面试题经常见到，就顺带整理下，创建对象的四种方式：
1.使用new创建对象
2.使用反射创建对象
3.使用clone创建对象
4.使用序列化反序列化创建对象
代码如下：
import java.io.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;/*** @Author: zhangximing* @Email: 530659058@qq.com* @Date: 2023/9/11 17:47* @Description: 创建对象四种方式*/
public class CreateObject {public static void main(String[] args) throws Exception {//1、new创建对象createByNew();//2、反射创建对象createByReflect("com.zhangximing.springbootinterceptor.object.MyObject");//3、clone创建对象（浅复制）createByClone();//4、序列化创建对象createBySer();}/*** new创建对象*/public static void createByNew(){MyObject myObject = new MyObject();myObject.create("new创建对象");}/*** 反射创建对象* @param classPathName* @throws Exception*/public static void createByReflect(String classPathName) throws Exception {Class c = Class.forName(classPathName);//无参构造方法创建对象Object object = c.newInstance();
// //有参构造器创建对象
// Constructor privateCon = c.getConstructor(String.class,MyObjectT.class);
// Object object1 = privateCon.newInstance("测试",new MyObjectT());//方法一：强转为指定对象调用方法MyObject myObject = (MyObject) object;String msg = "反射创建对象";myObject.create(msg);//方法二：指定方法以及参数进行调用Method executeMethod = c.getMethod("createT",String.class,Integer.class);Object result = executeMethod.invoke(object,msg,1);System.out.println("返回结果："+result);}/*** clone创建对象（注意对应类需要实现Cloneable）*/public static void createByClone(){MyObject myObject = new MyObject();
// MyObjectT myObjectT = new MyObjectT();
// myObjectT.setName("测试1");
// myObject.setMyObjectT(myObjectT);//浅拷贝：只拷贝对象本身，不拷贝引用对象MyObject myObjectClone = (MyObject) myObject.clone();myObjectClone.create("clone创建对象");}/*** 序列化创建对象（注意对应类需要实现Serializable）* 序列化：把Java对象转换为字节序列的过程。* 反序列化：把字节序列恢复为Java对象的过程。* @throws Exception*/public static void createBySer() throws Exception {File file = new File("myObject.txt");//序列化持久化对象ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(file));MyObject myObject = new MyObject("测试序列化",new MyObjectT("被引用对象"));out.writeObject(myObject);out.close();//反序列化，并得到对象ObjectInputStream in = new ObjectInputStream(new FileInputStream(file));// 没有强制转换类型Object object = in.readObject();in.close();System.out.println(object);}
}
import java.io.Serializable;/*** @Author: zhangximing* @Email: 530659058@qq.com* @Description: 对象*/
public class MyObject implements Cloneable, Serializable {private String name;private MyObjectT myObjectT;public MyObject(){}public MyObject(String name, MyObjectT myObjectT) {this.name = name;this.myObjectT = myObjectT;}public String getName() {return name;}public void setName(String name) {this.name = name;}public MyObjectT getMyObjectT() {return myObjectT;}public void setMyObjectT(MyObjectT myObjectT) {this.myObjectT = myObjectT;}public void create(String msg){System.out.println(msg);}public String createT(String msg,Integer i){return "已处理"+i+"，"+msg;}@Overridepublic MyObject clone() {//浅拷贝try {MyObject clone = (MyObject) super.clone();return clone;} catch (CloneNotSupportedException e) {throw new InternalError(e);}}@Overridepublic String toString() {return "MyObject{" +"name='" + name + '\'' +", myObjectT=" + myObjectT +'}';}
}
import java.io.Serializable;/*** @Author: zhangximing* @Email: 530659058@qq.com* @Description: 被引用对象（用于验证浅复制）*/
public class MyObjectT implements Serializable {private String name;public MyObjectT(){}public MyObjectT(String name){this.name = name;}public String getName() {return name;}public void setName(String name) {this.name = name;}@Overridepublic String toString() {return "MyObjectT{" +"name='" + name + '\'' +'}';}
}
)
)
