public class Servlet1 implements Servlet {
  @Override
  public void init(ServletConfig config) throws ServletException {

  }

  @Override
  public ServletConfig getServletConfig() {
    return null;
  }

  @Override
  public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
    //返回到瀏覽器
    res.getWriter().write("hello servlet");

  }

  @Override
  public String getServletInfo() {
    return null;
  }

  @Override
  public void destroy() {

  }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
     xmlns="http://java.sun.com/xml/ns/javaee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
  http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
 <display-name></display-name>

<servlet>
 <!--定義一個serlvet-->
 <servlet-name>servlet1</servlet-name>
 <servlet-class>com.rookie.bigdata.Servlet1</servlet-class>
</servlet>

 <!--對servlet進行映射-->
 <servlet-mapping>
  <servlet-name>servlet1</servlet-name>
  <url-pattern>/servlet1</url-pattern>
 </servlet-mapping>



 <welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
</web-app>