Java 创建对象的几种方式

平时每次用到对象的时候都是去new，好像也没什么别的方式了。

后来查了下，java创建对象有好多种方式：

先写一个POJO；

package com.bizi.core;
public class User {
	private String username = "bizi";
	private String password = "pass";
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}

1.调用构造方法创建对象：

@Test
public void testNew(){
	User user = new User();
	System.out.println(user.getUsername());
}

2.使用反射的方式创建对象：

@Test
public void testReflect() throws ClassNotFoundException, IllegalAccessException, InstantiationException {
	Class clazz = Class.forName(User.class.getName());
	Object object = clazz.newInstance();
	if(object instanceof User){
		User user = (User)object;
		System.out.println(user.getPassword());
	}
}

3.使用对象的clone（）的方法:

源始类需要实现Cloneable：

package com.bizi.core;
public class User implements Cloneable{
	private String username = "bizi";
	private String password = "pass";
	public Object clone()throws CloneNotSupportedException{
		return super.clone();
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}

@Test
public void testClone() throws CloneNotSupportedException {
	User user1 = new User();
	User user2 = (User) user1.clone();
	user1.setPassword("new password");
	System.out.println(user2.getPassword());
}

4.使用反序列化机制：

@Test
public void testSerializable() throws IOException, ClassNotFoundException {
	User user = new User();
	String file = "C:/User.txt";
	ObjectOutputStream oo = new ObjectOutputStream(new FileOutputStream(new File(file)));
	oo.writeObject(user);
	oo.close();
	ObjectInputStream ois = new ObjectInputStream(new FileInputStream(new File(file)));
	User newUser = (User) ois.readObject();
	ois.close();

	System.out.println(newUser == user);
	System.out.println(newUser.getPassword());
}

来自为知笔记(Wiz)