Request对象

电玩女神 2024-04-18 14:35 60阅读 0赞

### 文章目录 ###

*  体系结构
 *  request功能
 *   *  获取请求行数据
     *  获取请求头
     *  获取请求体
     *  获取请求参数\[通用\]
     *  请求转发：一种在服务器内部的资源跳转方式
     *  共享数据
     *  获取ServletContext

# 体系结构 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70]

# request功能 #

## 获取请求行数据 ##

package cn.oceanstar.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;
    /*
    * Response获取请求行
    * 浏览器访问：http://localhost:8080/webServlet_war_exploded/ServletDemo?name=oceanstart&age=18
    * */
    @WebServlet("/ServletDemo")
    public class ServletDemo extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
    
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            //1、获取请求方法
            String method = request.getMethod();
            System.out.println("获取请求方法：" + method); // GET
    
            //2、获取虚拟目录
            System.out.println("获取虚拟目录：" + request.getContextPath());  //获取虚拟目录：/webServlet_war_exploded
    
            //3、获取Servlet路径：
            System.out.println("获取Servlet路径：" + request.getServletPath()); // 获取Servlet路径：/ServletDemo
    
            //4、获取get方法请求参数：
            System.out.println("获取get方法请求参数：" + request.getQueryString()); //获取get方法请求参数：name=oceanstart&age=18
    
            //5、获取请求URI
            System.out.println("获取请求URI：" + request.getRequestURI()); // 获取请求URI：/webServlet_war_exploded/ServletDemo
            System.out.println("获取请求URL：" + request.getRequestURL()); //获取请求URL：http://localhost:8080/webServlet_war_exploded/ServletDemo
    
            //6、获取协议以及版本
            System.out.println("获取协议以及版本：" + request.getProtocol()); //获取协议以及版本：HTTP/1.1
    
            //7、获取客户端的IP地址
            System.out.println("获取客户端的IP地址：" + request.getRemoteAddr()); //  0:0:0:0:0:0:0:1
        }
    }

## 获取请求头 ##

package cn.oceanstar.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.util.Enumeration;
    
    @WebServlet("/ServletDemo3")
    public class ServletDemo3 extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
    
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            Enumeration<String> headNames = request.getHeaderNames();
    
            while (headNames.hasMoreElements()){
        
                String name = headNames.nextElement();
                // 根据名称获取请求头的值
                String value = request.getHeader(name);
                System.out.println(name + ":" + value);
            }
    //        host:localhost:8080
    //        connection:keep-alive
    //        upgrade-insecure-requests:1
    //        user-agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36
    //        sec-fetch-mode:navigate
    //        accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
    //        sec-fetch-site:none
    //        accept-encoding:gzip, deflate, br
    //        accept-language:zh-CN,zh;q=0.9
    //        cookie:JSESSIONID=BF91E27B988F92A23D2B1614EEBC64B1; _ga=GA1.1.1981025662.1555230476
    
    
    
    
            // 演示获取---浏览器版本
            String agent = request.getHeader("user-agent");
            if(agent.contains("Chrome")){
        
                System.out.println("谷歌");
            }else if(agent.contains("Firefox")){
        
                System.out.println("火狐");
            }
    
    
            // 获取referer:来自哪个链接
            String referer = request.getHeader("referer");
            System.out.println(referer);
    
        }
    }

## 获取请求体 ##

*  请求体：只有post请求方式，才有请求体，在请求体中封装了Post请求的请求参数

步骤：

1、获取流对象

*  BufferedReader getReader()：获取字符输入流，只能操作字符数据
 *  ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数据

2、再从流对象中拿数据

试验：

1、项目目录如下：

![在这里插入图片描述][20190908095928408.png]  
register.html内容：

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>注册页面</title>
    </head>
    <body>
    
        <form action="http://localhost:8080/Response_war_exploded/ServletDemo" method="post">
            <input type="text" placeholder="请输入用户名" name="username"><br>
            <input type="text" placeholder="请输入密码" name="password"><br>
            <input type="submit" value="注册">
        </form>
    </body>
    </html>

ServletDemo内容如下:

tomcat配置如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 1]  
2、启动项目，浏览器访问：http://localhost:8080/Response\_war\_exploded/register.html  
![在这里插入图片描述][20190908100105399.png]  
结果：控制台输出：username=admin&password=123456

## 获取请求参数\[通用\] ##

1、String getParameter(String name)：根据参数名称获取参数值  
username=admin&password=123

2、String\[\] getParameterValues(String name)：根据参数名称获取参数值的数组 hobby=xx&hobbby=yy

3、EnumerationgetParameter()：获取所有请求的参数名称  
4、Ma<String, String\[\]>getParameterMap()：获取所有参数的map集合

5、get和post请求获取参数一样  
6、解决参数中文乱码的问题

*  get：tomcat8已经将get方式乱码问题解决了
 *  post方式：会乱码  
    解决：获取参数前，设置request的编码

试验：  
项目目录如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 2]

*  register.html内容

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>注册页面</title>
    </head>
    <body>
    
        <form action="http://localhost:8080/Response_war_exploded/ServletDemo" method="post">
            <input type="text" placeholder="请输入用户名" name="username"><br>
            <input type="text" placeholder="请输入密码" name="password"><br>
    
            <input type="checkbox" name="hobby" value="game">游戏
            <input type="checkbox" name="hobby" value="study">学习
            <input type="submit" value="注册">
        </form>
    </body>
    </html>

ServletDemo内容如下:

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;
    import java.util.Enumeration;
    import java.util.Map;
    import java.util.Set;
    
    @WebServlet("/ServletDemo")
    public class ServletDemo extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            
            request.setCharacterEncoding("utf-8");
    
            
            
            //获取请求消息体----请求参数
            String username = request.getParameter("username");
            System.out.println("username:" + username);
    
            System.out.println("---------------------------------");
    
            String []hobby = request.getParameterValues("hobby");
            System.out.println("hobby:" + hobby);
            System.out.println("---------------------------------");
    
            Enumeration<String> parameterNames = request.getParameterNames();
            while (parameterNames.hasMoreElements()){
        
                String name = parameterNames.nextElement();
                String values = request.getParameter(name);
                System.out.println(name + ":" + values);
            }
    
            System.out.println("---------------------------------");
    
    
            Map<String, String[]> parameterMap = request.getParameterMap();
            Set<String> keyset = parameterMap.keySet();
            for (String name : keyset){
        
                String[] values = parameterMap.get(name);
                System.out.println(name + ":" + values);
            }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            this.doPost(request, response);
        }
    }

tomcat配置如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 3]  
2、启动项目，浏览器访问：http://localhost:8080/Response\_war\_exploded/register.html

![在这里插入图片描述][20190908100405677.png]

## 请求转发：一种在服务器内部的资源跳转方式 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 4]

步骤：

*  1、通过request对象获取请求转发器对象：RequestDispatcher getRequestDispatcher(String var1)
 *  2、使用对象来来进行转发：void forward(ServletRequest var1, ServletResponse var2) throws ServletException, IOException
 *  3、特点：
    
     *  浏览器地址路径不发生变化
     *  只能转发到当前服务器内部资源中
     *  转发是一次请求

4、转发对象在同一个tomcat下部署

5、 实践

*  1、项目目录  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 5]
 *  2、ServletDemo1内容

*  3、ServletDemo1内容

2、浏览器访问：http://localhost:8080/Response\_war\_exploded/ServletDemo1  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 6]

## 共享数据 ##

*  域对象：一个有作用范围的对象，可以在范围内共享数据
 *  request域：代表一次请求的范围，一般用于请求转发的多个资源中共享数据
 *  方法：setAttribute(String name, Object obj)：存储数据  
    getAttribute(String name)：获取数据  
    removeAttribute(String name)：移除  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 7]  
    实践：在请求转发的基础上修改
    
     *  ServletDemo1内容

*  ServletDemo2内容

## 获取ServletContext ##

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[20190908095928408.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/aef2df3ae8244006be19f746ee57bc1c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/b039ae0e40b84131864cfe2a03c308de.png
[20190908100105399.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/4d634dc1e4ec4576ac5ec89a0fe27010.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 2]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/57a44e49767841aea3186348528a9971.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 3]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/f82db52d845d4ee5bc1d7ab00ccdfc5a.png
[20190908100405677.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/1ed30d523da3422c822862b316491e04.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 5]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/8ad88f63df604be8b2fb6a4abe485735.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 6]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/e726a844bf6f4ba381e94c4ae97d4931.png
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