JAVA-EE请求域对象的解析和请求域------计算机网络经典

淡淡的烟草味﹌ 2024-02-29 07:59 23阅读 0赞

>     Request对象实际上是一个域对象,请求域对象
>     应用域对象是什么ServletContext对象,即servlet上下文对象
>     全局都使用的,全局(webapp)共享的,内容较小,修改较少的我们就绑定在应用域之中
>     可以提高我们程序的执行效率
>     如果这个数据查询完毕后,放到了我们的servletContext中,就可以不用每次查询都去连接数据库实现查找数据
>     大大提升了查询效率(连接数据库需要从硬盘中取文件),实际上我们针对高并发的系统做法也是一样的
>     就是利用了缓存这个机制实现的提高查询效率,减少了IO的操作,大大提升了系统性能
>     线程池,字符串常量池,连接池,整数型常量池,redis,MongoDB
>     域都有这三个方法
>     void setAttribute(String name,Object obj);向域中绑定数据
>     Object setAttribute(String name);//获取域中的数据
>     void removeAttribute(String name);//将域当中的指定的数据移除
>     请求域只在一次请求内有效,尽可能使用请求域,保证这个内存占用尽可能早被清除
>     一个请求对象对应一个请求域对象
> 
> Request对象实际上是一个域对象,请求域对象  
> 应用域对象是什么ServletContext对象,即servlet上下文对象  
> 全局都使用的,全局(webapp)共享的,内容较小,修改较少的我们就绑定在应用域之中  
> 可以提高我们程序的执行效率  
> 如果这个数据查询完毕后,放到了我们的servletContext中,就可以不用每次查询都去连接数据库实现查找数据  
> 大大提升了查询效率(连接数据库需要从硬盘中取文件),实际上我们针对高并发的系统做法也是一样的  
> 就是利用了缓存这个机制实现的提高查询效率,减少了IO的操作,大大提升了系统性能  
> 线程池,字符串常量池,连接池,整数型常量池,redis,MongoDB  
> 域都有这三个方法  
> void setAttribute(String name,Object obj);向域中绑定数据  
> Object setAttribute(String name);//获取域中的数据  
> void removeAttribute(String name);//将域当中的指定的数据移除  
> 请求域只在一次请求内有效,尽可能使用请求域,保证这个内存占用尽可能早被清除  
> 一个请求对象对应一个请求域对象

> <?xml version="1.0" encoding="UTF-8"?>
> <web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"
> version="6.0">
> <servlet>
> <servlet-name>RTS</servlet-name>
> <servlet-class>com.powernode.javaweb.servlet.RequestTestServlet</servlet-class>
> </servlet>
> <servlet-mapping>
> <servlet-name>RTS</servlet-name>
> <url-pattern>/RTS</url-pattern>
> </servlet-mapping>
> <servlet>
> <servlet-name>AServlet</servlet-name>
> <servlet-class>com.powernode.javaweb.servlet.AServlet</servlet-class>
> </servlet>
> <servlet-mapping>
> <servlet-name>AServlet</servlet-name>
> <url-pattern>/AServlet</url-pattern>
> </servlet-mapping>
> <servlet>
> <servlet-name>BServlet</servlet-name>
> <servlet-class>com.powernode.javaweb.servlet.BServlet</servlet-class>
> </servlet>
> <servlet-mapping>
> <servlet-name>BServlet</servlet-name>
> <url-pattern>/BServlet</url-pattern>
> </servlet-mapping>
> <welcome-file-list>
> <welcome-file>RTS</welcome-file>
> </welcome-file-list>
> </web-app>
> 
> <?xml version="1.0" encoding="UTF-8"?>
> <web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"
> version="6.0">
> <servlet>
> <servlet-name>RTS</servlet-name>
> <servlet-class>com.powernode.javaweb.servlet.RequestTestServlet</servlet-class>
> </servlet>
> <servlet-mapping>
> <servlet-name>RTS</servlet-name>
> <url-pattern>/RTS</url-pattern>
> </servlet-mapping>
> <servlet>
> <servlet-name>AServlet</servlet-name>
> <servlet-class>com.powernode.javaweb.servlet.AServlet</servlet-class>
> </servlet>
> <servlet-mapping>
> <servlet-name>AServlet</servlet-name>
> <url-pattern>/AServlet</url-pattern>
> </servlet-mapping>
> <servlet>
> <servlet-name>BServlet</servlet-name>
> <servlet-class>com.powernode.javaweb.servlet.BServlet</servlet-class>
> </servlet>
> <servlet-mapping>
> <servlet-name>BServlet</servlet-name>
> <url-pattern>/BServlet</url-pattern>
> </servlet-mapping>
> <welcome-file-list>
> <welcome-file>RTS</welcome-file>
> </welcome-file-list>
> </web-app>

> package com.powernode.javaweb.servlet;
> 
> import jakarta.servlet.ServletException;
> import jakarta.servlet.http.*;
> 
> import java.io.IOException;
> import java.io.PrintWriter;
> import java.util.Enumeration;
> import java.util.Iterator;
> import java.util.Map;
> import java.util.Set;
> 
> public class RequestTestServlet extends HttpServlet
> {
> @Override
> protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
> response.setContentType("text/html;charset=UTF-8");
> PrintWriter out = response.getWriter();
> out.println(request);
> out.println(" ");
> out.println(response);
> out.println(" ");
> Map<String, String[]> parameterMap = request.getParameterMap();
> Set<String> strings = parameterMap.keySet();
> Iterator<String> iterator = strings.iterator();
> while (iterator.hasNext())
> {
> String next = iterator.next();
> out.println(next);
> String[] strings1 = parameterMap.get(next);
> for (int i = 0; i < strings1.length; i++) {
> out.println(strings1[i]);
> }
> out.println(" ");
> }
> Enumeration<String> parameterNames = request.getParameterNames();
> while(parameterNames.hasMoreElements())
> {
> String s = parameterNames.nextElement();
> String[] strings1 = parameterMap.get(s);
> for (int i = 0; i < strings1.length; i++) {
> out.println(strings1[i]);
> }
> out.println(" ");
> }
> String username = request.getParameter("username");
> String password = request.getParameter("password");
> String[] interests = request.getParameterValues("interest");
> for (int i = 0; i < interests.length; i++) {
> out.println(interests[i]);
> }
> }
> }
> 
> package com.powernode.javaweb.servlet;
> 
> import jakarta.servlet.ServletException;
> import jakarta.servlet.http.*;
> 
> import java.io.IOException;
> import java.io.PrintWriter;
> import java.util.Enumeration;
> import java.util.Iterator;
> import java.util.Map;
> import java.util.Set;
> 
> public class RequestTestServlet extends HttpServlet
> {
> @Override
> protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
> response.setContentType("text/html;charset=UTF-8");
> PrintWriter out = response.getWriter();
> out.println(request);
> out.println(" ");
> out.println(response);
> out.println(" ");
> Map<String, String[]> parameterMap = request.getParameterMap();
> Set<String> strings = parameterMap.keySet();
> Iterator<String> iterator = strings.iterator();
> while (iterator.hasNext())
> {
> String next = iterator.next();
> out.println(next);
> String[] strings1 = parameterMap.get(next);
> for (int i = 0; i < strings1.length; i++) {
> out.println(strings1[i]);
> }
> out.println(" ");
> }
> Enumeration<String> parameterNames = request.getParameterNames();
> while(parameterNames.hasMoreElements())
> {
> String s = parameterNames.nextElement();
> String[] strings1 = parameterMap.get(s);
> for (int i = 0; i < strings1.length; i++) {
> out.println(strings1[i]);
> }
> out.println(" ");
> }
> String username = request.getParameter("username");
> String password = request.getParameter("password");
> String[] interests = request.getParameterValues("interest");
> for (int i = 0; i < interests.length; i++) {
> out.println(interests[i]);
> }
> }
> }

>     package com.powernode.javaweb.servlet;
>     
>     import jakarta.servlet.*;
>     import jakarta.servlet.http.*;
>     
>     import java.io.IOException;
>     import java.io.PrintWriter;
>     
>     public class BServlet extends HttpServlet {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             response.setContentType("text/html;charset=UTF-8");
>             PrintWriter out = response.getWriter();
>             out.println(request.getAttribute("date"));
>         }
>     }
> 
>     package com.powernode.javaweb.servlet;
>     
>     import jakarta.servlet.*;
>     import jakarta.servlet.http.*;
>     
>     import java.io.IOException;
>     import java.io.PrintWriter;
>     
>     public class BServlet extends HttpServlet {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             response.setContentType("text/html;charset=UTF-8");
>             PrintWriter out = response.getWriter();
>             out.println(request.getAttribute("date"));
>         }
>     }

>     package com.powernode.javaweb.servlet;
>     
>     import jakarta.servlet.*;
>     import jakarta.servlet.http.*;
>     
>     import java.io.IOException;
>     import java.io.PrintWriter;
>     import java.util.Date;
>     
>     public class AServlet extends HttpServlet {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             Date date = new Date();
>             request.setAttribute("date",date);
>             response.setContentType("text/html;charset=UTF-8");
>             PrintWriter out = response.getWriter();
>             out.println(request.getAttribute("date"));
>         }
>     
>     }
> 
>     package com.powernode.javaweb.servlet;
>     
>     import jakarta.servlet.*;
>     import jakarta.servlet.http.*;
>     
>     import java.io.IOException;
>     import java.io.PrintWriter;
>     import java.util.Date;
>     
>     public class AServlet extends HttpServlet {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             Date date = new Date();
>             request.setAttribute("date",date);
>             response.setContentType("text/html;charset=UTF-8");
>             PrintWriter out = response.getWriter();
>             out.println(request.getAttribute("date"));
>         }
>     
>     }