前言

根据理论,编写demo进行验证

1. Servlet接口的简单实现类, 不使用web.xml配置,而使用servlet3.0支持的注解@WebServlet配置.
   @WebServlet("/demo1")相当于web.xml中

<!--配置Servlet--><!--在web.xml中配置：--><!--配置Servlet --><servlet><servlet-name>servletDemo1</servlet-name><servlet-class>cn.itcast.web.servlet.ServletDemo1</servlet-class></servlet><servlet-mapping><servlet-name>servletDemo1</servlet-name><url-pattern>/demo1</url-pattern></servlet-mapping>

关于 <load-on-startup>的注解等效替换待补充.

package cn.itcast.web.servlet;import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;@WebServlet("/demo1")
public class ServletDemo1 implements Servlet {@Overridepublic void init(ServletConfig servletConfig) throws ServletException {}@Overridepublic ServletConfig getServletConfig() {return null;}@Overridepublic void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {System.out.println("demo1....");}@Overridepublic String getServletInfo() {return null;}@Overridepublic void destroy() {}
}//关于GenericServlet 抽象类的简单示例,(没什么用),就一个service方法需要实现,其他空实现
class ServletDemo2 extends javax.servlet.GenericServlet {@Overridepublic void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {System.out.println("demo2.....");}
}//关于HttpServlet接口  的简单实现,(常用),有doGet doPost
/*** Servlet路径配置, 有3种*/
//@WebServlet({"/d4","/dd4","/ddd4"})
//@WebServlet("/user/demo4")
//@WebServlet("/user/*")
//@WebServlet("/*")
@WebServlet("*.do")
class ServletDemo3 extends javax.servlet.http.HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("doGet....");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("doPost...");}
}

2. 关于HttpServletRequest的常用方法, 重点关注post请求体数据流乱码解决+Enumeration类的迭代获取请求头+ServletContext 理解+URI vs URL+根据请求头内容防盗链/处理浏览器兼容问题.

package cn.itcast.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;/*** 演示Request对象获取请求行数据*/@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//演示获取请求头数据//1.获取所有请求头名称Enumeration<String> headerNames = request.getHeaderNames();//2.遍历while(headerNames.hasMoreElements()){String name = headerNames.nextElement();//根据名称获取请求头的值String value = request.getHeader(name);System.out.println(name+"---"+value);}//演示获取请求头数据:user-agentString agent = request.getHeader("user-agent");//判断agent的浏览器版本if(agent.contains("Chrome")){//谷歌System.out.println("谷歌来了...");}else if(agent.contains("Firefox")){//火狐System.out.println("火狐来了...");}//获取请求消息体--请求参数//1.获取字符流BufferedReader br = request.getReader();//2.读取数据String line = null;while((line = br.readLine()) != null){System.out.println(line);}//post 获取请求参数//根据参数名称获取参数值String username = request.getParameter("username");/* System.out.println("post");System.out.println(username);*///根据参数名称获取参数值的数组String[] hobbies = request.getParameterValues("hobby");/*for (String hobby : hobbies) {System.out.println(hobby);}*///获取所有请求的参数名称Enumeration<String> parameterNames = request.getParameterNames();/*while(parameterNames.hasMoreElements()){String name = parameterNames.nextElement();System.out.println(name);String value = request.getParameter(name);System.out.println(value);System.out.println("----------------");}*/// 获取所有参数的map集合Map<String, String[]> parameterMap = request.getParameterMap();//遍历Set<String> keyset = parameterMap.keySet();for (String name : keyset) {//获取键获取值String[] values = parameterMap.get(name);System.out.println(name);for (String value : values) {System.out.println(value);}System.out.println("-----------------");}//1.设置流的编码(主要是post请求的乱码,get请求的乱码已被tomcat8解决)request.setCharacterEncoding("utf-8");//获取请求参数usernameString username = request.getParameter("username");System.out.println(username);//测试请求转发System.out.println("demo8888被访问了。。。");//转发到demo9资源
/*RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9");requestDispatcher.forward(request,response);*///存储数据到request域中request.setAttribute("msg","hello");request.getRequestDispatcher("/requestDemo9").forward(request,response);//request.getRequestDispatcher("http://www.itcast.cn").forward(request,response);//获取数据Object msg = request.getAttribute("msg");System.out.println(msg);System.out.println("demo9999被访问了。。。");//测试获取servlet的上下文,据目前理解,上下文中至少包含"上一级访问url路径"ServletContext servletContext = request.getServletContext();System.out.println(servletContext);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {/*1. 获取请求方式 ：GET* String getMethod()2. (*)获取虚拟目录：/day14* String getContextPath()3. 获取Servlet路径: /requestDemo1* String getServletPath()4. 获取get方式请求参数：name=zhangsan* String getQueryString()5. (*)获取请求URI：/day14/demo1* String getRequestURI():		/day14/requestDemo1* StringBuffer getRequestURL()  :http://localhost/day14/requestDemo16. 获取协议及版本：HTTP/1.1* String getProtocol()7. 获取客户机的IP地址：* String getRemoteAddr()*///1. 获取请求方式 ：GETString method = request.getMethod();System.out.println(method);//2.(*)获取虚拟目录：/day14String contextPath = request.getContextPath();System.out.println(contextPath);//3. 获取Servlet路径: /demo1String servletPath = request.getServletPath();System.out.println(servletPath);//4. 获取get方式请求参数：name=zhangsanString queryString = request.getQueryString();System.out.println(queryString);//5.(*)获取请求URI：/day14/demo1String requestURI = request.getRequestURI();StringBuffer requestURL = request.getRequestURL();System.out.println(requestURI);System.out.println(requestURL);//6. 获取协议及版本：HTTP/1.1String protocol = request.getProtocol();System.out.println(protocol);//7. 获取客户机的IP地址：String remoteAddr = request.getRemoteAddr();System.out.println(remoteAddr);//演示获取请求头数据:refererString referer = request.getHeader("referer");System.out.println(referer);//http://localhost/day14/login.html//防盗链if(referer != null ){if(referer.contains("/day14")){//正常访问// System.out.println("播放电影....");response.setContentType("text/html;charset=utf-8");response.getWriter().write("播放电影....");}else{//盗链//System.out.println("想看电影吗？来优酷吧...");response.setContentType("text/html;charset=utf-8");response.getWriter().write("想看电影吗？来优酷吧...");}}}
}