spring-webmvc-5.1.7.RELEASE中HandlerInterceptor接口不重写方法不报错

博客对比了spring-webmvc-5.1.7.RELEASE和旧版本4.3.7中HandlerInterceptor接口。指出在新版本实现该接口时，不重写方法不会报错，原因是有default修饰。

对比源码

spring-webmvc-5.1.7.RELEASE中HandlerInterceptor接口

package org.springframework.web.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.lang.Nullable;

public interface HandlerInterceptor {
    default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return true;
    }

    default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
    }

    default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
    }
}

与旧版本4.3.7比较：

package org.springframework.web.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public interface HandlerInterceptor {
    boolean preHandle(HttpServletRequest var1, HttpServletResponse var2, Object var3) throws Exception;

    void postHandle(HttpServletRequest var1, HttpServletResponse var2, Object var3, ModelAndView var4) throws Exception;

    void afterCompletion(HttpServletRequest var1, HttpServletResponse var2, Object var3, Exception var4) throws Exception;
}

这是为什么新版本实现HandlerInterceptor 接口时，不重写方法也不会报错，因为有default修饰；