原型模式简介
- 模式属于创立型模式，它提供了一种创建对象的最佳形式。
- 用于创立反复的对象，同时又能保障性能。
- 这种模式是实现了一个原型接口，该接口用于创立以后对象的克隆。当间接创建对象的代价比拟大时，则采纳这种模式。
- 例如，一个对象须要在一个高代价的数据库操作之后被创立。咱们能够缓存该对象，在下一个申请时返回它的克隆，在须要的时候更新数据库，以此来缩小数据库调用。
浅克隆
类Book实现Cloneable接口并重写clone办法
public class Book implements Cloneable { private String name;//书名 private Date publishDate;//公布日期 public Book() { } public Book(String name, Date publishDate) { this.name = name; this.publishDate = publishDate; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getPublishDate() { return publishDate; } public void setPublishDate(Date publishDate) { this.publishDate = publishDate; } @Override protected Object clone() throws CloneNotSupportedException { return super.clone(); } @Override public String toString() { return "Book{" + "name='" + name + '\'' + ", publishDate=" + publishDate + '}'; }}
测试类
public class Test { public static void main(String[] args) throws CloneNotSupportedException { String name = "Java 设计模式"; Date publishDate = new Date(); Book book = new Book(name, publishDate); //克隆出对象 Book clone = (Book) book.clone(); System.out.println(book); System.out.println(book.hashCode()); System.out.println(clone); System.out.println(clone.hashCode()); System.out.println("=================="); publishDate.setTime(publishDate.getTime() + 2000);//批改工夫 System.out.println(book); System.out.println(book.hashCode()); System.out.println(clone); System.out.println(clone.hashCode()); /** * 测试后果：批改了工夫，源对象和克隆的对象的工夫，都产生了扭转 * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:33 CST 2021} * 2093631819 * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:33 CST 2021} * 2074407503 * ================== * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:35 CST 2021} * 2093631819 * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:35 CST 2021} * 2074407503 */ }}
测试后果
Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:33 CST 2021}2093631819Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:33 CST 2021}2074407503==================Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:35 CST 2021}2093631819Book{name='Java 设计模式', publishDate=Wed Dec 29 12:17:35 CST 2021}2074407503
深克隆
类Book实现Cloneable接口并重写clone办法
public class Book implements Cloneable { private String name;//书名 private Date publishDate;//公布日期 public Book() { } public Book(String name, Date publishDate) { this.name = name; this.publishDate = publishDate; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getPublishDate() { return publishDate; } public void setPublishDate(Date publishDate) { this.publishDate = publishDate; } @Override protected Object clone() throws CloneNotSupportedException { Object obj = super.clone(); Book book = (Book) obj; //将源对象的属性也进行克隆，即深克隆 book.publishDate = (Date) book.publishDate.clone(); return obj; } @Override public String toString() { return "Book{" + "name='" + name + '\'' + ", publishDate=" + publishDate + '}'; }}
测试类
public class Test { public static void main(String[] args) throws CloneNotSupportedException { String name = "Java 设计模式"; Date publishDate = new Date(); Book book = new Book(name, publishDate); //克隆出对象 Book clone = (Book) book.clone(); System.out.println(book); System.out.println(book.hashCode()); System.out.println(clone); System.out.println(clone.hashCode()); System.out.println("=================="); publishDate.setTime(publishDate.getTime() + 2000); System.out.println(book); System.out.println(book.hashCode()); System.out.println(clone); System.out.println(clone.hashCode()); /** * 测试后果：批改了工夫，源对象的工夫，产生了扭转，但克隆的对象的工夫没有扭转 * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:47 CST 2021} * 2093631819 * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:47 CST 2021} * 2074407503 * ================== * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:49 CST 2021} * 2093631819 * Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:47 CST 2021} * 2074407503 */ }}
测试后果
Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:47 CST 2021}2093631819Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:47 CST 2021}2074407503==================Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:49 CST 2021}2093631819Book{name='Java 设计模式', publishDate=Wed Dec 29 12:41:47 CST 2021}2074407503