【使用篇】之SpringBoot整合Servlet（一）

两种方式：

• 通过注解扫描完成 Servlet组件的注册
• 通过方法完成 Servlet组件的注册

一、通过注解扫描完成 Servlet 组件的注册 

1. 编写Servlet类

/**
 * SpringBoot整合Servlet方式一：
 * 
 * 传统方式：
 * <servlet>
 *         <servlet-name>FirstServlet</servlet-name> 
 *         <servlet-class>com.linhw.demo.servlet.FirstServlet</servlet-class>
 * </servlet>
 * <servlet-mapping>
 *         <servlet-name>FirstServlet</servlet-name>
 *         <url-pattern>/first</url-pattern>
 * </servlet-mapping>
 */
@WebServlet(name="FirstServlet", urlPatterns={"/first"})
public class FirstServlet extends HttpServlet{
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("FirstServlet Enter ......");
    }

}

2. 编写启动类

@SpringBootApplication
@ServletComponentScan ///在 springBoot 启动时会扫描@WebServlet，并将该类实例
public class App {

    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

二、通过方法完成 Servlet 组件的注册 

1. 编写Servlet

//与第一种的区别，就是没有加@WebServlet注解
public class SecondServlet extends HttpServlet{

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("FirstServlet Enter ......");
    }
}

2. 编写启动类

@SpringBootApplication
public class App2 {
    public static void main(String[] args) {
        SpringApplication.run(App2.class, args);
    }
    
    //以@Bean注解实例化Servlet，注入到容器中，方法名称就是bean name
    @Bean
    public ServletRegistrationBean getServlet(){
        ServletRegistrationBean secondServlet = new ServletRegistrationBean(new SecondServlet());
        secondServlet.addUrlMappings(new String[]{"/second"});
        return secondServlet;
    }
}