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
     
       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
     
       getParameterNames():获取所有请求的参数名称    4. Map
      
        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
       
         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
        
          parameterMap = request.getParameterMap();        //遍历        Set
         
           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);    }}