Request 的学习
Posted yanzhudl
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- 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 - 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)
- 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
】 - 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()
】 - 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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