DSP

JavaWeb基础系列（三）Request

2019-07-13 14:46发布生成海报

站内文章 / DSP

16430 0

class="markdown_views prism-kimbie-light">

一、HttpServletRequest概述

我们在创建Servlet时会覆盖service()方法，或doGet()/doPost()方法，这些方法都有两个参数，一个代表请求的request和代表响应response
service方法中的request的类型是ServletRequest，而doGet()/doPost()方法的request的类型是HttpServletRequest，HttpServletRequest是ServletRequest的子类接口，功能和方法更加强大。

二、Request的运行流程

三、通过Request获得请求信息

Http请求：

因为request代表请求，所以我们可以通过该对象分别获得Http请求的请求行，请求头和请求体。

1、通过request获得请求行

获得客户端的请求方式：String getMethod()
获得请求的资源：
String getRequestURI()
StringBuffer getRequestURL()
String getContextPath() —web应用的名称
String getQueryString() —- get提交url地址后的参数字符串username=zhangsan&password=123
注意：request获得客户机（客户端）的一些信息
request.getRemoteAddr() — 获得访问的客户端IP地址
案例演示：
login.html：


<html>
<head>
    <meta charset="UTF-8">
    <title>title>
head>
<body>
<form action="/Servlet4" method="get">
    用户名:<input type="text" name="username"/><br />
    密码：<input type="password" name="password" /><br />
    <input type="submit" value="登录" />
form>
body>
html>

Servlet4：

@WebServlet(name = "Servlet4",
        urlPatterns = {"/Servlet4"})
public class Servlet4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取请求方式
        String method = request.getMethod();
        System.out.println(method);
        //获得请求的资源
        String requestURI = request.getRequestURI();
        StringBuffer requestURL = request.getRequestURL();
        System.out.println("URI："+requestURI);
        System.out.println("URL："+requestURL);
        //获得WEB应用名称
        String contextPath = request.getContextPath();
        System.out.println("WEB应用："+contextPath);
        //地址后的参数字符串
        String queryString = request.getQueryString();
        System.out.println(queryString);
    }
}

注意：request获得客户机（客户端）的一些信息
request.getRemoteAddr() — 获得访问的客户端IP地址

2、通过request获得请求头

主要方法有：
long getDateHeader(String name)
String getHeader(String name)
Enumeration getHeaderNames()
Enumeration getHeaders(String name)
int getIntHeader(String name)

3、通过request获得请求体

请求体中的内容是通过post提交的请求参数，格式是：
username=zhangsan&password=123&hobby=football&hobby=basketball
key ———————- value
username———- [ zhangsan ]
password —————[ 123 ]
hobby ——— [ football，basketball ]
以上面参数为例，通过一下方法获得请求参数：

String getParameter(String name) 
String[] getParameterValues(String name)
Enumeration getParameterNames()
Map<String,String[]> getParameterMap()

注意：get请求方式的请求参数上述的方法一样可以获得
解决post提交方式的乱码：request.setCharacterEncoding(“UTF-8”);
解决get提交的方式的乱码：parameter = new String(parameter.getbytes(“iso8859-1”),”utf-8”);
案例演示：
login1.html：


<html>
<head>
    <meta charset="UTF-8">
    <title>title>
head>
<body>
<form action="/Servlet5" method="get">
    用户名:<input type="text" name="username"/><br />
    密码：<input type="password" name="password" /><br />
    <input type="checkbox" name="hobby" value="zq">足球
    <input type="checkbox" name="hobby" value="pq">排球
    <input type="checkbox" name="hobby" value="lq">篮球
    <input type="submit" value="提交" />
form>
body>
html>

Servlet5：

@WebServlet(name = "Servlet5",
        urlPatterns = {"/Servlet5"})
public class Servlet5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获得单个表单值
        String username = request.getParameter("username");
        System.out.println(username);
        String password = request.getParameter("password");
        System.out.println(password);
        //获得多个表单值
        String[] hobbies = request.getParameterValues("hobby");
        for(String hobby:hobbies){
            System.out.println(hobby);
        }
        System.out.println("---------");
        //获得所有的参数，参数封装到一个map中
        Map parameterMap = request.getParameterMap();
        for(Map.Entry entry:parameterMap.entrySet()){
            System.out.println(entry.getKey());
            for(String str:entry.getValue()){
                System.out.println(str);
            }
        }
    }
}

运行结果：
tom
123
zq
lq
~~~~~~~~~~~~~
username
tom
password
123
hobby
zq
lq

四、Request其他功能

4.1、request是一个域对象

request对象也是一个存储数据的区域对象，所以也具有如下方法：
setAttribute(String name, Object o)
getAttribute(String name)
removeAttribute(String name)
注意：request域的作用范围：一次请求中

4.2、request完成请求转发

获得请求转发器—-path是转发的地址
RequestDispatcher getRequestDispatcher(String path)
通过转发器对象转发
requestDispathcer.forward(ServletRequest request, ServletResponse response)
注意：ServletContext域与Request域的生命周期比较？
ServletContext：
    创建：服务器启动
    销毁：服务器关闭
    域的作用范围：整个web应用
request：
    创建：访问时创建request
    销毁：响应结束request销毁
    域的作用范围：一次请求中
注意：转发与重定向的区别？
    1）重定向两次请求，转发一次请求
    2）重定向地址栏的地址变化，转发地址不变
    3）重新定向可以访问外部网站转发只能访问内部资源
    4）转发的性能要优于重定向
注意：客户端地址与服务器端地址的写法？
客户端地址：
    是客户端去访问服务器的地址，服务器外部的地址，特点：写上web应用名称
服务器端地址：
    服务器内部资源的跳转的地址，特点：不需要写web应用的名称

@WebServlet(name = "Servlet6",
        urlPatterns = {"/Servlet6"})
public class Servlet6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //转发到Servlet3
        RequestDispatcher dispatcher = request.getRequestDispatcher("/Servlet3");
        dispatcher.forward(request,response);
    }
}

五、案例：用户注册功能

前端代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

<html>
    <head>
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>龙心商城首页title>
        <link rel="stylesheet" href="css/bootstrap.min.css" type="text/css" />
        <script src="js/jquery-1.11.3.min.js" type="text/javascript">script>
        <script src="js/bootstrap.min.js" type="text/javascript">script>
    head>

    <body>
        <div class="container-fluid">

            
            <jsp:include page="/header.jsp">jsp:include>

            
            <div class="container-fluid">
                <div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
                    
                    <ol class="carousel-indicators">
                        <li data-target="#carousel-example-generic" data-slide-to="0" class="active">li>
                        <li data-target="#carousel-example-generic" data-slide-to="1">li>
                        <li data-target="#carousel-example-generic" data-slide-to="2">li>
                    ol>
                    
                    <div class="carousel-inner" role="listbox">
                        <div class="item active">
                            <img src="img/1.jpg">
                            <div class="carousel-caption">
                                
                            div>
                        div>
                        <div class="item">
                            <img src="img/2.jpg">
                            <div class="carousel-caption">
                                
                            div>
                        div>
                        <div class="item">
                            <img src="img/3.jpg">
                            <div class="carousel-caption">
                                
                            div>
                        div>
                    div>

                    
                    <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
                        <span class="glyphicon glyphicon-chevron-left" aria-hidden="true">span>
                        <span class="sr-only">Previousspan>
                    a>
                    <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
                        <span class="glyphicon glyphicon-chevron-right" aria-hidden="true">span>
                        <span class="sr-only">Nextspan>
                    a>
                div>
            div>

            
            <div class="container-fluid">
                <div class="col-md-12">
                    <h2>热门商品  <img src="img/title2.jpg"/>h2>
                div>
                <div class="col-md-2" style="border:1px solid #E7E7E7;border-right:0;padding:0;">
                    <img src="products/hao/big01.jpg" width="205" height="404" style="display: inline-block;"/>
                div>
                <div class="col-md-10">
                    <div class="col-md-6" style="text-align:center;height:200px;padding:0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/middle01.jpg" width="516px" height="200px" style="display: inline-block;">
                        a>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small03.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small04.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2 yes-right-border" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small05.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small03.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small04.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2 yes-right-border" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small05.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>
                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small03.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small04.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small05.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>
                div>
            div>

            
            <div class="container-fluid">
                <img src="products/hao/ad.jpg" width="100%"/>
            div>

            
            <div class="container-fluid">
                <div class="col-md-12">
                    <h2>最新商品  <img src="img/title2.jpg"/>h2>
                div>
                <div class="col-md-2" style="border:1px solid #E7E7E7;border-right:0;padding:0;">
                    <img src="products/hao/big01.jpg" width="205" height="404" style="display: inline-block;"/>
                div>
                <div class="col-md-10">
                    <div class="col-md-6" style="text-align:center;height:200px;padding:0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/middle01.jpg" width="516px" height="200px" style="display: inline-block;">
                        a>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small03.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small04.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2 yes-right-border" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small05.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small03.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small04.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p><a href="product_info.html" style='color:#666'>冬瓜a>p>
                        <p><font color="#E4393C" style="font-size:16px">¥299.00font>p>
                    div>

                    <div class="col-md-2 yes-right-border" style="text-align:center;height:200px;padding:10px 0px;">
                        <a href="product_info.htm">
                            <img src="products/hao/small05.jpg" width="130" height="130" style="display: inline-block;">
                        a>
                        <p>


                         
                         
     
  
      Ta的文章  更多 >> 
             
      


                    
          JavaWeb基础系列（三）Request
               
                0 个评论
               
              
                              
          对设备的控制和远程控制方式
               
                0 个评论
               
              
                               

              
                  
  

  
  
    
         
  
      热门文章


      



  
    
      
      举报内容
    
    






检举类型


检举内容


检举用户




检举原因



广告推广


恶意灌水


回答内容与提问无关



抄袭答案


其他





检举说明(必填)






    

                
                 
      



    

  


 打开微信“扫一扫”，打开网页后点击屏幕右上角分享按钮
 

 





   


  
    
    



      
      
       
  
      




  
             
            
                    Copyright © 2024 平头弟 京ICP备15032243号-1
                         投诉举报邮箱：nettui@qq.com

JavaWeb基础系列（三）Request

一、HttpServletRequest概述

二、Request的运行流程

三、通过Request获得请求信息

1、通过request获得请求行

2、通过request获得请求头

3、通过request获得请求体

四、Request其他功能

4.1、request是一个域对象

4.2、request完成请求转发

五、案例：用户注册功能

Ta的文章 更多 >>

热门文章

举报内容

检举类型

检举原因

检举说明(必填)

打开微信“扫一扫”，打开网页后点击屏幕右上角分享按钮

Ta的文章更多 >>