Servlet&HTTP&Request8_Request3
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：
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