JavaWeb_创建HttpFilter

Dear 丶 2023-08-17 17:41 93阅读 0赞

package com.demo.filter;
    
    import javax.servlet.*;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    /**
     * 自定义HttpFilter，实现Filter接口
     */
    public abstract class HttpFilter implements Filter {
    
        //用于保存filterConfig对象
        private FilterConfig filterConfig;
    
        /**
         * 不建议子类直接覆盖，若直接覆盖，有可能会导致filterConfig成员变量初始化失败
         * @param filterConfig
         * @throws ServletException
         */
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            this.filterConfig = filterConfig;
            init();
        }
    
        /**
         * 供子类继承的初始化方法，可以通过getFilterConfig()获取FilterConfig对象
         */
        protected void init() {
        }
    
        /**
         * 直接返回init(ServletConfig)的FilterConfig对象
         * @return
         */
    
        public FilterConfig getFilterConfig() {
            return filterConfig;
        }
    
        /**
         * 原生的doFilter方法，在方法内部把ServletRequest和ServletResponse
         * 转为了HttpServletRequest和HttpServeltResponse，并调用了doFilter(HttpServletResponse response, HttpServletRequest request,FilterChain filterChain)
         * @param servletRequest
         * @param servletResponse
         * @param filterChain
         * @throws IOException
         * @throws ServletException
         */
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            HttpServletRequest request = (HttpServletRequest) servletRequest;
            HttpServletResponse response = (HttpServletResponse) servletResponse;
            doFilter(request,response,filterChain);
        }
        //抽象方法，为Http请求定制，必须实现的方法
        public abstract void doFilter(HttpServletResponse response, HttpServletRequest request,FilterChain filterChain) throws IOException, ServletException;
    
        @Override
        public void destroy() {}
    }

转载于:https://www.cnblogs.com/yangHS/p/11195291.html