1.
2.String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path的解釋說明
這其實就是 獲得應用的根url，比如說你的應用的根路徑是 http://localhost:8080，那麼你列出的代碼就是爲basePath賦值爲 http://localhost:8080。
具體點：
1、request.getScheme() 返回協議的名稱 http，和後面的"://" 拼起來就成了 http://
2、request.getServerName() 這是獲取你的服務器的名稱，如果你的應用部署在本機那麼其就返回localhost或者127.0.0.1 ，這2個是等價的
3、request.getServerPort() 是你應用使用的端口，比如8080或者80 等等
1.
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%
response.sendRedirect(request.getContextPath()+"/user/showLogin.do");
%>
</body>
</html>
response.sendRedirect 的功能是地址重定向(頁面跳轉)
這邊重定向是/user/showLogin.do，然後去Struts-config.xml文件裏找到<action path="/user/showLogin" forward="/WEB-INF/jsp/login.jsp"/>然後跳轉到login.jsp頁面
login.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="h"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
<h1>用戶登錄<h:errors/></h1>
<hr/>
<form action="${pageContext.request.contextPath}/user/login.do" method="post">
用戶名：<input type="text" name="username"/><br/>
密碼：<input type="password" name="password"/><br/>
<input type="submit" value="登錄"/>
</form>
</body>
</html>
<action path="/user/login"
type="action.UserAction"
parameter="login"
input="/WEB-INF/jsp/login.jsp">
<exception key="exception.userNotFound" type="exception.UserNotFoundException"></exception>
<forward name="success" path="/user/selectAll.do" redirect="true"/>
</action>
action的name決定調用時的名稱；class爲實現類名；result的值爲action執行完成後轉向何頁面。如果沒有爲result指定name名稱，默認值爲success。
<exception>
path:出現異常跳轉的界面
key:異常信息的鍵
type:所要處理的異常的
UserAction.java
//登錄
public ActionForward login(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {
String username=request.getParameter("username");
String password=request.getParameter("password");
UserService userService=(UserService) ObjectFactory.getObject("userService");
userService.login(username, password);
return mapping.findForward("success");
}