一、Request原理和继承体系
1. request对象和response对象的原理 1. request和response对象是由服务器创建的。我们来使用它们 2. request对象是来获取请求消息，response对象是来设置响应消息 2. request对象继承体系结构： ServletRequest -- 接口 | 继承 HttpServletRequest -- 接口 | 实现 org.apache.catalina.connector.RequestFacade 类(tomcat)
二、Request功能
1、获取请求行数据
1. 获取请求消息数据 1. 获取请求行数据 * GET /day14/demo1?name=zhangsan HTTP/1.1 * 方法： 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: /demo1 * 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/demo1 * StringBuffer getRequestURL() :http://localhost/day14/demo1 * URL:统一资源定位符 ： http://localhost/day14/demo1 中华人民共和国 * URI：统一资源标识符 : /day14/demo1 共和国 6. 获取协议及版本：HTTP/1.1 * String getProtocol() 7. 获取客户机的IP地址： * String getRemoteAddr() --------------------------------- package cn.itcast.web.request; import com.sun.scenario.effect.impl.sw.sse.SSEBlend_SRC_OUTPeer; 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("/requestDemo1") public class RequestDemo1 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //获取请求方式 String method = request.getMethod(); System.out.println(method); //获取虚拟目录 String contextPath = request.getContextPath(); System.out.println(contextPath); //获取Servlet路径 String servletPath = request.getServletPath(); System.out.println(servletPath); //获取get方式请求参数 String queryString = request.getQueryString(); System.out.println(queryString); //获取请求URI String requestURI = request.getRequestURI(); System.out.println(requestURI); StringBuffer requestURL = request.getRequestURL(); System.out.println(requestURL); //获取协议及版本 String protocol = request.getProtocol(); System.out.println(protocol); //获取客户机的IP地址 String remoteAddr = request.getRemoteAddr(); System.out.println(remoteAddr); } }
2、获取请求头数据
* 方法： * (*)String getHeader(String name):通过请求头的名称获取请求头的值 * Enumeration<String> getHeaderNames():获取所有的请求头名称 ---------------------------------- @WebServlet("/requestDemo2") public class RequestDemo2 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //演示获取请求头数据：user-agent String 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..."); } else if(agent.contains("Firefox")) { System.out.println("火狐..."); } } } ---------------------------------- @WebServlet("/requestDemo4") public class RequestDemo4 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //演示获取请求头数据：referer String referer = request.getHeader("referer"); System.out.println(referer); //防盗链 if(referer != null) { if(referer.contains("/day14")) { System.out.println("正常的"); }else { System.out.println("盗链"); } } } }
3、获取请求体数据
* 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 * 在文件上传知识点后讲解 2. 再从流对象中拿数据 ----------------------------------- @WebServlet("/requestDemo5") public class RequestDemo5 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //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); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } }
4、获取请求参数
1. 获取请求参数通用方式：不论get还是post请求方式都可以使用下列方法来获取请求参数 1. String getParameter(String name):根据参数名称获取参数值 username=zs&password=123 2. String[] getParameterValues(String name):根据参数名称获取参数值的数组 hobby=xx&hobby=game 3. Enumeration<String> getParameterNames():获取所有请求的参数名称 4. Map<String,String[]> getParameterMap():获取所有参数的map集合 -------------------------------- 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.BufferedReader; import java.io.IOException; import java.util.Enumeration; import java.util.Map; import java.util.Set; @WebServlet("/requestDemo6") public class RequestDemo6 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //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) { String[] values = parameterMap.get(name); System.out.println(name); for(String value: values) { System.out.println(value); } System.out.println("-------------"); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //get 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); this.doPost(request,response); } }
5、中文乱码问题
* get方式：tomcat 8 已经将get方式乱码问题解决了 * post方式：会乱码 * 解决：在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");
6、请求转发
请求转发：一种在服务器内部的资源跳转方式 1. 步骤： 1. 通过request对象获取请求转发器对象：RequestDispatcher getRequestDispatcher(String path) 2. 使用RequestDispatcher对象来进行转发：forward(ServletRequest request, ServletResponse response) 2. 特点： 1. 浏览器地址栏路径不发生变化 2. 只能转发到当前服务器内部资源中。 3. 转发是一次请求 3. 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： 1. void setAttribute(String name,Object obj):存储数据 2. Object getAttitude(String name):通过键获取值 3. void removeAttribute(String name):通过键移除键值对 4. 获取ServletContext： * ServletContext getServletContext() ------------------------------------ @WebServlet("/requestDemo8") public class RequestDemo8 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 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); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } } @WebServlet("/requestDemo9") public class RequestDemo9 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //获取数据 Object msg = request.getAttribute("msg"); System.out.println(msg); System.out.println("demo9999被访问了。。。"); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } } --------------------------- 获取ServletContext @WebServlet("/requestDemo10") public class RequestDemo10 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ServletContext servletContext = request.getServletContext(); System.out.println(servletContext); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }