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RequestResponse使用

news 2025/8/18 2:47:31

文章目录

  • 一、Request&Response介绍
  • 二、Request 继承体系
  • 三、Request 获取请求数据
    • 1、获取请求数据方法
      • （1）、请求行
      • （2）、请求头
      • （3）、请求体
    • 2、通过方式获取请求参数
    • 3、IDEA模板创建Servlet
    • 4、请求参数中文乱码处理
  • 四、Request 请求转发
  • 五、Response 设置相应数据功能介绍
  • 六、Response 完成重定向
    • 路径问题
  • 七、Response 响应字符数据
  • 八、Response 响应字节数据

一、Request&Response介绍

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二、Request 继承体系

在这里插入图片描述

三、Request 获取请求数据

1、获取请求数据方法

（1）、请求行

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   @Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// String getMethod()：获取请求方式： GETString method = req.getMethod();System.out.println(method);//GET// String getContextPath()：获取虚拟目录(项目访问路径)：/request-demoString contextPath = req.getContextPath();System.out.println(contextPath);// StringBuffer getRequestURL(): 获取URL(统一资源定位符)：http://localhost:8080/request-demo/req1StringBuffer url = req.getRequestURL();System.out.println(url.toString());// String getRequestURI()：获取URI(统一资源标识符)： /request-demo/req1String uri = req.getRequestURI();System.out.println(uri);// String getQueryString()：获取请求参数（GET方式）： username=zhangsanString queryString = req.getQueryString();System.out.println(queryString);//------------// 获取请求头：user-agent: 浏览器的版本信息String agent = req.getHeader("user-agent");System.out.println(agent);}

（2）、请求头

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// 获取请求头：user-agent: 浏览器的版本信息String agent = req.getHeader("user-agent");System.out.println(agent);

（3）、请求体

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@Overrideprotected 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);}

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><form action="/request-demo/req4" method="post"><input type="text" name="username"><input type="password" name="password"><input type="submit"></form></body>
</html>

2、通过方式获取请求参数

统一doGet和doPost方法内的代码
在这里插入图片描述

package com.itheima.web.request;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.util.Map;/*** request 通用方式获取请求参数*/
@WebServlet("/req2")
public class RequestDemo2 extends HttpServlet {@Overrideprotected 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 lisiSystem.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);}@Overrideprotected 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 lisiSystem.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);*/}
}
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><form action="/request-demo/req4" method="post"><input type="text" name="username"><br><input type="password" name="password"><br><input type="checkbox" name="hobby" value="1"> 游泳<input type="checkbox" name="hobby" value="2"> 爬山 <br><input type="submit"></form></body>
</html>

3、IDEA模板创建Servlet

在这里插入图片描述

4、请求参数中文乱码处理

在这里插入图片描述

package com.itheima.web.request;import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;public class URLDemo {public static void main(String[] args) throws UnsupportedEncodingException {String username = "张三";//1. URL编码String encode = URLEncoder.encode(username, "utf-8");System.out.println(encode);//2. URL解码//String decode = URLDecoder.decode(encode, "utf-8");String decode = URLDecoder.decode(encode, "ISO-8859-1");System.out.println(decode);//3. 转换为字节数据,编码byte[] bytes = decode.getBytes("ISO-8859-1");/*  for (byte b : bytes) {System.out.print(b + " ");}*///4. 将字节数组转为字符串，解码String s = new String(bytes, "utf-8");System.out.println(s);}
}
package com.itheima.web.request;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.nio.charset.StandardCharsets;/*** 中文乱码问题解决方案*/
@WebServlet("/req4")
public class RequestDemo4 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1. 解决乱码：POST，getReader()//request.setCharacterEncoding("UTF-8");//设置字符输入流的编码//2. 获取usernameString username = request.getParameter("username");System.out.println("解决乱码前："+username);//3. GET,获取参数的方式：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);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

在这里插入图片描述

四、Request 请求转发

在这里插入图片描述
在这里插入图片描述
demo5

package com.itheima.web.request;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("/req5")
public class RequestDemo5 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("demo5...");System.out.println(request);//存储数据request.setAttribute("msg","hello");//请求转发request.getRequestDispatcher("/req6").forward(request,response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

demo6

package com.itheima.web.request;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;/*** 请求转发*/
@WebServlet("/req6")
public class RequestDemo6 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("demo6...");System.out.println(request);//获取数据Object msg = request.getAttribute("msg");System.out.println(msg);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

五、Response 设置相应数据功能介绍

在这里插入图片描述

六、Response 完成重定向

在这里插入图片描述
在这里插入图片描述
ResponseDemo1

package com.itheima.web.response;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;@WebServlet("/resp1")
public class ResponseDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("resp1....");//重定向/*//1.设置响应状态码 302response.setStatus(302);//2. 设置响应头 Locationresponse.setHeader("Location","/request-demo/resp2");*/response.sendRedirect(contextPath+"/resp2");//response.sendRedirect("https://www.itcast.cn");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

ResponseDemo2

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 {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("resp2....");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

路径问题

在这里插入图片描述

package com.itheima.web.response;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;@WebServlet("/resp1")
public class ResponseDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("resp1....");//重定向/*//1.设置响应状态码 302response.setStatus(302);//2. 设置响应头 Locationresponse.setHeader("Location","/request-demo/resp2");*///简化方式完成重定向//动态获取虚拟目录String contextPath = request.getContextPath();response.sendRedirect(contextPath+"/resp2");//response.sendRedirect("https://www.itcast.cn");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

七、Response 响应字符数据

在这里插入图片描述
在这里插入图片描述

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 {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");//1. 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}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

八、Response 响应字节数据

在这里插入图片描述

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 {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1. 读取文件FileInputStream fis = new FileInputStream("d://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);fis.close();}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

        <dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.6</version></dependency>
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