原型模式

原型模式概述

某些特定的时候，我们需要同一个类生成多个相同的对象，或者是基于一个对象生成一个复制对象，并再对复制对象进行修改，这时候就可以使用到原型模式。

UML

一个简单的示例：

package com.prototype;

public class Customer implements Cloneable {
	private String name;
	private int createYear;
	// 由于Address是引用对象, 所以address也需要实现clone方法,防止只实现了浅克隆
	private Address address;

	public String getName() {
		return name;
	}

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

	public int getCreateYear() {
		return createYear;
	}

	public void setCreateYear(int createYear) {
		this.createYear = createYear;
	}

	public Address getAddress() {
		return address;
	}

	public void setAddress(Address address) {
		this.address = address;
	}

	@Override
	protected Object clone() throws CloneNotSupportedException {
		Customer customer = new Customer();
		customer.setCreateYear(this.createYear);
		customer.setName(this.name);
		// 不应该使用这行代码,因为是引用对象,
		// 所以需要深克隆,否则Customerde克隆对象address的修改会影响被克隆对象的address
		// customer.setAddress(this.address);
		customer.setAddress((Address) this.address.clone());
		return customer;
	}

	@Override
	public String toString() {
		return "Customer [name=" + name + ", createYear=" + createYear
				+ ", address=" + address + "]";
	}

}

package com.prototype;

public class Address implements Cloneable {
	private String city;
	private String region;

	public Address(String city, String region) {
		super();
		this.city = city;
		this.region = region;
	}

	@Override
	protected Object clone() throws CloneNotSupportedException {
		Address address = new Address(this.city, this.region);
		return address;
	}

	public String getCity() {
		return city;
	}

	public void setCity(String city) {
		this.city = city;
	}

	public String getRegion() {
		return region;
	}

	public void setRegion(String region) {
		this.region = region;
	}

	@Override
	public String toString() {
		return "Address [city=" + city + ", region=" + region + "]";
	}
}

package com.prototype;

public class Client {
	public static void main(String[] args) throws CloneNotSupportedException {
		Customer customer1 = new Customer();
		customer1.setName("经销商A");
		customer1.setCreateYear(3);
		customer1.setAddress(new Address("Guangzhou", "tianhe"));
		Customer customer2 = (Customer) customer1.clone();
		customer2.setName("经销商B");
		// 大家可以试一下如果Address没有实现Cloneable接口和clone方法的话,会出现什么效果
		customer2.getAddress().setCity("Shenzhen");
		System.out.println(customer1);
		System.out.println(customer2);
	}
}

总结 

使用原型模式可以在不需要知道对象的创建细节的情况下，生成一个与原有对象相同的对象，不易出错且java给我们提供了Cloneable接口可以标记出该类是否支持克隆，但是这里又涉及了浅复制和深复制两种情况，在java中要实现深复制需要在被引用的类中再单独实现克隆方法，可能在这里就会比较繁琐。

才疏学浅，如文中有错误，感谢大家指出。