package com.youai;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class Factory {
    public static final String Tag = Factory.class.getSimpleName();
    final static Map<String, Object> factory = new ConcurrentHashMap<>();

    public static <T> Object getFactory(Class<T> clazz) {
        Object object 
 
= null;
        if (factory.containsKey(clazz.getSimpleName())) {
            System.err.println("直接獲取：" + clazz.getSimpleName());
            return factory.get(clazz.getSimpleName());
        }
        try {
            object = clazz.newInstance();
            factory.put(clazz.getSimpleName(), object);
            System.err.println(
 
"初始化：" + clazz.getSimpleName());
            return object;
        } catch (InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        }
        return object;
    }

    public static void main(String[] args) throws Exception {
        Test();
        Thread.sleep(
 
10000);
        Test();
    }

    public static void Test() {
        Send send = (Send) getFactory(Send.class);
        send.run();
        Message message = (Message) getFactory(Message.class);
        message.run();
        Back back = (Back) getFactory(Back.class);
        back.run();
    }

}

class Send {
    public static final String Tag = Send.class.getSimpleName();

    public Send() {

    }

    public void run() {
        for (int k = 0; k < 10; k++) {
            System.err.println(Send.Tag);
        }
    }

}

class Message {
    public static final String Tag = Message.class.getSimpleName();

    public Message() {

    }

    public void run() {
        for (int k = 0; k < 10; k++) {
            System.err.println(Message.Tag);

        }
    }
}

class Back {
    public static final String Tag = Back.class.getSimpleName();

    public Back() {

    }

    public void run() {
        for (int k = 0; k < 10; k++) {
            System.err.println(Back.Tag);

        }
    }
}

執行：
初始化：Send
Send
Send
Send
Send
Send
Send
Send
Send
Send
Send
初始化：Message
Message
Message
Message
Message
Message
Message
Message
Message
Message
Message
初始化：Back
Back
Back
Back
Back
Back
Back
Back
Back
Back
Back
直接獲取：Send
Send
Send
Send
Send
Send
Send
Send
Send
Send
Send
直接獲取：Message
Message
Message
Message
Message
Message
Message
Message
Message
Message
Message
直接獲取：Back
Back
Back
Back
Back
Back
Back
Back
Back
Back
Back