Ruquest请求转发

Ruquest请求转发

请求转发(forward)：一种在服务器内部的资源跳转方式

实现方式：

req.getRequestDispatcher("资源B路径").forward(req,resp);

请求转发资源间共享数据：使用Request对象

void setAttribute(String name,Object o)：存储数据到request域中

Object getAttribute(String name)：根据key，获取值

void removeAttribute(String name)：根据key，删除该键值对

代码示例：

RequestDemo05：

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("/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
        request.setAttribute("msg","hello");

        //请求转发
        request.getRequestDispatcher("/req6").forward(request,response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

Request06：

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");
        System.out.println(msg);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

执行结果：

URL访问req5：

控制台输出请求转发的数据：

 请求转发特点：

1、浏览器地址栏不发生变化

2、只能转发到当前服务器的内部资源

3、一次请求，可以在转发的资源间使用request共享数据