• 请求和响应

    目录

    1 请求对象

    1.1 请求对象介绍

    • 请求：获取资源。在 BS 架构中，就是客户端浏览器想服务器端发出询问
    • 请求对象：就是在项目中用于发送请求的对象

    1.2 请求对象常用方法-获取各自路径

    在这里插入图片描述

    • 代码演示
    package com.txt.servlet;

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;
@WebServlet("/servletDemo01")
public class ServletDemo01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取虚拟目录名称
        String contextPath = req.getContextPath();
        System.out.println(contextPath);

        //2.获取Servlet映射路径
        String servletPath = req.getServletPath();
        System.out.println(servletPath);

        //3.获取访问者ip
        String ip = req.getRemoteAddr();
        System.out.println(ip);

        //4.获取请求消息数据
        String queryString = req.getQueryString();
        System.out.println(queryString);

        //5.获取统一资源标识符
        String requestURI = req.getRequestURI();
        System.out.println(requestURI);

        //6.获取统一资源定位符
        StringBuffer requestURL = req.getRequestURL();
        System.out.println(requestURL);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    • 演示效果：
      在这里插入图片描述

    1.3 请求对象常用方法-获取请求头信息

    在这里插入图片描述

    • 代码演示：
    package com.txt.servlet;

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.util.Enumeration;

@WebServlet("/servletDemo02")
public class ServletDemo02 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //根据请求头名称获取一个值
        String connection = req.getHeader("connection");
        System.out.println(connection);
        System.out.println("-----------------------");

        //根据请求头的名称获取多个值
        Enumeration<String> headers = req.getHeaders("accept-encoding");
        while(headers.hasMoreElements()){
            String header = headers.nextElement();
            System.out.println(header);
        }
        System.out.println("-----------------------");

        //获取所有的请求头名称
        Enumeration<String> names = req.getHeaderNames();
        while (names.hasMoreElements()){
            String name = names.nextElement();
            String value = req.getHeader(name);
            System.out.println(name + "：" +value);
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    • 效果如下：
      在这里插入图片描述

    1.4 请求对象常用方法-请求参数信息

    在这里插入图片描述

    • 代码演示
    package com.txt.servlet;

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.util.Enumeration;
import java.util.Map;

@WebServlet("/servletDemo03")
public class ServletDemo03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1. 根据名称获取数据
        String username = req.getParameter("username");
        System.out.println(username);
        String pwd = req.getParameter("pwd");
        System.out.println(pwd);
        System.out.println("---------------------------------");

        //2.根据名称获取所有数据
        String[] hobbies = req.getParameterValues("hobby");
        for (String hobby : hobbies){
            System.out.println(hobby);
        }
        System.out.println("---------------------------------");

        //3.获取所有名称
        Enumeration<String> names = req.getParameterNames();
        while(names.hasMoreElements()){
            String name = names.nextElement();
            System.out.println(name);
        }
        System.out.println("---------------------------------");

        //获取所有参数的键值对
        Map<String, String[]> map = req.getParameterMap();
        for (String key : map.keySet()){
            String[] values = map.get(key);
            System.out.print(key + "：");
            for (String value : values){
                System.out.print(value + " ");
            }
            System.out.println();
        }

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    • 效果如下
      在这里插入图片描述

    1.5 获取请求参数并封装对象

    1. 手动封装方式
    2. 反射封装方式
    3. 工具类封装方式

    1.5.1 手动封装方式

    • 代码演示
    package com.txt.servlet;

import com.txt.bean.Student;

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.util.Enumeration;
import java.util.Map;

@WebServlet("/servletDemo04")
public class ServletDemo04 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取所有的数据
        String username = req.getParameter("username");
        String pwd = req.getParameter("pwd");
        String[] hobbies = req.getParameterValues("hobby");

        //2.封装学生对象
        Student stu = new Student(username,pwd,hobbies);

        //输出对象
        System.out.println(stu);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

//学生类
package com.txt.bean;

import java.util.Arrays;

public class Student {
    private String username;
    private String pwd;
    private String[] hobby;

    public Student() {
    }

    public Student(String username, String pwd, String[] hobby) {
        this.username = username;
        this.pwd = pwd;
        this.hobby = hobby;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public String[] getHobby() {
        return hobby;
    }

    public void setHobby(String[] hobby) {
        this.hobby = hobby;
    }

    @Override
    public String toString() {
        return "Student{" +
                "username='" + username + '\'' +
                ", pwd='" + pwd + '\'' +
                ", hobby=" + Arrays.toString(hobby) +
                '}';
    }
}


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    • 效果如下：
      在这里插入图片描述

    1.5.2 反射封装方式

    • 代码演示
    package com.txt.servlet;

import com.txt.bean.Student;

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.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Map;

//反射封装方式
@WebServlet("/servletDemo05")
public class ServletDemo05 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取所有的数据
        Map<String, String[]> map = req.getParameterMap();

        //2.封装学生对象
        Student stu = new Student();
        //2.1 遍历集合
        for (String name : map.keySet()){
            String[] value = map.get(name);
            //2.2 获取 Student对象的属性描述器
            try {
                PropertyDescriptor pd = new PropertyDescriptor(name,stu.getClass());
                //2.3 获取对应的setXxx方法
                Method writeMethod = pd.getWriteMethod();
                //执行方法
                if (value.length > 1){
                    writeMethod.invoke(stu,(Object) value);
                }else {
                    writeMethod.invoke(stu,value);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        //输出对象
        System.out.println(stu);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}



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    1.5.3 工具类封装方式

    我们需要引入jar包
    在这里插入图片描述

    • 代码演示
    package com.txt.servlet;

import com.txt.bean.Student;
import org.apache.commons.beanutils.BeanUtils;

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.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;

//工具类封装方式
@WebServlet("/servletDemo06")
public class ServletDemo06 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取所有的数据
        Map<String, String[]> map = req.getParameterMap();

        //2.封装学生对象
        Student stu = new Student();
        try {
            BeanUtils.populate(stu,map);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }

        //输出对象
        System.out.println(stu);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    1.6 流对象获取请求信息

    在这里插入图片描述

    • 代码演示
    package com.txt.servlet;

import com.txt.bean.Student;
import org.apache.commons.beanutils.BeanUtils;

import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Map;


@WebServlet("/servletDemo07")
public class ServletDemo07 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //字符流（必须是post方式）
        /*BufferedReader br = req.getReader();
        String line;
        while ((line = br.readLine()) != null){
            System.out.println(line);
        }*/

        //字节流
        ServletInputStream is = req.getInputStream();
        byte[] arr = new byte[1024];
        int len;
        while ((len = is.read(arr)) != -1){
            System.out.println(new String(arr,0,len));
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    • 效果如下
      在这里插入图片描述

    1.7 中文乱码问题

    • GET 方式
      没有乱码问题，在 Tomcat 8 版本后已经解决
    • POST 方式
      有乱码问题。可以通过 setCharacterEncoding() 方法来解决
      • 代码演示
    package com.txt.servlet;

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

@WebServlet("/servletDemo08")
public class ServletDemo08 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");

        String username = req.getParameter("username");
        System.out.println(username);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    1.8 请求域

    • 请求域（request 域）：可以再一次请求范围内进行共享数据
    • 一般用于请求转发的多个资源中共享数据
    • 请求对象操作共享数据方法
      在这里插入图片描述

    1.9 请求转发

    • 请求转发：客户端的一次请求到达后，发现需要借助其他 Servlet 来实现功能
    • 特点
      • 浏览器地址栏不变
      • 域对象中的数据不丢失
      • 负责转发的 Servlet 转发前后的响应正文会丢失
      • 由转发的目的地来响应客户端
        在这里插入图片描述
    • 代码演示
      servletDemo09：
    package com.txt.servlet;

import javax.servlet.RequestDispatcher;
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;

//工具类封装方式
@WebServlet("/servletDemo09")
public class ServletDemo09 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置共享数据
        req.setAttribute("encoding","gbk");

        //获取请求调度对象
        RequestDispatcher rd = req.getRequestDispatcher("/servletDemo10");

        //实现转发功能
        rd.forward(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    servletDemo10：

    package com.txt.servlet;

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;

//工具类封装方式
@WebServlet("/servletDemo10")
public class ServletDemo10 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取共享数据
        Object encoding = req.getAttribute("encoding");
        System.out.println(encoding);

        System.out.println("servletDemo10 执行了...");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    1.10 请求包含

    • 请求包含：可以合并其他 Servlet 中的功能一起响应给客户端
    • 特点：
      • 浏览器地址栏不变
      • 域对象中的数据不会丢失
      • 被包含的 Servlet 的响应头会丢失
        在这里插入图片描述

    2 响应对象

    2.1 响应对象介绍

    • 响应：回馈结果。在 BS 架构中，就是服务器给客户端浏览器反馈结果。
    • 响应对象：就是在项目中用于发送响应的对象

    2.2 常见状态码

    在这里插入图片描述

    2.3 字节流响应消息

    在这里插入图片描述

    • 代码演示
    package com.txt.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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;

@WebServlet("/servletDemo01")
public class ServletDemo01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //解决乱码问题
        resp.setContentType("text/html;charset=UTF-8");

        //获取字节流输出对象
        ServletOutputStream os = resp.getOutputStream();

        //定义一个消息
        String str = "你好";

        //通过字节流对象输出
        os.write(str.getBytes(StandardCharsets.UTF_8));
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    2.4 字符流响应消息

    在这里插入图片描述

    • 代码演示
    package com.txt.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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.io.PrintWriter;
import java.nio.charset.StandardCharsets;
//字符流响应消息
@WebServlet("/servletDemo02")
public class ServletDemo02 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //解决乱码问题
        resp.setContentType("text/html;charset=UTF-8");

        //获取字符输出流对象
        PrintWriter pw = resp.getWriter();

        //准备一个消息
        String str = "你好";

        //通过字符输出流输出
        pw.write(str);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    2.5 响应图片

    1. 创建字节输入流对象，关联读取的图片路径
    2. 通过响应对象获取字节输出流对象
    3. 循环读取和写出图片
    package com.txt.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;

//响应图片
@WebServlet("/servletDemo03")
public class ServletDemo03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //通过文件相对路径获取绝对路径
        String realPath = getServletContext().getRealPath("/img/qiu.jpg");

//        1. 创建字节输入流对象，关联读取的图片路径
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(realPath));

//        2. 通过响应对象获取字节输出流对象
        ServletOutputStream os = resp.getOutputStream();

//        3. 循环读取和写出图片
        byte[] bys = new byte[1024];
        int len;
        while ((len = bis.read(bys)) != -1){
            os.write(bys,0,len);
        }

        //释放资源
        bis.close();

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    2.6 设置缓存

    • 缓存：对于不经常变化的数据，我们可以设置合理缓存时间，以避免浏览器频繁请求服务器，以此来提高效率！
    • 在这里插入图片描述
    • 代码演示
    package com.txt.servlet;

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

//设置缓存
@WebServlet("/servletDemo04")
public class ServletDemo04 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       String news = "这是一条很火爆的新闻";

       //设置缓存 1小时的缓存时间
        resp.setDateHeader("Expires",System.currentTimeMillis() + 60 * 60 * 1000);


       //设置编码
        resp.setContentType("text/html;charset=UTF-8");

        //写出数据
        resp.getWriter().write(news);

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

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    2.7 定时刷新

    • 定时刷新：过了指定时间后，页面自动进行跳转
      在这里插入图片描述
    • 代码演示
    package com.txt.servlet;

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;

//定时刷新
@WebServlet("/servletDemo05")
public class ServletDemo05 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String str = "您的用户名和密码有误，3秒后自动跳转到登录页面";

       //设置编码格式
        resp.setContentType("text/html;charset=UTF-8");
        //写数据
        resp.getWriter().write(str);

        resp.setHeader("Refresh","3;URL=/response/login.html");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    2.8 请求重定向

    • 请求重定向：客户端的一次请求到达后，发现需要借助其他 Servlet 来实现功能
    • 特点：浏览器地址栏会发生改变，两次请求、请求域对象中不能共享数据，可以重定向到其他服务器
    • 响应对象重定向方法
      在这里插入图片描述
    • 代码演示
      ServletDemo06
    package com.txt.servlet;

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;

//请求重定向
@WebServlet("/servletDemo06")
public class ServletDemo06 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("servletDemo06 执行了...");

        //设置共享数据
        req.setAttribute("username","zhangsan");

        //请求重定向
        resp.sendRedirect(req.getContextPath() + "/servletDemo07");

//        resp.sendRedirect("https://www.baidu.com");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    ServletDemo07

    package com.txt.servlet;

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;

//请求重定向
@WebServlet("/servletDemo07")
public class ServletDemo07 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("servletDemo07 执行了...");

        //获取共享数据
        Object username = req.getAttribute("username");
        System.out.println(username);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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    • 运行效果
      在这里插入图片描述

    2.9 文件下载

    1. 创建字节输入流，关联读取文件
    2. 设置响应消息头支持的类型
    3. 设置响应消息头以下载方式打开资源
    4. 通过响应对象获取字节输出流对象
    5. 循环读写
    6. 释放资源
    • 代码演示
    package com.txt.servlet;

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

//文件下载
@WebServlet("/servletDemo08")
public class ServletDemo08 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        1. 创建字节输入流，关联读取文件
        String realPath = getServletContext().getRealPath("/img/qiu.jpg");
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(realPath));

//        2. 设置响应消息头支持的类型
        resp.setHeader("Content-Type","application/octet-stream");

//        3. 设置响应消息头以下载方式打开资源
        resp.setHeader("Content-Disposition","attachment;filename=qiu.jpg");

//        4. 通过响应对象获取字节输出流对象
        ServletOutputStream os = resp.getOutputStream();
//        5. 循环读写
        byte[] bys = new byte[1024];
        int len;
        while ((len = bis.read(bys)) != -1){
            os.write(bys,0,len);
        }
//        6. 释放资源
        bis.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}


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  • 原文地址：https://blog.csdn.net/m0_59620032/article/details/128091770