工厂模式和单例模式

工厂模式

public class Factory_1 {
    public static void main(String[] args) {

        //普通方法实现
        C1 c01 = new Simple_factory().make("AAA");
        if(!c01.equals(null)){
            c01.build();
        }
        C1 c02 = new Simple_factory().make("BBB");
        if(!c02.equals(null)){
            c02.build();
        }
        C1 c03 = new Simple_factory().make("CCC");
        System.out.println(c03==null);

        //通过反射的方式实现
        C1 c04 = new Simple_factory_1().make(BBB.class);
        c04.build();
        C1 c05 = new Simple_factory_1().make(AAA.class);
        c05.build();
    }
}

//创建接口C1
interface C1{
    void build();
}
//创建类BBB实现接口C1
class BBB implements C1{
    @Override
    public void build() {
        System.out.println("BBBBBBBBBBBBBBBB");
    }
}
//创建类AAA实现接口C1
class AAA implements C1{
    @Override
    public void build() {
        System.out.println("AAAAAAA");
    }
}
//创建工厂，注意返回的是”接口C1“或者null
class Simple_factory{
    public static C1 make(String str){
        if("AAA".equals(str)){
            return new AAA();
        }else if("BBB".equals(str)){
            return new BBB();
        }else {
            System.out.println("无法生产");
            return null;
        }
    }
}
//创建反射工厂，传入Class，获得对象
class Simple_factory_1{
    public static C1 make(Class c)  {
        C1 c1 = null;
        try {
            c1 =(C1) Class.forName(c.getName()).newInstance();//根据类名获得类，然后再实例化处一个对象
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return c1;
    }
}

 

单例模式：

//懒汉模式（线程不安全）
class single_01{
    private static single_01 single_01;
    public static single_01 getInstance(){
        if(single_01==null){
            single_01 = new single_01();
        }
        return single_01;
    }
}
//懒汉模式（线程安全）
class single_02{
    private static single_01 single_01;
    public static synchronized single_01 getInstance(){
        if(single_01==null){
            single_01 = new single_01();
        }
        return single_01;
    }
}
//饿汉模式
class single_03{
    private static single_03 s = new single_03();
    public static synchronized single_03 getInstance(){
        return s;
    }
}
//静态内部类
class single_04{
    private static class xxxx{
        private static final single_04 s4 = new single_04();
    }
    private single_04(){}
    public static final single_04 getInstance(){
        return xxxx.s4;
    }
}