#1.==============配置檔案
bean.properties
#先寫dao，再寫service
UserDao=com.ghy.dao.impl.UserDaoImpl
UserService=com.ghy.service.impl.UserServiceImpl



#2.==============配置檔案

import java.util.Collections;
import java.util.Enumeration;
import java.util.LinkedHashSet;
import java.util.Properties;
import java.util.Set;

/**
 * @author ghy
 * @version 1.0
 * @date 2021-09-13
 * @userd 使得Properties有序
 */
public class OrderedProperties extends Properties {

    private static final long serialVersionUID = 4710927773256743817L;

    private final LinkedHashSet<Object> keys = new LinkedHashSet<Object>();

    @Override
    public Enumeration<Object> keys() {
        return Collections.<Object> enumeration(keys);
    }

    @Override
    public Object put(Object key, Object value) {
        keys.add(key);
        return super.put(key, value);
    }

    @Override
    public Set<Object> keySet() {
        return keys;
    }

    /**
     * 返回按照properties檔案儲存順序的名稱集合
     * @return
     */
    @Override
    public Set<String> stringPropertyNames() {
        Set<String> set = new LinkedHashSet<String>();

        for (Object key : this.keys) {
            set.add((String) key);
        }

        return set;
    }
}




#3.==============BeanFctory

import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

/**
 * Spring bean 工廠模式開發
 * @author ghy
 * @version 1.0
 * @date 2021-12-28
 **/
public class BeanFactory {

    private static Map<String, Object> ioc = new HashMap<>();
    private static Properties properties = new OrderedProperties();

    static {
        try {
            properties.load(BeanFactory.class.getClassLoader().getResourceAsStream("bean.properties"));
            //beanNames : 是無序的
            Set<String> beanNames = properties.stringPropertyNames();
            for (String beanName : beanNames) {
                if(null != beanName && !beanName.trim().equals("")) {
                    Class<?> clazz = Class.forName(properties.getProperty(beanName));
                    if(null != clazz) {
                        Object instance = clazz.newInstance();
                        if(null != instance) {
                            ioc.put(beanName, instance);
                        }
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static Object getBean(String beanName){
        return ioc.get(beanName);
    }

}