Java中如何使用Response重定向

直接来，ResponseDemo1代码，get请求到post请求，重定向到ResponseDemo2

我的虚拟目录为

ResponseDemo1代码，302是重定向状态码，Http状态码大全

package com.lingaolu.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;

/**
 * @author 林高禄
 * @create 2020-07-10-15:24
 */
@WebServlet("/responseDemo1")
public class ResponseDemo1 extends HttpServlet {
 @Override
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  System.out.println("responseDemo1进来了......");
  // 设置状态码为302
  response.setStatus(302);
  // 动态获取虚拟目录，以后修改虚拟目录的时候就不用了修改代码
  String contextPath = request.getContextPath();
  // 设置响应头location
  response.setHeader("location",contextPath+"/responseDemo2");
 }

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

ResponseDemo2代码

package com.lingaolu.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;

/**
 * @author 林高禄
 * @create 2020-07-10-15:24
 */
@WebServlet("/responseDemo2")
public class ResponseDemo2 extends HttpServlet {
 @Override
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  System.out.println("responseDemo2进来了......");
 }

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

浏览器访问，访问前

浏览器访问，访问后

控制台输出

从以上结果可以看出：

• 浏览器上的请求地址变了
• 重定向是2次请求，一次是responseDemo1请求，一次是responseDemo2请求

由于状态码固定是302，响应头固定是location，所以请求转发提供了更方便的方式

void sendRedirect(String var1)

ResponseDemo3代码

package com.lingaolu.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;

/**
 * @author 林高禄
 * @create 2020-07-10-15:24
 */
@WebServlet("/responseDemo3")
public class ResponseDemo3 extends HttpServlet {
 @Override
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  System.out.println("responseDemo3进来了......");;
  // 动态获取虚拟目录，以后修改虚拟目录的时候就不用了修改代码
  String contextPath = request.getContextPath();
  response.sendRedirect(contextPath+"/responseDemo2");

 }

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

启动，浏览器访问

控制台输出

我们把ResponseDemo3代码改一下，重定向到百度

package com.lingaolu.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;

/**
 * @author 林高禄
 * @create 2020-07-10-15:24
 */
@WebServlet("/responseDemo3")
public class ResponseDemo3 extends HttpServlet {
 @Override
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  System.out.println("responseDemo3进来了......");;
  response.sendRedirect("http://www.baidu.com");

 }

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

重启访问，就重定向到百度了

从上面结果我们可以看出，重定向可以访问其他服务器的资源

我们写一个ResponseDemo4，探索一下共享数据情况，ResponseDemo4里请求写进了一个数据name

package com.lingaolu.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;

/**
 * @author 林高禄
 * @create 2020-07-10-15:24
 */
@WebServlet("/responseDemo4")
public class ResponseDemo4 extends HttpServlet {
 @Override
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  System.out.println("responseDemo4进来了......");
  request.setAttribute("name","林大帅");
  String contextPath = request.getContextPath();
  response.sendRedirect(contextPath+"/responseDemo2");

 }

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

同时ResponseDemo2改一下，获取数据name

重启，浏览器访问

控制台输出：

从上面的null可以看出，重定向不可以共享数据

重定向的特点总结：（与之对应的------请求转发详情与特点）

• 浏览器地址栏路径发生变化，最终地址为最后转发的地址
• 转发只是多次请求，转发几次就几次请求，不共享数据
• 可以访问其他服务器的资源

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