我看书上说:Servlet只会初始化一次,在初始化的时候容器为servlet建立了ServletConfig和ServletContext。容器去web.xml中读取初始化参数,将初始化参数传递给ServletConfig和ServletContext,然后再将ServletConfig和ServletContext传递给servlet的init()方法。
假如现在有一个email项目,然后里面有一个WEB-INF/web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>email</servlet-name> <servlet-class>Email</servlet-class> <init-param> <param-name>myEmail</param-name> <param-value>Emi.wan@xxx.com</param-value> </init-param> <init-param> <param-name>adminEmail</param-name> <param-value>Admin@xxx.com</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>email</servlet-name> <url-pattern>/email.do</url-pattern> </servlet-mapping> <context-param> <param-name>managerEmail</param-name> <param-value>David.tang@xxx.com</param-value> </context-param> </web-app>
然后一个servlet----Email.java
public class Email extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("My Email is "+getServletConfig().getInitParameter("myEmail")+"<br>"); out.println("Admin\'s Email is "+getServletConfig().getInitParameter("adminEmail")+"<br>"); out.println("Manager\'s Email is "+getServletContext().getInitParameter("managerEmail")+"<br>"); } }
如果我修改了web.xml中
<init-param>和<context-param>的<param-value>值,书上说只能项目重部署的时候才能看见这个改变,可是我直接刷新几次网页(强调:一定要是几次)就看到改动的值了,不明白为什么,难道不用重部署,servlet也可以再次初始化,再次去读web.xml的初始化参数吗??我是用的MyEclipse+apache_tomcat5.5.27开发的。