //分配一个Person实例，此处只分配内存，不会调用构造函数
            Person person = (Person) unsafe.allocateInstance(Person.class);
            return person;
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
            return null;
    }


}

class Person implements Cloneable, Serializable {
    private String name;
    private int age;

    public Person() {
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}