先在web.xml为servlet参见初始化参数,用init-param标签
<servlet>
<description></description>
<display-name>ServletDemo3</display-name>
<servlet-name>ServletDemo3</servlet-name>
<servlet-class>cn.itcast.ServletDemo3</servlet-class>
<init-param>
<param-name>data</param-name>
<param-value>what</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>ServletDemo3</servlet-name>
<url-pattern>/ServletDemo3</url-pattern>
</servlet-mapping>
在3个方法上分别写上
public void init(ServletConfig config) throws ServletException {
this.config = config;
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String value = config.getInitParameter("data");
System.out.println(value);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
运行访问后,会在控制台看见what,即所配置的初始值