技术教程 编程教程 一篇博客上手request和response 正文

一篇博客上手request和response

2023-06-07,,

概念

request：获取请求数据

response：设置响应数据

Request

request继承体系

ServletRequest——Java提供的请求对象根接口

HttpServletRequest——Java提供的对http协议封装的请求对象接口

RequestFacade——tomcat实现定义类

request获取数据

package com.itheijma.web;

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.BufferedReader;

import java.io.IOException;

@WebServlet("/req1")

public class RequestDemo1 extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //String method() 获取请求方式

        String method = req.getMethod();

        System.out.println(method);

        //String getContextPath() 获取虚拟目录（项目访问路径）

        String contextPath = req.getContextPath();

        System.out.println(contextPath);

        //StringBuffer getRequestURL() 获取URL（统一资源定位符）

        StringBuffer url = req.getRequestURL();

        System.out.println(url.toString());

        //String getRequestURI() 获取URI（统一资源标识符）

        String uri = req.getRequestURI();

        System.out.println(uri);

        //String getQueryString() 获取请求参数（get方式）

        String queryString = req.getQueryString();

        System.out.println(queryString);

        //------------

        //获取请求头

        String agent = req.getHeader("user-agent");

        System.out.println(agent);

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //获取post请求体：请求参数

        // 1. 获取字符输入流

        BufferedReader br = req.getReader();

        // 2. 读取数据

        String line = br.readLine();

        System.out.println(line);

    }

}

request通用的方式获取数据

package com.itheijma.web;

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.Map;

@WebServlet("/req2")

public class RequestDemo2 extends HttpServlet{

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //get请求逻辑

//        System.out.println("get...");

        // 1.获取所有参数的map集合

        Map<String, String[]> map = req.getParameterMap();

        for (String key : map.keySet()) {

            //username:zhangsan

            System.out.print(key+":");

            //获取值

            String[] values = map.get(key);

            for (String value : values) {

                System.out.print(value + " ");

            }

            System.out.println();

        }

        System.out.println("----------");

        // 2.根据key获取参数值，数组

        String[] hobbies = req.getParameterValues("hobby");

        for (String hobby : hobbies) {

            System.out.println(hobby);

        }

        // 3. 根据key获取单个参数值

        String username = req.getParameter("username");

        String password = req.getParameter("password");

        System.out.println(username);

        System.out.println(password);

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //post请求逻辑

        this.doGet(req,resp);

//        System.out.println("post...");

//        // 1.获取所有参数的map集合

//        Map<String, String[]> map = req.getParameterMap();

//        for (String key : map.keySet()) {

//            //username:zhangsan

//            System.out.print(key+":");

//

//            //获取值

//            String[] values = map.get(key);

//            for (String value : values) {

//                System.out.print(value + " ");

//            }

//

//            System.out.println();

//        }

//

//        System.out.println("----------");

//

//        // 2.根据key获取参数值，数组

//        String[] hobbies = req.getParameterValues("hobby");

//        for (String hobby : hobbies) {

//

//            System.out.println(hobby);

//        }

//

//        // 3. 根据key获取单个参数值

//        String username = req.getParameter("username");

//        String password = req.getParameter("password");

//        System.out.println(username);

//        System.out.println(password);

    }

}

request请求参数中文乱码解决方法

package com.itheijma.web;

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.nio.charset.StandardCharsets;

/**

 * 中文乱码问题解决方案

 */

@WebServlet("/req3")

public class RequestDemo3 extends HttpServlet {

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

        this.doGet(request, response);

    }

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

        // 1. 解决乱码 POST 获取参数方式:getReader()读取数据流

        request.setCharacterEncoding("utf-8"); //设置字符输入流的编码

        // 2. 获取username

        String username = request.getParameter("username");

        System.out.println("解决乱码前："+username);

        // 3. 解决乱码 GET 获取参数方式:getQueryString

        // 乱码原因：tomcat进行url解码，默认的字符集ISO-8859-1

//        // 3.1 先对乱码数据进行编码：转为字节数组

//        byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);

//        // 3.2 字节数组解码

//        username = new String(bytes, StandardCharsets.UTF_8);

        username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);

        System.out.println("解决乱码后"+username);

    }

}

request请求转发

请求转发（forward）：一种在服务器内部的资源跳转方式。

请求转发特点：

    浏览器地址栏路径不发生变化
    只能转发到当前服务器的内部资源
    一次请求，可以在转发的资源间使用request共享数据

    req4

package com.itheijma.web;

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.nio.charset.StandardCharsets;

/**

 * 请求转发

 */

@WebServlet("/req4")

public class RequestDemo4 extends HttpServlet {

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

        this.doGet(request, response);

    }

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

        System.out.println("demo4");

        //存储数据

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

        //请求转发

        request.getRequestDispatcher("/req5").forward(request,response);

    }

}

req5

package com.itheijma.web;

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("/req5")

public class RequestDemo5 extends HttpServlet {

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

        this.doGet(request, response);

    }

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

        System.out.println("demo5");

        //获取数据

        Object msg = request.getAttribute("msg");

        System.out.println(msg);

    }

}

response

Response完成重定向

重定向：一种资源跳转的方式

resp1

package com.itheima.web.response;

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("/resp1")

public class ResponseDemo1 extends HttpServlet {

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

        this.doGet(request, response);

    }

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

        System.out.println("resp1...");

//        // 重定向

//        // 1. 设置状态码 302

//        response.setStatus(302);

//        // 2. 设置响应头 Location

//        response.setHeader("Location","/tomcat-demo2/resp2");

        // 简化方式完成重定向

        response.sendRedirect("/tomcat-demo2/resp2");

    }

}

resp2

package com.itheima.web.response;

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("/resp2")

public class ResponseDemo2 extends HttpServlet {

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

        this.doGet(request, response);

    }

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

        System.out.println("resp2...");

    }

}

重定向特点：

    浏览器地址栏路径发生变化
    可以重定向到任意位置的资源（服务器内、外部均可）
    两次请求，不能在多个资源使用request共享数据

资源路径问题（什么时候加虚拟目录）

浏览器使用：需要加虚拟目录

服务端使用：不需要加虚拟目录

动态获取虚拟目录

        //动态获取虚拟目录

        String contextPath = request.getContextPath();

        response.sendRedirect(contextPath + "/resp2");

Response响应字符数据

package com.itheima.web.response;

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.io.PrintWriter;

/**

 * 响应字符数据：设置字符数据的响应体

 */

@WebServlet("/resp3")

public class ResponseDemo3 extends HttpServlet {

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

        this.doGet(request, response);

    }

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

        response.setContentType("text/html;charset=utf-8");

        //获取字符输出流

        PrintWriter writer = response.getWriter();

        //content-type

        //response.setHeader("content-type","text/html");

        writer.write("你好");

        writer.write("<h1>aaa</h1>");

        //细节：流不需要关闭

    }

}

Response响应字节数据

package com.itheima.web.response;

import org.apache.commons.io.IOUtils;

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.FileInputStream;

import java.io.IOException;

import java.io.PrintWriter;

/**

 * 响应字节数据：设置字节数据的响应体

 */

@WebServlet("/resp4")

public class ResponseDemo4 extends HttpServlet {

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

        this.doGet(request, response);

    }

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

        // 1. 读取文件

        FileInputStream fis = new FileInputStream("e://a.jpg");

        // 2. 获取response字节输出流

        ServletOutputStream os = response.getOutputStream();

        // 3. 完成流的copy

//        byte[] buff = new byte[1024];

//        int len = 0;

//        while ((len = fis.read(buff)) != -1){

//            os.write(buff,0,len);

//        }

        IOUtils.copy(fis,os);//使用工具类

        fis.close();

    }

}

pom文件导入工具类

<dependency>

            <groupId>commons-io</groupId>

            <artifactId>commons-io</artifactId>

            <version>2.6</version>

        </dependency>

一篇博客上手request和response的相关教程结束。

《一篇博客上手request和response.doc》

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