forward 和 redirect 的区别？

forward 和 redirect 的区别？

• 浏览器 url 地址显示不同

服务端通过 forward 返回，浏览器 url 地址不会发生变化；服务器通过 redirect 返回，浏览器会重新请求， url 地址会发生变化

• 前后台两者页面跳转的处理方式不同

 forward 跳转页面，是服务端进行页面跳转加载（include）新页面，直接返回到浏览器；redirect 跳转页面，是服务端返回新的 url 地址，浏览器二次发出 url 请求

• 参数携带情况不一样

forward 跳转页面，会携带请求的参数到新的页面；redirect 跳转页面，属于一次全新的 http 请求，无法携带上一次请求的参数

• http 请求次数不同

forward 1次；redirect 2次

基于 servlet 实现

test servlet

package constxiong;

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;

/**
 * test servlet
 * @author ConstXiong
 * @date 2019-06-26 10:00:34
 */
@WebServlet("/test")
public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

    public TestServlet() {
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.getWriter().write("This is test.");
	}

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

}

请求返回

redirect servlet

package constxiong;

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;

/**
 * redirect servlet
 * @author ConstXiong
 * @date 2019-06-26 10:00:34
 */
@WebServlet("/redirect")
public class RedirectServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

    public RedirectServlet() {
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.sendRedirect("http://www.baidu.com");
	}

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

}

请求返回

forward servlet

package constxiong;

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;

/**
 * forward servlet
 * @author ConstXiong
 * @date 2019-06-26 10:00:34
 */
@WebServlet("/forward")
public class ForwardServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

    public ForwardServlet() {
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.getRequestDispatcher("/test").forward(request, response);//forward 跳转到 test 请求
	}

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

}

请求返回

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