Servlet definition and method

After creating a JavaEE project, define a class and implement the Servlet interface method as:

public class ServletDemo1 implements Servlet

Servlet life cycle methods:

public class ServletDemo2 implements Servlet {
    //初始化方法
    //在Servlet被创建时执行。只会执行一次
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("init.......");
    }
    //获取ServletConfig对象
    //Servlet的配置对象
    @Override
    public ServletConfig getServletConfig() {
        return null;
    }
    //提供服务方法
    //每一次Servlet被访问时，执行。执行多次
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("service.......");
    }
    //获取Servlet的一些信息，版本、作者
    @Override
    public String getServletInfo() {
        return null;
    }
    //销毁方法
    //在服务器正常关闭时执行。执行一次
    @Override
    public void destroy() {
        System.out.println("destroy............");
    }
}

The implementation of Servlet needs to configure the path in web.xml:

<servlet>
    <servlet-name>demo1</servlet-name>
    <servlet-class>web.servlet.ServletDemo1</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>demo1</servlet-name>
    <url-pattern>/demo1</url-pattern>
</servlet-mapping>

After Servlet 3.0, it is not necessary to configure the web.xml file, and the method of configuring the Servlet is to use @WebServlet annotation:

@WebServlet("/demo")