设计模式GOF23（创建型模式）

package com.bjsxt.design;public class SingletonDemo1 {
//类初始化就加载这个对象，因为类初始化就加载了所以线程是安全的
private static SingletonDemo1 instance=new SingletonDemo1(); private SingletonDemo1(){} //方法不需要同步，效率高
public static SingletonDemo1 getInstance(){
return instance;
}
}


package com.bjsxt.design;public class Client {
public static void main(String[] args) {
SingletonDemo1 demo1=SingletonDemo1.getInstance();
SingletonDemo1 demo11=SingletonDemo1.getInstance();
System.out.println(demo1==demo11); }
}


true表示俩者地址一样

package com.bjsxt.design;import java.io.ObjectStreamException;/**
* 防止反射的反序列化
*/
public class SingletonDemo6 {
//类初始化就加载这个对象，因为类初始化就加载了所以线程是安全的
private static SingletonDemo6 instance=new SingletonDemo6(); private SingletonDemo6(){
//阻止反射调用
if (instance!=null){
throw new RuntimeException();
}
} //阻止通过反序列化
private Object readResolve() throws ObjectStreamException{
return instance;
} //方法不需要同步，效率高
public static SingletonDemo6 getInstance(){
return instance;
}
}


package com.bjsxt.design;public enum SingletonDemo5 {
Insatnce; public void SingletonOperation(){
}
}


package com.bjsxt.factory;public class CarFactory { public static Car createCar(String type){ Car car=null;
if ("奔驰".equals(type)){
car=new BenChi();
}else if("宝马".equals(type)){
car=new BMW();
}
return car;
}
}


package com.bjsxt.factory;public class CarFactory2 {
public static Car createBMW(){
return new BMW();
} public static Car createBenChi(){
return new BenChi();
}
}