jspweb里面用到的servlet跳转页面的方法
使用的jar包只有
commons-lang3-3.5.jar
运行时，tomcat会先根据web.xml里面的信息，查找servlet
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>servlet</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>servlet</servlet-name> <servlet-class>com.javaweb.action.Servlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>servlet</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> </web-app>
<servlet> 就是你注册的servlet和他的物理地址
<servlet-mapping>servlet的相对地址，就是在.jsp中怎么用
然后就是根据欢迎页面index.jsp等待用户操作
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <% String path = request.getContextPath();// 获得当前的项目根目录路径 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path; //完整路径 %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>这是首页</title> </head> <body> <table border=0 cellpadding=0 cellspacing=0 style="margin:auto;border-collapse:separate; border-spacing:10px;"> <tr> <td> servlet根目录路径:<%out.print(path);%> </td> </tr> <tr> <td> servlet完整路径:<%out.print(basePath);%> </td> </tr> <tr> <td> <!--后缀名是.do的直接根据目录找到first方法--> <a href="<%=basePath%>/first.do">第一的英文</a> </td> </tr> <tr> <td> <!--?的是--> <a href="<%=basePath%>/.do?op=second">第二的英文</a> </td> </tr> <tr> <td> <!--触发？的else选项，常用来放错误信息--> <a href="<%=basePath%>/.do?op=WOSUIBIANDADE">第三的英文</a> </td> </tr> </table> </body> </html>
servlet的具体响应
package com.javaweb.action; import java.io.IOException; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.lang3.StringUtils; public class Servlet extends HttpServlet{ /** * 用于版本控制 */ private static final long serialVersionUID = -2357925750878300415L; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub //纯碎是用来判断有没有错误 String url=req.getServletPath(); String method=url.substring(1,url.lastIndexOf(".")); try { Method met=getClass().getDeclaredMethod(method, HttpServletRequest.class,HttpServletResponse.class); try { met.invoke(this, req,resp); } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { e.printStackTrace(); } } catch (NoSuchMethodException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } //使用？跳转页面 req.setCharacterEncoding("UTF-8"); String op=req.getParameter("op"); if(StringUtils.isNotBlank(op)){ if("second".equalsIgnoreCase(op)){ second(req, resp); }else{ PrintWriter out=resp.getWriter();//调用窗口
out.println("THIRD");
} } } public void first(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.sendRedirect("first.jsp"); } public void second(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.sendRedirect("second.jsp"); } }
显然用？的方法和用.do的方法都能实现同样的功能
但是在大量方法同时存在的时候？方法可以用于区分不同方面的方法
req.getParameter("login");
req.getParameter("logout");....
结果
