java创建对象的方式

2019-11-06 06:48:23

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java创建对象的方式

1、直接new2、通过反射clazz的newInstance调用无参构造函数创建对象3、通过反射获取构造函数直接newInstance创建对象4、实现Serializable接口，通过反系列化创建对象5、实现Cloneable接口，覆盖clone方法，通过克隆创建对象package cn.zlz.createobj;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.lang.reflect.Constructor;/** * 创建对象的方式 * 1、直接new * 2、通过反射clazz的newInstance调用无参构造函数创建对象 * 3、通过反射获取构造函数直接newInstance创建对象 * 4、实现Serializable接口，通过反系列化创建对象 * 5、实现Cloneable接口，覆盖clone方法，通过克隆创建对象 * */public class Main { public static void main(String[] args) { // 通过构造函数直接new Person person = new Person(); System.out.PRintln(person); // 通过反射创建对象 createByReflect(); // 通过构造器反射创建对象 createByConstructor(); // 通过序列化创建对象 createBySerialize(); //通过克隆创建对象 createByClone(); } private static void createByClone() { Person person = new Person("wangwu",5); Person clone = person.clone(); System.out.println(clone); } private static void createBySerialize() { try { String filePath = "person.dat"; Person instance = new Person("lizi",4); ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream( filePath)); objectOutputStream.writeObject(instance); ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(filePath)); Person person = (Person) objectInputStream.readObject(); System.out.println(person); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } private static void createByConstructor() { try { Class<?> clazz = Class.forName("cn.zlz.createobj.Person"); Constructor<?> constructor = clazz.getDeclaredConstructor(String.class, int.class); Person person = (Person) constructor.newInstance("zhangsan", 2); System.out.println(person); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } private static void createByReflect() { try { Class<?> clazz = Class.forName("cn.zlz.createobj.Person"); Person person = (Person) clazz.newInstance(); System.out.println(person); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }}package cn.zlz.createobj;import java.io.Serializable;public class Person implements Serializable, Cloneable { /** * */ private static final long serialVersionUID = 1L; private String name; private int age; public Person(String name, int age) { super(); this.name = name; this.age = age; } public Person() { super(); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; } @Override public Person clone() { Person person = null; try { return (Person) super.clone(); } catch (CloneNotSupportedException e) { e.printStackTrace(); } return person; }}

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