目前来说,初学ServletContext对象,有几个应用你肯定要知道:
(1)获取整个web站点的初始化参数
a:就是在web.xml文件中的<servlet>标签之外配置<context-param>标签
<context-param>
<param-name>url</param-name>
<param-value>jdbc:mysql://localhost:3306/test</param-value>
</context-param>
b:在任何servletDemo中获取数据
ServletContext context = this.getServletContext();
String url = context.getInitParameter("url");
System.out.println(url);
(2)多个servlet通过servletContext实现数据共享
a:在servletDemo1中
String data = "abcddffdf";
ServletContext context = this.getServletConfig().getServletContext();
context.setAttribute("data", data); //map
b:在servletDemo2中获取数据
ServletContext context = this.getServletContext();
String data = (String) context.getAttribute("data");
System.out.println(data);
(3)用servletContext实现请求转发:mvc
a:在servletDemo3写转发
ServletContext context = this.getServletContext();
RequestDispatcher rd = context.getRequestDispatcher("/servlet/ServletContextDemo4");
rd.forward(request, response); //doget()
b:在servletDemo4中处理
response.getOutputStream().write("servletDemo5".getBytes());
(4)使用servletContext读取资源文件
请查看 web工程下如何读取资源文件!!!