JavaWeb核心编程之(三.5)HTTP请求和接受表单数据
HTTP简介
WEB浏览器与WEB拂去其之间的一问一答的交互过程, 必须遵循一定的规则,这个规则就是HTTP协议
HTTP是hypertext transfer protocol(超文本传输协议)的简写, 它是TCP/IP协议集中的一个应用层协议, 用于定义WEB浏览器与WEB服务器之间交换数据的过程以及数据本身的格式
HTTP协议的版本 HTTP/1.0 HTTP/1.1 HTTP-NG
HTTP的会话方式
四个步骤
1> 建立连接
2> 发出请求信息
3> 回送响应信息
4> 关闭连接
浏览器与WEB服务器之间的链接过程式短暂的, 每次链接只处理一个请求和响应. 对每一个页面的访问, 浏览器与WEB服务器都要建立一次单独的连接.
浏览器到WEB服务器之间的所有通讯都是完全独立分开的请求和响应对儿
创建项目testHttpForm ---> package(com.xiaoan.test) --> class(TestForm.java)
1 package com.xiaoan.test; 2 3 import java.io.IOException; 4 import java.util.Arrays; 5 import java.util.Enumeration; 6 import java.util.Map; 7 import java.util.Map.Entry; 8 9 import javax.servlet.Servlet; 10 import javax.servlet.ServletConfig; 11 import javax.servlet.ServletException; 12 import javax.servlet.ServletRequest; 13 import javax.servlet.ServletResponse; 14 import javax.servlet.http.HttpServletRequest; 15 import javax.swing.plaf.synth.SynthSeparatorUI; 16 17 public class TestForm implements Servlet{ 18 19 @Override 20 public void destroy() { 21 // TODO Auto-generated method stub 22 23 } 24 25 @Override 26 public ServletConfig getServletConfig() { 27 // TODO Auto-generated method stub 28 return null; 29 } 30 31 @Override 32 public String getServletInfo() { 33 // TODO Auto-generated method stub 34 return null; 35 } 36 37 @Override 38 public void init(ServletConfig arg0) throws ServletException { 39 // TODO Auto-generated method stub 40 41 } 42 43 @Override 44 public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException { 45 System.out.println("this is Servlet service function"); 46 //1 获取请求参数 k--v 47 String username = request.getParameter("username"); 48 String password = request.getParameter("password"); 49 System.out.println("username: " + username); 50 System.out.println("password: " + password); 51 //获取请求参数 k -- v1,v2,v3 - 表单中checkbox类型数据 52 String[] reads = request.getParameterValues("read"); 53 for(String read: reads){ 54 System.out.println("-->read: " + read); 55 } 56 57 //获取所有的参数名 58 Enumeration<String> keys = request.getParameterNames(); 59 60 //获取所有的请求参数 <k,v> 61 Map<String, String[]> params = request.getParameterMap(); 62 for(Map.Entry<String, String[]> param: params.entrySet()){ 63 System.out.println("****" + param.getKey() + ": " + Arrays.asList(param.getValue())); 64 } 65 66 /* 67 * HttpServletRequest: 是 SerlvetRequest 的子接口. 针对于 HTTP 请求所定义. 里边包含了大量获取 HTTP 请求相关的方法. 68 */ 69 70 //获取请求的URI 71 HttpServletRequest httpServletRequest = (HttpServletRequest) request; 72 String uri = httpServletRequest.getRequestURI(); 73 System.out.println("request uri: " + uri); 74 75 //获得请求方式 76 String method = httpServletRequest.getMethod(); 77 System.out.println("request method: " + method); 78 79 //如果是get请求, 则获得问号传参后面的部分, 如果是post请求该项返回null 80 String getstr = httpServletRequest.getQueryString(); 81 System.out.println("getstr: " + getstr); 82 83 //获取请求的 Serlvet 的映射路径 84 String servletPath = httpServletRequest.getServletPath(); 85 System.out.println(servletPath); 86 } 87 88 }
--> 配置web.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> 3 <display-name>testHttpForm</display-name> 4 5 6 <servlet> 7 <servlet-name>formServlet</servlet-name> 8 <servlet-class>com.xiaoan.test.TestForm</servlet-class> 9 </servlet> 10 <servlet-mapping> 11 <servlet-name>formServlet</servlet-name> 12 <url-pattern>/formServlet</url-pattern> 13 </servle
写表单(WebContent目录下) 新建testform.html
1 <!DOCTYPE html> 2 <html> 3 <head> 4 <meta charset="UTF-8"> 5 <title>Insert title here</title> 6 </head> 7 <body> 8 <form action="/testHttpForm/formServlet" method="get"> 9 username: <input type="text" name="username"><br> 10 password: <input type="password" name="password"><br> 11 多选测试:<input type="checkbox" name="read" value=1>1 12 <input type="checkbox" name="read" value=2>2 13 <input type="checkbox" name="read" value=3>3 14 <input type="checkbox" name="read" value=4>4 15 <input type="checkbox" name="read" value=5>5 16 <input type="submit" name="submit" value="提交"> 17 </form> 18 </body> 19 </html>
提交方式 get和post切换一下, 看看有什么不同
