getInitParameter方法
???? 在ServletConfig和ServletContext都有getInitParameter方法，?这两个方法的都能从web.xml中获取参数，但是是有区别的。
??? 1. web.xml文件
<?xml version="1.0" encoding="UTF-8"?><web-app id="WebApp_ID" version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"><context-param> <param-name>webParam</param-name> <param-value>aaa</param-value></context-param><servlet><servlet-name>test</servlet-name><servlet-class>Test</servlet-class><init-param> <param-name>servletParam</param-name> <param-value>bbb</param-value></init-param></servlet><servlet-mapping><servlet-name>test</servlet-name><url-pattern>/test</url-pattern></servlet-mapping></web-app>
???? 注：区分配置文件中，对参数的配置的不同.?servletParam这个参数是属于Test这个Servlet的; 而webParam这个参数是属于web应用的，被各个servlet共享。
??? 2. 调用代码
public class Test extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out = response.getWriter();String s1 = this.getInitParameter("servletParam");String s2 = this.getServletContext().getInitParameter("webParam");//注意区别，一个是独属于Test这个Servlet的参数，一个是web范围的参数，out.println("<HTML>");out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");out.println(" <BODY>");out.println(s1);out.println(s2);out.println(" </BODY>");out.println("</HTML>");out.flush();out.close();}}?
????3. 运行结果
? ? bbb aaa