转发（request.setRequestDispacter）和重定向（response.sendRedirect）的区别以及转发的include和forward的区别

//response 重定向的时候，url是会跳转到新的页面的，输入的地址要包含项目名（可以跳到项目之外的页面，比如百度）
//request 请求转发的时候，url是不会跳转到新页面的，输入的地址不包含项目名（只可以在此项目中进行跳转 ）

/*request.getRequestDispatcher("/RquestDemo5").forward(request, response);
*request.getRequestDispatcher("/RquestDemo5").include(request, response); 的区别
*
*在原页面out.write("11111") ,在新的页面out.write("22222");
*
*forward :在浏览器显示的是 22222
*include ：在浏览器中显示的11111
*/

这个自己写一两个小demo试一试就知道了

页面一(原页面)：

package com.chensi;

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

/**
 * Servlet  请求转发和请求重定向  进行一下 对比
 */
@WebServlet("/RequestDemo4")
public class RequestDemo4 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        
        String str = "66666";
        request.setAttribute("str", str);
        //request.getRequestDispatcher("/RequestDemo/RquestDemo5").forward(request, response);
        request.getRequestDispatcher("/RquestDemo5").forward(request, response);
        //request.getRequestDispatcher("http://WWW.baidu.com").forward(request, response);
        //response.sendRedirect("/RequestDemo/RquestDemo5");
        //response.sendRedirect("http://WWW.baidu.com");
        //request.getRequestDispatcher("/RquestDemo5").include(request, response);
        response.getWriter().write("111111111111");
    }

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

}

页面二(被跳转的页面):

package com.chensi;

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

/**
 * Servlet implementation class RquestDemo5
 */
@WebServlet("/RquestDemo5")
public class RquestDemo5 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        //System.out.println("我试试 进没进来这个demo5");
        //response.getWriter().write("这个是被转发或者重定向 的页面！！！demo5");
        //System.out.println(request.getAttribute("str"));
        response.getWriter().write("22222222");

    }

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

}