如何在jsp页面中显示servlet结果？

Question

我编写了一个简单的计数器 servlet 应用程序来显示访问页面的用户数量。我想在 jsp 页面中显示这个结果。但是我该怎么做呢？以下是我的代码...

public class ServerClass extends HttpServlet {
int counter = 0;
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
  PrintWriter out = response.getWriter();
int local_count;
synchronized(this) {
local_count = ++counter;
}
out.println("Since loading, this servlet has been accessed " +
        local_count + " times.");
out.close();
    }
}

Answer 1

您应该实现doGet（如果您提出POST 请求，则应该实现doPost）。除非从 normal servlet doXxx methods 之一调用，否则不会调用 processRequest。

通过请求属性公开变量：

// Convention would name the variable localCount, not local_count.
request.setAttribute("count", local_count);

转发到 JSP：

getServletContext()
    .getRequestDispatcher("/WEB-INF/showCount.jsp")
    .forward(request, response);

使用JSP EL（表达式语言）显示属性：

Since loading, this servlet has been accessed ${count} times.

如果本地计数变量未出现，请确保您的 web.xml 文件已配置为最新的 servlet 修订版。