自启动Servlet

自动启动Servlet表示在Tomcat启动时就会实例化这个Servlet，他的实例化过程不依赖于请求，而是依赖容器的启动。
可以通过在web.xml中的标签中通过1配置自启动Servlet。 值越小，优先级越高，越先执行

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
/**
 * 自启动SErvlet
 */
public class AutoStartServlet extends HttpServlet {
    @Override
    public void init() throws ServletException {
        System.out.println("autoStartServlet init......");
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        PrintWriter printWriter = resp.getWriter();
        printWriter.println("AutoStartServlet");
        printWriter.flush();
        printWriter.close();
    }
}

    <servlet>
        <servlet-name>autoStartServlet</servlet-name>
        <servlet-class>com.itbaizhan.AutoStartServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>autoStartServlet</servlet-name>
        <url-pattern>/autoStartServlet.do</url-pattern>
    </servlet-mapping>