Filter小应用/ 动态jsp页面不缓存，静态文件缓存，Firefox如何去查看和清除缓存

程序员文章站 2022-05-23 08:38:22

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前言

今天学习了Filter的小作用，这个缓存还是比较重要的一门技术，能够加快你网页的访问。往往动态的jsp页面，是不需要缓存的，一个动态的玩意儿你缓存了干嘛。但是往往那些持久的，不变的静态资源你需要进行缓存。这样可以加快浏览器的访问速度。

代码

缓存静态资源:

@WebFilter(filterName = "StaticCachedFilter")
public class StaticCachedFilter implements Filter {

    private FilterConfig config = null;

    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        //1.获取用户想访问的资源
        String uri = request.getRequestURI();
        //2.得到后缀名和配置文件项进行匹配
        String ext = uri.substring(uri.lastIndexOf(".") + 1);
        //3.设置缓存的时间
        String time = config.getInitParameter(ext);

        if (time != null) {
            long time1 = Long.parseLong(time) * 3600 * 1000;
            response.setDateHeader("Expires", System.currentTimeMillis() + time1);
        }

        chain.doFilter(req, resp);
    }

    public void init(FilterConfig config) throws ServletException {
        this.config = config;
    }

动态jsp不缓存.

@WebFilter(filterName = "NoCacheFilter", urlPatterns = {"*.jsp"})
public class NoCacheFilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        HttpServletResponse response = (HttpServletResponse) resp;
        HttpServletRequest request = (HttpServletRequest) req;

        response.setDateHeader("Expires", -1);
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");
        chain.doFilter(request, response);
    }

    public void init(FilterConfig config) throws ServletException {

    }

}