工厂模式

#工厂
package com.spring.base;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

public class ServiceFactory {

    private static final String CONF_FILE_NAME="conf.properties";

    private static  Properties prop;

    private static Map<String,Object> beanContainer;
    //静态代码块作用：每次初始化这个类时只加载配置文件
    static {
        try {
            beanContainer=new HashMap<>();
            prop=new Properties();
            prop.load(ServiceFactory.class.getClassLoader().getResourceAsStream(CONF_FILE_NAME));
        } catch (IOException e) {
//            e.printStackTrace();
            throw  new IllegalArgumentException(e);
        }
    }

    public static <T> T getService(Class<T> clazz){
        //增加配置文件中key-value的缓存，多次调用同一个key时，不需要再重新使用反射
        if (beanContainer.containsKey(clazz.getSimpleName())) {
            return (T) beanContainer.get(clazz.getSimpleName());
        }

        try {
            String className = prop.getProperty(clazz.getSimpleName());
            Class<?> obj = Class.forName(className);
            beanContainer.put(clazz.getSimpleName(), obj);
            return (T) obj.newInstance();
//            System.out.println("++++"+className);
        }  catch (Exception e) {
            throw  new IllegalArgumentException(e);
        }
    }
    public static void main(String[] args) {
        getService(AccountService.class);
    }
}



　　

#具体接口和实现类
package com.spring.base;

public interface AccountService {



    void insetAccout(String msg);
}

　　

package com.spring.base.impl;

import com.spring.base.AccountService;

public class AccountServiceImpl implements AccountService {
    @Override
    public void insetAccout(String msg) {
        System.out.println("=====AccountService==="+msg);;
    }
}

　调用入口:　

package com.spring.base;

public class App {


    public static void main(String[] args) {

        ServiceFactory serviceFactory=new ServiceFactory();

        AccountService accountService1=serviceFactory.getService(AccountService.class);
        accountService1.insetAccout("666");
        AccountService accountservice2=serviceFactory.getService(AccountService.class);
        accountservice2.insetAccout("777");


    }
}

　　配置文件：

AccountService=com.spring.base.impl.AccountServiceImpl