Java创建对象的四种方式

四种方式：

1. new创建对象
2. 反射机制创建对象
3. 克隆创建对象
4. 反序列化创建对象

直接上实操代码：

Preson实体类

package com.bean;

import java.io.Serializable;

public class Person implements Cloneable, Serializable {
    String name;
    Integer age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

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

    public Person(String name, Integer age) {
        this.name = name;
        this.age = age;
    }
    public Person(){

    }

    @Override
    public Person clone() throws CloneNotSupportedException {
        return (Person) super.clone();
    }

    @Override
    public String toString() {
        return "{name:"+this.name+",age:"+this.age+"}";
    }
}

测试代码：

package com.company;

import com.bean.*;
import com.sun.javafx.util.Utils;
import com.sun.xml.internal.messaging.saaj.util.ByteInputStream;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Constructor;


public class Main {

    public static void main(String[] args) throws Exception {

        //new创建对象
        Person person = new Person("张三", 15);
        //反射机制创建对象
        Constructor<?>[] constructors = Person.class.getDeclaredConstructors();
        Constructor<?> haveArgsConstructor = constructors[1];
        Object reflectPerson = haveArgsConstructor.newInstance("张三", 15);
        System.out.println(reflectPerson);
        System.out.println(person == reflectPerson);
        //clone创建对象
        Person copyPerson = person.clone();
        System.out.println(copyPerson);
        System.out.println(person == copyPerson);
        //序列化创建对象
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(bos);
        oos.writeObject(person);
        ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
        ObjectInputStream ois = new ObjectInputStream(bis);
        Object serializedPerson = ois.readObject();
        System.out.println(serializedPerson);
        System.out.println(person == serializedPerson);
    }
}

运行结果：

{name:张三,age:19}
false
{name:张三,age:15}
false
{name:张三,age:15}
false

总结：

创建对象不一定需要调用构造函数，clone创建和反序列化创建就没有用到构造函数。