Request 的学习

Posted yanzhudl

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  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)

     


     

  3. request功能
    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(这是一个例子)
    * 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 :/day1/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()


    【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


    【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
                        2. 再从流对象中拿数据




  4. 其他功能

    【1.获取其他请求参数(通用方式)也就是兼容GET和POST方法
    1. String getParameter(String name):根据参数名称获取参数值
    2. String[] getParameterValues(String name):根据参数名称获取参数值的数组
    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
    5.this.doPost(request,response);【在dopost中写代码,doget用此方法调用】

    * 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");


    【2.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)【资源路径/访问路径/也就是转发的地方】
                        2. 使用RequestDispatcher对象来进行转发:forward(ServletRequest request, ServletResponse response)
                            一般使用一行(写在doGet或doPost)【request.getRequestDispatcher("~~~~").forward(request,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()



  5. 实操
    步骤:启动IDEA==》new Servlet==》修改注解配置==》在方法下编写
    获取请求行数据

    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 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/requestDemo1 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() */ //1. 获取请求方式 :GET String method = request.getMethod(); System.out.println(method); //2.(*)获取虚拟目录:/day14 String contextPath = request.getContextPath(); System.out.println(contextPath); //3. 获取Servlet路径: /demo1 String servletPath = request.getServletPath(); System.out.println(servletPath); //4. 获取get方式请求参数:name=zhangsan String queryString = request.getQueryString(); System.out.println(queryString); //5.(*)获取请求URI:/day14/demo1 String requestURI = request.getRequestURI(); StringBuffer requestURL = request.getRequestURL(); System.out.println(requestURI); System.out.println(requestURL); //6. 获取协议及版本:HTTP/1.1 String 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);
    获取请求头数据

    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; import java.util.Enumeration; @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 //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);
    
    
    获取请求头数据2
    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; import java.util.Enumeration; @WebServlet("/requestDemo3") public class RequestDemo3 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("谷歌来了..."); else if(agent.contains("Firefox")) //火狐 System.out.println("火狐来了...");
    
    
    获取请求头数据3
    package
    cn.itcast.web.request; import javax.servlet.ServletContext; 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("/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);//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...");
    获取请求体数据
    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; @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
    获取其他请求参数(通用方式)
    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) 
                
                //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("-----------------");
            
    
    
        
    
        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("get");
            System.out.println(username);*/
    
            this.doPost(request,response);
        
    
    中文乱码问题
    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;
    import java.util.Enumeration;
    import java.util.Map;
    import java.util.Set;
    
    @WebServlet("/requestDemo7")
    public class RequestDemo7 extends HttpServlet 
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
            //1.设置流的编码
            request.setCharacterEncoding("utf-8");
    
            //获取请求参数username
            String username = request.getParameter("username");
    
            System.out.println(username);
        
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
    
            this.doPost(request,response);
        
    
    请求转发/共享数据
    package cn.itcast.web.request;
    
    import javax.servlet.RequestDispatcher;
    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("/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);
        
    


    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;

    @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
    package cn.itcast.web.request;
    
    import javax.servlet.ServletContext;
    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("/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);
        
    

     

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