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
HttpServletRequest -- 接口,继承ServletRequest(public interface HttpServletRequest extends ServletRequest )
org.apache.catalina.connector.RequestFacade,这是一个实现类(tomcat编写的,public class RequestFacade implements HttpServletRequest),tomcat将来通过这个类来创建HttpServletRequest对象并传递给service方法。
3、request功能
1. 获取请求消息数据
a. 获取请求行数据
* 请求行格式:GET /day14/demo1?name=zhangsan&age=12 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&age=12
* 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(代表的范围更大):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(IPV6的格式):
* String getRemoteAddr()
* 演示:
idea中新建cn.itcase.web.request,request包右键New Servlet
新建servlet后自动生成代码如下
练习方法
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 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); } }
提前修改tomcat端口号为80,虚拟路径为/day08(Deployment->Application Context),浏览器访问http://localhost/day08/requestDemo1?name=zhangsan&age=12,输出结果:
b. 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
* 演示1:
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); } } }
浏览器访问http://localhost/day08/requestDemo2,输出结果
* 演示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")){ System.out.println("谷歌来了。。。"); }else if(agent.contains("Firefox")){ System.out.println("火狐来了。。。"); } } }
谷歌浏览器访问http://localhost/day08/requestDemo3,然后火狐浏览器访问http://localhost/day08/requestDemo2,输出结果:
* 演示3:
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("/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("/day08")){ //正常访问 System.out.println("播放电影。。。"); }else{ //盗链 System.out.println("想看电影吗?来优酷吧。。。"); } } } }
浏览器访问http://localhost/day08/requestDemo4,输出结果:null
web包中新增login.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <a href="/day08/requestDemo4">demo4...</a> </body> </html>
浏览器访问http://localhost/day08/login.html,显示demo4...,点击demo4,检查idea控制台输出结果:
day07_servlet module中web包中新建index.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <a href="http://localhost/day08/requestDemo4">高清电影</a> </body> </html>
更改tomcat配置(Deployment选择day07的包并更改Application Context为/day07),重启tomcat,浏览器访问http://localhost/day07
点击“高清电影”,检查idea控制台输出结果:
* 演示4:
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("/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/day08/login.html //防盗链 if(referer != null){ if(referer.contains("/day08")){ //正常访问 response.setContentType("text/html;charset=utf-8"); response.getWriter().write("播放电影..."); }else{ //盗链 response.setContentType("text/html;charset=utf-8"); response.getWriter().write("想看电影吗?来优酷吧。。。"); } } } }
重启tomcat,访问http://localhost/day07,点击高清电影,检查浏览器结果;访问http://localhost/day08/login.html,点击demo4,检查浏览器结果
c. 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(ServletInputStream extends InputStream)
* 在文件上传知识点后讲解
2. 再从流对象中拿数据
* 演示1:
web包下新建regist.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action ="/day08/requestDemo5" method="post">
<input type="text" placeholder="请输入用户名" name="username"><br>
<input type="text" placeholder="请输入密码" name="password"><br>
<input type="submit" value="注册">
</form>
</body>
</html>
src下的cn.itcast.web.request包下新建Servlet:RequestDemo5
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 { } }
浏览器访问http://localhost/day08/regist.html,检查浏览器响应
输入用户名和密码,点击“注册”,检查idea控制台输出结果:username=zhangsan&password=123
2. 其他功能:
a. 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
* 演示1:
web包下新建regist2.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action ="/day08/requestDemo6" method="post"> <input type="text" placeholder="请输入用户名" name="username"><br> <input type="text" placeholder="请输入密码" name="password"><br> <input type="submit" value="注册"> </form> </body> </html>
src下的cn.itcast.web.request包中新建Servlet:RequestDemo6.java
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("/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); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //get 获取请求参数 String username = request.getParameter("username"); System.out.println("get"); System.out.println(username); } }
浏览器访问http://localhost/day08/regist2.html,输入用户名和密码,点击注册,检查idea控制台输出结果:
更改regist2.html中的method为get,浏览器重新访问http://localhost/day08/regist2.html,输入用户名和密码,点击注册,检查idea控制台输出结果:
由此可知getParameter()方法是get/post通用的方法,因此可以简化代码
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("/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); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //get 获取请求参数 this.doPost(request,response); } }
* 演示2:
修改regist2.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action ="/day08/requestDemo6" method="get"> <input type="text" placeholder="请输入用户名" name="username"><br> <input type="text" placeholder="请输入密码" name="password"><br> <input type="checkbox" name="hobby" value="game">游戏 <input type="checkbox" name="hobby" value="study">学习 <br> <input type="submit" value="注册"> </form> </body> </html>
修改RequestDemo6.java
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("/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的数据
String[] hobbies = request.getParameterValues("hobby");
for (String hobby : hobbies) {//iter的快捷方式
System.out.println(hobby);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//get 获取请求参数
this.doPost(request,response);
}
}
浏览器访问http://localhost/day08/regist2.html,浏览器展示
选中游戏和学习的复选框,点击“注册”,检查idea控制台输出结果:game study
* 演示3:
修改RequestDemo6.java
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; @WebServlet("/requestDemo6") public class RequestDemo6 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //post 获取请求参数 //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("-----------"); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //get 获取请求参数 this.doPost(request,response); } }
浏览器访问http://localhost/day08/regist2.html,输入用户名、密码并勾选游戏和学习,点击“注册”,检查idea控制台输出结果:
可以看到getParameter()只能获取一个值。
* 演示4:
修改RequestDemo6.java
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 //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){ //根据key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 this.doPost(request,response); } }
浏览器访问http://localhost/day08/regist2.html,输入用户名、密码并勾选游戏和学习,点击“注册”,检查idea控制台输出结果:
* 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");
b. 请求转发:一种在服务器内部的资源跳转方式
1. 步骤:
i. 通过request对象获取请求转发器对象:RequestDispatcher getRequestDispatcher(String path),path为servlet path。
ii. 使用RequestDispatcher对象来进行转发:forward(ServletRequest request, ServletResponse response)
2. 特点:
i. 浏览器地址栏路径不发生变化
ii. 只能转发到当前服务器内部资源中。例如:不能转发到百度。
iii. 转发是一次请求(可通过F12中的network去验证)。
* 演示1:
src下的cn.itcast.web.request包中新建servlet:RequestDemo8、RequestDemo9
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("demo8被访问了。。。"); //转发到demo9资源 /* RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9"); requestDispatcher.forward(request,response);*/ request.getRequestDispatcher("/requestDemo9").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 { System.out.println("demo9被访问了。。。"); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }
浏览器访问http://localhost/day08/requestDemo8,idea控制台输出结果,同时浏览器的地址栏的路径仍旧是http://localhost/day08/requestDemo8
c. 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
* 演示
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("demo8被访问了。。。"); //转发到demo9资源 //存储数据到request域中 request.setAttribute("msg","hello"); request.getRequestDispatcher("/requestDemo9").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("demo9被访问了。。。"); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }
重启tomcat服务器,浏览器访问http://localhost/day08/requestDemo8,检查idea控制台输出结果:
d. 获取ServletContext:ServletContext getServletContext()
*演示:
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); } }
重启tomcat服务器,浏览器访问http://localhost/day08/requestDemo10,检查idea控制台输出结果: