servlet主要用负责web程序中的逻辑处理，属于MVC三层结构中的C(control)层，一般来讲一次请求会对应有一个servlet类，eclipse中可以直接创建servlet类
1.新建servlet
2.填写Class名：
3.设定访问路径
4.点击完成后生成如下代码：
@WebServlet("/Upload")
public class Upload extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Upload() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
然后在doGet()方法中编写代码。
5.session和application用如下代码获得：
ServletContext application = this.getServletContext(); HttpSession session = request.getSession();