springboot中使用servlet原生相关功能

素颜马尾好姑娘i 2022-12-10 14:41 248阅读 0赞

## 写在前面 ##

本文介绍在springboot中使用servlet原生相关功能的方式，主要有两种：

*  注解方式  
    这种方式依赖于`@WebServlet`，`@WebFilter`,`@WebListner`等注解，需要注意，这些注意是在servlet3.0为了实现无web.xm`（注意：这是个人根据学习的猜测！！！）`正式引入的，因此想要使用的话必须是`servlet3.0及以上版本`。
 *  bean configuration方式  
    这种方式通过`springboot的XXXBean`完成相关组件的注册。

好的，那我们就正式开始吧！！！

## 1：项目创建 ##

*  ide  
    我们最爱的`idea`。
 *  构建工具  
    曾经的王者，现在逐渐被gradle取代的`maven`。
 *  jdk  
    至今还没有被后来者撼动地位的`jdk8`。
 *  springboot  
    `2.2.10.RELEASE`。

### 1.1：new->project ###

选择左侧菜单中的`Spring Initilizr`，starter选择`default`。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center]

### 1.2：录入GAV ###

根据个人录入`GAV`，选择`java8`，项目构建为\`jar,等。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 1]

### 1.3：选择依赖 ###

主要选择web下spring-web。springboot版本选择`2.2.10`。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 2]

### 1.4：finish ###

项目名称根据个人决定是否修改，正常不用管，和`ArtifactId`保持一致。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 3]

## 2：注解方式 ##

### 2.1：定义servlet ###

@WebServlet("/user/servlet")
    public class MyAnnotationServlet extends HttpServlet {
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
            resp.getWriter().write("user servlet");
        }
    }

### 2.2：定义filter ###

@WebFilter("/user/servlet")
    public class MyAnnotationFilter implements Filter {
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
            FilterChain filterChain) throws IOException, ServletException {
            System.out.println("income log filter " + servletRequest.getRemoteHost());
            filterChain.doFilter(servletRequest, servletResponse);
        }
    }

### 2.3：定义servletcontextlistener监听器 ###

@WebListener
    public class MyAnnotationServletContextListener implements ServletContextListener {
    
        @Override
        public void contextInitialized(ServletContextEvent sce) {
            System.out.println("app startup at " + LocalDateTime.now().toString());
        }
    
        @Override
        public void contextDestroyed(ServletContextEvent sce) {
        }
    }

### 2.4：启动类增加`@ServletComponentScan`注解 ###

@SpringBootApplication
    @ServletComponentScan
    public class SpringbootTestservletApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(SpringbootTestservletApplication.class, args);
        }
    
    }

### 2.5：启动并访问测试 ###

*  启动

2020-09-29 15:36:38.732  INFO 4720 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1957 ms
    app startup at 2020-09-29T15:36:38.791

*  访问测试  
    ![在这里插入图片描述][20200929153753792.jpg_pic_center]

## 3：bean configuration方式 ##

### 3.1：定义servlet ###

public class MyBeanConfigurationServlet extends HttpServlet {
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
            resp.getWriter().write("this is springboot servlet by bean configuration");
        }
    }

### 3.2：定义filter ###

public class MyBeanConfigurationFilter implements Filter {
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
            FilterChain filterChain) throws IOException, ServletException {
            System.out.println("spring boot filter by bean configuration");
            filterChain.doFilter(servletRequest, servletResponse);
        }
    
        @Override
        public void init(FilterConfig filterConfig) {
        }
    
        @Override
        public void destroy() {
        }
    }

### 3.3：定义servletcontextlistener ###

public class MyBeanConfigurationServletContextListener implements ServletContextListener {
    
        @Override
        public void contextInitialized(ServletContextEvent sce) {
            System.out.println("springboot servlet context listener by bean configuration started!");
        }
    
        @Override
        public void contextDestroyed(ServletContextEvent sce) {
        }
    }

### 3.4：定义bean configuration ###

@SpringBootConfiguration
    public class MyBeanConfiguration {
    
        // 注册servlet
        @Bean
        public ServletRegistrationBean createMyBeanConfigurationServlet() {
            ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(
                new MyBeanConfigurationServlet(), "/book.do");
            return servletRegistrationBean;
        }
    
        // 注册filter
        @Bean
        public FilterRegistrationBean createMyBeanConfigurationFilter() {
            FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
            filterRegistrationBean.setFilter(new MyBeanConfigurationFilter());
            filterRegistrationBean.setUrlPatterns(Arrays.asList("/book.do"));
            return filterRegistrationBean;
        }
    
        // 注册监听器
        @Bean
        public ServletListenerRegistrationBean createMyBeanConfigurationServletContextListener() {
            ServletListenerRegistrationBean servletListenerRegistrationBean = new ServletListenerRegistrationBean(new MyBeanConfigurationServletContextListener());
            return servletListenerRegistrationBean;
        }
    }

### 3.5：启动并测试 ###

*  启动

2020-09-29 15:57:18.374  INFO 18772 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1891 ms
    springboot servlet context listener by bean configuration started!

*  测试  
    ![在这里插入图片描述][20200929155815749.jpg_pic_center]

## 4：源码 ##

点击[这里][Link 1]。

## 最后：都让开，我要喝瑞幸 ##

![在这里插入图片描述][20200828090303329.png_pic_center]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/ea3ea166337b4849b46fa9a04b8a0b77.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/1780cc788bf8476bbcc86f456f2c0f17.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221123/f84a3ec6864b44259f97bfd643cbf9c2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 3]: /images/20221123/d73da3d377a74b4b8a41ff95538a153f.png
[20200929153753792.jpg_pic_center]: /images/20221123/240ef12d7b4746a3bc3db166b9f15b7d.png
[20200929155815749.jpg_pic_center]: /images/20221123/14885b6f1e2c44238d754e7c97bdb245.png
[Link 1]: https://gitee.com/dongsir2020/springboot-testservlet/repository/archive/master-remote.zip
[20200828090303329.png_pic_center]: /images/20221123/10bba89febb44218a04853dc06f66df3.png