我正在阅读“傻瓜设计模式”。我阅读并实践了装饰者模式。使用装饰器模式,我们可以用任何东西装饰一个对象。现在,我想在装饰之前删除装饰对象。我已经通过 ArrayList 解决了这个问题,但我仍然觉得它不好。你能告诉我如何移除装饰过的物体吗?什么是更好的方法?
这是我的方式:
计算机.java
public class Computer {
public Computer() {
}
public String description() {
return "computer";
}
}
ComponentDecorator.java
public abstract class ComponentDecorator extends Computer {
@Override
public abstract String description();
}
CD.java
public class CD extends ComponentDecorator {
private Computer computer;
public CD() {
}
public CD(Computer computer) {
this.computer = computer;
}
@Override
public String description() {
return computer.description() + " and a CD";
}
}
磁盘.java
public class Disk extends ComponentDecorator {
private Computer computer;
public Disk() {
}
public Disk(Computer c) {
computer = c;
}
@Override
public String description() {
return computer.description() + " and a disk";
}
}
Monitor.java
public class Monitor extends ComponentDecorator {
private Computer computer;
public Monitor() {
}
public Monitor(Computer computer) {
this.computer = computer;
}
@Override
public String description() {
return computer.description() + " and a monitor";
}
}
主.java
import java.util.ArrayList;
import java.util.Arrays;
public class Main {
static ArrayList<ComponentDecorator> list = new ArrayList<>();
public static void main(String[] args) {
addComponent(new CD(), new Disk(), new Monitor());
System.out.println(list.size());
Computer penIII = getComputer();
removeComponent(new Monitor());
penIII = getComputer();
System.out.println(penIII.description());
}
private static void addComponent(ComponentDecorator... comp) {
list.addAll(Arrays.asList(comp));
}
private static void removeComponent(ComponentDecorator comp) {
for(ComponentDecorator c : list) {
if(c.getClass() == comp.getClass()) {
list.remove(list.indexOf(c));
break;
}
}
}
private static Computer getComputer() {
Computer c = new Computer();
Class e;
for(ComponentDecorator d : list) {
e = d.getClass();
try {
c = (Computer) e.getConstructor(new Class[]{Computer.class}).newInstance(c);
} catch(Exception ex) {
ex.printStackTrace();
}
}
return c;
}
}
最佳答案
更好的方法是将“removeDecorator”方法添加到您的 ComponentDecorator 类。
public abstract class ComponentDecorator {
private ComponentDecorator subject;
public ComponentDecorator(ComponentDecorator subject) {
this.subject = subject;
}
@Override
public abstract String description();
}
public void removeDecorator(ComponentDecorator toRemove) {
if (subject == null) {
return;
} else if (subject.equals(toRemove)) {
subject = subject.getSubject();
} else {
subject.removeDecorator(toRemove);
}
}
public ComponentDecorator getSubject() {
return subject;
}
// Computer
public class Computer extends ComponentDecorator{
public Computer() {
super(null);
}
public String description() {
return "computer";
}
// CD
public class CD extends ComponentDecorator {
public CD(ComponentDecorator computer) {
super(computer);
}
@Override
public String description() {
return getSubject().description() + " and a CD";
}
}
// main
public static void main(String[] args) {
ComponentDecorator penIII = new Computer();
penIII = new CD(penIII);
penIII = new Monitor(penIII);
System.out.println(penIII.description());
}
如果您没有要删除的装饰器的引用,您可以创建另一个类的方法。
但是,您需要将装饰对象设置为“ComponentDecorator”而不是“Computer”。我建议让 Computer 类扩展 ComponentDecorator,而不是相反。
关于java - 如何从 Java 中的装饰器模式中删除装饰对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12239784/