老师，如果将控制器全部改写为单例模式，构造方法私有然后提供一个获取实例的方法，那么GlobalController中反射部分使用newInstance()方法创建控制器对象的过程会受到影响吗？控制器改写为单例模式后原有的GlobalController能直接使用吗？还是说需要做一些修改呢？

package com.imooc.icake.global;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class GlobalController extends GenericServlet {
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        HttpServletRequest request= (HttpServletRequest) servletRequest;
        HttpServletResponse response= (HttpServletResponse) servletResponse;
        String path= request.getServletPath();
        if(path.indexOf("/admin")!=-1){
            path=path.substring(7);
        }else{
            path=path.substring(1);
        }
        int index=path.indexOf("/");
        String className="com.imooc.icake.controller.";
        String methodName=null;
        if(index!=-1){
            className=className+path.substring(0,index)+"Controller";
            methodName=path.substring(index+1,path.indexOf(".do"));
        }else{
            className=className+"DefaultController";
            methodName=path.substring(0,path.indexOf(".do"));
        }
        try {
            Class clazz=Class.forName(className);
            Object object=clazz.newInstance();
            Method method=clazz.getMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);
            method.invoke(object,request,response);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
}

​