10.7 Request请求转发

dispatcher 调度的意思 [dɪˈspætʃər]
Attribute 属性的意思 [ ˈætrɪbjuːt]

package com.itheima.web;
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.nio.charset.StandardCharsets;
/**
 * 请求转发
 */
@WebServlet("/req5")
public class RequestDemo5 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo5...");
        // 存储数据   存储一个键值对的数据，存储到request对象当中，然后会随着下面的forward转发到req6中
        request.setAttribute("msg","hello");  // 第一个参数写数据名，后面接数据内容
        // 请求转发： 将对应的demo5 的 request 和response对象转发过去
        // 第一个参数填：需要转发的路径（填demo6.java的虚拟路径）
        // 第二个参数填: 需要转发的对象
        request.getRequestDispatcher("/req6").forward(request,response);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

package com.itheima.web;
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;
/**
 * 请求转发
 */
@WebServlet("/req6")
public class RequestDemo6 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo6...");
        //获取数据
        Object msg = request.getAttribute("msg");  // 根据数据名得到数据类型
        System.out.println(msg);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}