浅谈入门Servlet注解式开发

Servlet3.0版本之后，推出了Servlet基于注解式开发。
优点：开发效率高，直接在java类上使用注解进行标注
import javax.servlet.annotation.WebServlet;

@WebServlet

@WebServlet的属性
name属性：用来指定Servlet的名字 == <servlet-name>
urlPatterns属性：用来指定Servlet的映射路径。可以指定多个路径 == <url-pattern>
loadOnstartUp属性：用来指定在服务器启动阶段是否加载该类。 == <load-on-startup>
value属性：和urlPatterns属性一样，都是用来指定Servlet映射路径(若使用value，则属性名可以省略)

@WebServlet(name ="demo" ,urlPatterns = {"/qgs/demoServlet1","/qgs/demoServlet2"}, loadOnStartup = 1,
        initParams = {@WebInitParam(name ="demo1",value = "111"),@WebInitParam(name ="demo2",value = "222")})
public class DemoServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        //获取初始化参数
        Enumeration<String> Names = request.getParameterNames();
        while (Names.hasMoreElements()) {
            String name = Names.nextElement();
            String value = getInitParameter(name);
        }
        out.print("hello world :"+request.getContextPath());
    }
}