(十九)、小结对18之前的
package com.Jsxs.Http; import javax.servlet.RequestDispatcher; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.*; import java.io.IOException; import java.io.InputStream; import java.net.URLDecoder; import java.util.Date; import java.util.Properties; public class Demo1 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 1.如果想要输出的数据是gbk,那么只需要resp响应头即可,可以不用设置rep。 resp.setCharacterEncoding("gbk"); req.setCharacterEncoding("UTF-8"); resp.getWriter().write(resp.getCharacterEncoding()); resp.getWriter().write("你好，我是getWriter()!"); // 2.进行设置响应界面的设置，什么界面以及编码格式 resp.setContentType("text/html;charset=UTF-8"); resp.getWriter().write(resp.getContentType()); // 3.getOutputStream和getWriter这两个方法互相排斥，调用了其中的任何一个方法后，就不能再调用另一方法。 // ServletOutputStream outputStream = resp.getOutputStream(); // outputStream.println(12123); // 4.是为了解决相对路径的问题，可返回站点的根路径。 resp.getWriter().write(req.getContextPath()); resp.getWriter().write("你好"); //=========================================================================== // ServletContext ServletContext servletContext = this.getServletContext(); // 1.存servlet和取servlet. servletContext.setAttribute("name","吉士先生"); String name = (String) servletContext.getAttribute("name"); resp.getWriter().write(name); // 2.是为了解决相对路径的问题，可返回站点的根路径。 String contextPath = servletContext.getContextPath(); resp.getWriter().write(contextPath); // 3.请求转发.... // RequestDispatcher requestDispatcher = servletContext.getRequestDispatcher("/Demo2"); // requestDispatcher.forward(req,resp); // 4.获取资源 InputStream is = servletContext.getResourceAsStream("/WEB-INF/classes/db.properties"); Properties properties = new Properties(); properties.load(is); String username = properties.getProperty("username"); String password = properties.getProperty("password"); resp.getWriter().write(URLDecoder.decode(username,"gbk")); resp.getWriter().write(password); //=========================================================================== //COOKIE /* Cookie cookie=new Cookie("Secrity","121788"); resp.addCookie(cookie); Cookie[] cookies = req.getCookies(); if (cookies==null){ resp.getWriter().write("没有cookie"); }else { for (int i = 0; i < cookies.length; i++) { Cookie cookie1 = cookies[i]; if (cookie1.getName().equals("Secrity")) { cookie1.setSecure(true); cookie1.setComment("这是您的密码"); resp.getWriter().write(cookie1.getValue()+" "+cookie1.getName()+" "+cookie1.getComment() +" "+cookie1.getPath()+" "+cookie1.getMaxAge()+" "+cookie1.getSecure()+" "+cookie1.getVersion()); } } } */ //===================================================================== // Session HttpSession session = req.getSession(); // 1.设置session并且取session session.setAttribute("GOODS","密码是:12456"); String goods = (String) session.getAttribute("GOODS"); resp.getWriter().write(goods); // 2.注销指定的session // resp.getWriter().write("结束了"); // session.invalidate(); // session.removeAttribute("GOODS"); // resp.getWriter().write(goods); // 3.获取session创建的时间: 会返回一个时间戳 long creationTime = session.getCreationTime(); resp.getWriter().write(creationTime+""); Date date = new Date(creationTime); resp.getWriter().write(date.toString()); // 4.设置和获取session的有效时间. // session.setMaxInactiveInterval(10); // resp.getWriter().write(session.getMaxInactiveInterval()); // // 5.设置ServletContext的属性，以及获取。不能获取不是ServletContext创建的属性 resp.getWriter().write("你好"); ServletContext servletContext1 = session.getServletContext(); servletContext1.setAttribute("he","吉士先生"); String goods1 = (String) servletContext1.getAttribute("he"); resp.getWriter().write(goods1); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
(二十)、过滤器、监听器常见应用
1.过滤器注册和注销操作
用户登入之后就可以进入主页，注销之后就不能进入主页
1.创建 login.jsp.里面有一个表单，表单提交后转向LoginServlet.java这个类 的映射。 2.然后映射再找对应的LoginServlet.java，进行判断。再进行重定向。
succes.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h1>主页</h1> <p><a href="Servlete/logout" >注销</a></p> </body> </html>
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>吉士先生登入界面</title> </head> <body> <form action="demo4 " method="get"> 用户名<input type="text" name="username" placeholder="请输入您的账号"> 密码<input type="password" name="password" placeholder="请输入您的密码"> <input type="submit" name="login"> <input type="reset" name="reset"> </form> </body> </html>
error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h1>您输入的信息有误</h1> <p><a href="http://localhost/Maven_Filter_war_exploded/login.jsp" >返回首页</a></p> </body> </html>
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <servlet> <servlet-name>demo2</servlet-name> <servlet-class>Servlet.Demo2</servlet-class> </servlet> <servlet-mapping> <servlet-name>demo2</servlet-name> <url-pattern>/servlet/show</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>demo2</servlet-name> <url-pattern>/servletshow</url-pattern> </servlet-mapping> <filter> <filter-name>demo1</filter-name> <filter-class>com.Jsxs.Filter.Demo1</filter-class> </filter> <filter-mapping> <filter-name>demo1</filter-name> <!-- 如果是Servlet下的所有目录，都可以用 --> <url-pattern>/succes.jsp</url-pattern> </filter-mapping> <!-- 注册监听器 --> <listener> <listener-class>Listener.OnionCount</listener-class> </listener> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>Servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/demo4</url-pattern> </servlet-mapping> <servlet> <servlet-name>logout</servlet-name> <servlet-class>Servlet.LogOut</servlet-class> </servlet> <servlet-mapping> <servlet-name>logout</servlet-name> <url-pattern>/Servlete/logout</url-pattern> </servlet-mapping> </web-app>
log.java
package Servlet; import util.Constanta; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; public class LogOut extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { HttpSession session = req.getSession(); if (session!=null){ session.removeAttribute(Constanta.USER_SESSION); System.out.println("注销成功"); resp.sendRedirect("http://localhost/Maven_Filter_war_exploded/login.jsp"); } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
