Servletcontext的应用---统计网站的访问次数

最新推荐文章于 2021-11-04 22:46:51 发布

原创最新推荐文章于 2021-11-04 22:46:51 发布 · 520 阅读

1 ·

CC 4.0 BY-SA版权

本文介绍了一个使用Java Servlet实现的历史访问计数器。该Servlet通过在ServletContext中存储和更新历史计数，来跟踪对特定资源的访问次数。文章详细展示了如何在用户请求时，同步地增加计数，并返回当前的访问次数。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

package lzh;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/history")
public class HistoryCountServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = getServletContext();
        synchronized (this){
            //第一次进来的时候没有数据，先get还是set?
            Integer historyCount = (Integer) servletContext.getAttribute("historyCount");
            if(historyCount==null){
                servletContext.setAttribute("historyCount",new Integer(1));
            }else{
                servletContext.setAttribute("historyCount",++historyCount);
            }
            response.getWriter().println("history count: "+ servletContext.getAttribute("historyCount"));

        }
    }
}