java设计模式--原型模式
2020-12-13 04:02
标签：com tco 缺点 get 复制 重写 clone() row 循环 原型模式：用原型实例指定创建对象的种类，并通过拷贝这些原型创建新的对象。通俗来说就是克隆一个对象，而且不用知道创建对象的细节，然后对这个对象进行自定义操作。首先，我们先看一下下面的这个例子。 得到的结果为： name:zhangsan,age:23,genderman name:zhangsan,age:25,genderwoman name:zhangsan,age:26,genderman 我们可以看到值类型的字段都会拷贝一份新的出来，对他们修改也不会对被克隆对象的值进行修改，但是如果字段是引用类型，则拷贝引用，但不复制引用的对象，这样的话如果我们对引用类型的字段company进行修改就会导致显示的永远是最后一次修改的值，因为拷贝出的三个引用指向一个对象，这就是浅拷贝。 那么如果我们想把引用类型的字段也拷贝一份出来呢，那么我们就需要把引用类型也实现Cloneable接口，并重写Clone()方法，并且把引用类型的属性再拷贝一遍，代码如下： 结果为： name:zhangsan,age:23,genderman name:zhangsan,age:25,genderwoman name:zhangsan,age:26,genderman 我们可以看到对复制出的对象中的引用对象company赋值时，并没有改变原型对象，因为引用对象的变量指向了新的克隆出的对象，这就是深拷贝。 总结：原型模式的优点就是可以快速创建对象，比直接new一个对象再进行赋值的操作性能要好，缺点就是每个类都得实现克隆方法，当有多层引用时，需要考虑是否会造成引用死循环。 java设计模式--原型模式 标签：com tco 缺点 get 复制 重写 clone() row 循环 原文地址：https://www.cnblogs.com/yimengyizhen/p/11102435.html//公司类
public class Company {
private String level;
private Long workYears;
public String getLevel() {
return level;
}
public void setLevel(String level) {
this.level = level;
}
public Long getWorkYears() {
return workYears;
}
public void setWorkYears(Long workYears) {
this.workYears = workYears;
}
}
//实现Cloneable接口的People类（原型实例）
public class People implements Cloneable {
private String name;
private Long age;
private String gender;
//公司属性，没有实现Cloneable接口
private Company company;
public String getName() {
return name;
}
public People() {
//在初始People类的同时创建company实例
this.company = new Company();
}
public void setName(String name) {
this.name = name;
}
public Long getAge() {
return age;
}
public void setAge(Long age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public Company getCompany() {
return company;
}
public void setCompany(String level,Long workYears) {
//给company的属性赋值
this.company.setLevel(level);
this.company.setWorkYears(workYears);
}
//Clone()方法，clone people类
public Object Clone() {
Object clone = null;
try {
clone = super.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
return (People) clone;
}
public void show() {
System.out.println("name:" + name + ",age:" + age + ",gender" + gender);
System.out.println("name:" + name + ",level:" + company.getLevel() + ",workYears:" + company.getWorkYears());
}
}
public class Test {
public static void main(String[] args) {
//原型实例对象
People people = new People();
people.setName("zhangsan");
people.setAge(23L);
people.setGender("man");
people.setCompany("A7",3L);
//克隆对象1，修改age，gender属性
People clone1 = (People)people.Clone();
clone1.setAge(25L);
clone1.setGender("woman");
//克隆对象2，修改age，company属性
People clone2 = (People)people.Clone();
clone2.setAge(26L);
clone2.setCompany("A8",4L);
people.show();
clone1.show();
clone2.show();
}
}
name:zhangsan,level:A8,workYears:4
name:zhangsan,level:A8,workYears:4
name:zhangsan,level:A8,workYears:4public class Company implements Cloneable{
private String level;
private Long workYears;
public String getLevel() {
return level;
}
public void setLevel(String level) {
this.level = level;
}
public Long getWorkYears() {
return workYears;
}
public void setWorkYears(Long workYears) {
this.workYears = workYears;
}
//Clone()方法，clone company类
public Object Clone() {
Object clone = null;
try {
clone = super.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
return clone;
}
}
//实现Cloneable接口的People类
public class People implements Cloneable {
private String name;
private Long age;
private String gender;
private Company company;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public People() {
//在给People赋name的同时创建company实例
this.company = new Company();
}
public People(Company company) {
this.company = (Company) company.Clone();
}
public Long getAge() {
return age;
}
public void setAge(Long age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public Company getCompany() {
return company;
}
public void setCompany(String level, Long workYears) {
//给company的属性赋值
this.company.setLevel(level);
this.company.setWorkYears(workYears);
}
//Clone()方法，clone people类
public Object Clone() {
Object object = null;
try {
object = super.clone();
//把引用类型company再拷贝一遍
((People)object).company = (Company) this.company.Clone();
} catch (CloneNotSupportedException exception) {
throw new RuntimeException(exception);
}
return object;
}
public void show() {
System.out.println("name:" + name + ",age:" + age + ",gender" + gender);
System.out.println("name:" + name + ",level:" + company.getLevel() + ",workYears:" + company.getWorkYears());
}
}
name:zhangsan,level:A7,workYears:3
name:zhangsan,level:A7,workYears:3
name:zhangsan,level:A8,workYears:4