定义
抽象工厂模式提供一个创建一系列相关或相互依赖对象的接口，而无需指定它们具体的类
角色
- 抽象产品类A
- 抽象产品类B
- 抽象工厂类
- 具体工厂类C（生成A）
- 具体工厂类D（生产B）
UML类图
抽象工厂模式UML类图
代码
- IBenz.java
public interface IBenz {
void run();
}
- IBWM.java
public interface IBWM {
void run();
}
- HomeUseBenz.java
public class HomeUseBenz implements IBenz {
@Override
public void run() {
System.out.println("first.HomeUseBenz run");
}
}
- HomeUseBWM.java
public class HomeUseBWM implements IBWM {
@Override
public void run() {
System.out.println("first.HomeUseBWM run");
}
}
- BusinessUseBenz.java
public class BusinessUseBenz implements IBenz {
@Override
public void run() {
System.out.println("first.BusinessUseBenz run");
}
}
- BusinessUseBWM.java
public class BusinessUseBWM implements IBWM {
@Override
public void run() {
System.out.println("first.BusinessUseBWM run");
}
}
- AbstarctFactory.java
public abstract class AbstarctFactory {
public abstract IBWM createBWM();
public abstract IBenz createBenz();
}
- HomeUseFactory.java
public class HomeUseFactory extends AbstarctFactory {
@Override
public IBWM createBWM() {
return new HomeUseBWM();
}
@Override
public IBenz createBenz() {
return new HomeUseBenz();
}
}
- BusinessFactory.java
public class BusinessFactory extends AbstarctFactory {
@Override
public IBWM createBWM() {
return new BusinessUseBWM();
}
@Override
public IBenz createBenz() {
return new BusinessUseBenz();
}
}
抽象工厂模式的优点
- 1 易于交换产品系列，由于具体工厂类，在一个应用中只需要在初始化的时候出现一次，这就使得改变一个应用的具体工厂变得非常容易，它只需要改变具体工厂即可使用不同的产品配置
- 2 它让具体的创建实例的过程与客户端分离，客户端是通过它们的抽象接口操作实例，产品的具体类名也被具体工厂的实现分离，不会出现在客户代码中
抽象工厂模式的缺点
如果想要增加一个不同的车型，则需要增加三个类以及修改三个工厂，比较繁琐！
使用简单工厂改进抽象工厂
UML类图
简单工厂改进抽象工厂UML.png
代码
- AllFactory.java
public class AllFactory {
private static final String type = "home";
//private static final String type = "business";
public static IBenz createBenz(){
IBenz benz = null;
switch (type){
case "home":
benz = new HomeUseBenz();
break;
case "business":
benz = new BusinessUseBenz();
break;
}
return benz;
}
public static IBWM createBWM(){
IBWM bwm = null;
switch (type){
case "home":
bwm = new HomeUseBWM();
break;
case "business":
bwm = new BusinessUseBWM();
break;
}
return bwm;
}
}
使用反射改进抽象工厂方法
public class AllFactory {
private final static String type="homeUse";
//private final static String type="businessUse";
public static IBenz createBenz() throws ClassNotFoundException, IllegalAccessException, InstantiationException {
String className = type.substring(0, 1).toUpperCase() + type.substring(1) + "Benz";
//获取包路径
String packageName = new Object() {
public String getPackageName() {
return this.getClass().getPackage().getName();
}
}.getPackageName();
Class<? extends IBenz> clazz = (Class<? extends IBenz>) Class.forName(packageName+"."+className);
return clazz.newInstance();
}
public static IBWM createBWM() throws IllegalAccessException, InstantiationException, ClassNotFoundException {
String className = type.substring(0, 1).toUpperCase() + type.substring(1) + "BWM";
//获取包路径
String packageName = new Object() {
public String getPackageName() {
return this.getClass().getPackage().getName();
}
}.getPackageName();
Class<? extends IBWM> clazz = (Class<? extends IBWM>) Class.forName(packageName +"."+className);
return clazz.newInstance();
}
}
