16 域对象2 Request域

落日映苍穹つ 2023-09-27 15:58 140阅读 0赞

4.1 Request域

有效范围

一次请求内有效,请求转发时数据可以传递,除此之外该域没有办法实现数据共享

生命周期

创建 每发生一次请求创建一个独立的请求域

使用service方法中或者请求转发有效

销毁 请求结束,已经向浏览器响应数据

测试代码

向request域中放入数据

package com.msb.testRequest;
    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;
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.List;
    /**
     * @Author: Ma HaiYang
     * @Description: MircoMessage:Mark_7001
     */
    @WebServlet(urlPatterns = "/addToRequest.do")
    public class Servlet1 extends HttpServlet {
        @Override
        protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            // 向request域中添加数据
            List<String> x=new ArrayList<>();
            Collections.addAll(x, "a","b","c");
            req.setAttribute("list", x);
            req.setAttribute("gender","boy");
            req.setAttribute("gender","girl");
            req.setAttribute("name","晓明");
            // 请求转发
             req.getRequestDispatcher("/readFromRequest.do").forward(req,resp);
            // 重定向
            //resp.sendRedirect("readFromRequest.do");
        }
    }

![6109cc103facfb6af5dd2747d73b7ba3.gif][]

![ebc40e7c9fa8b695e848474d5bc69a82.gif][]

request域中读取数据

package com.msb.testRequest;
    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;
    import java.util.List;
    /**
     * @Author: Ma HaiYang
     * @Description: MircoMessage:Mark_7001
     */
    @WebServlet(urlPatterns="/readFromRequest.do")
    public class Servlet2 extends HttpServlet {
        @Override
        protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            // 移除域中的互数据
            req.removeAttribute("gender");
            // 从request域中读取数据
            List<String> list =(List<String>) req.getAttribute("list");
            System.out.println(list);
            System.out.println(req.getAttribute("gender"));
            System.out.println(req.getAttribute("name"));
            //获取Request中的请求参数
            System.out.println(req.getParameter("username"));
            System.out.println(req.getParameter("password"));
        }
    }

![c789490a620ab8704836455fdfc0f0f6.gif][]

![17bb35f2a650e8a0e7721e1938cb9b77.gif][]

[6109cc103facfb6af5dd2747d73b7ba3.gif]: https://img-blog.csdnimg.cn/img_convert/6109cc103facfb6af5dd2747d73b7ba3.gif
[ebc40e7c9fa8b695e848474d5bc69a82.gif]: https://img-blog.csdnimg.cn/img_convert/ebc40e7c9fa8b695e848474d5bc69a82.gif
[c789490a620ab8704836455fdfc0f0f6.gif]: https://img-blog.csdnimg.cn/img_convert/c789490a620ab8704836455fdfc0f0f6.gif
[17bb35f2a650e8a0e7721e1938cb9b77.gif]: https://img-blog.csdnimg.cn/img_convert/17bb35f2a650e8a0e7721e1938cb9b77.gif