在普通的 WEB 应用中，Servlet、Filter、Listener 都是在 web.xml 配置文件中配置的。而在 Spring Boot 中，由于它省去 web.xml 配置文件，Servlet、Filter、Listener 的配置需要通过 Java 代码的方式来进行配置。

1. 通过 Bean 的方式配置

Spring Boot 提供了 ServletRegistrationBean、FilterRegistrationBean、
ServletListenerRegistrationBean 三种类型来分别配置应用的 Servlet、Filter、Listener。

# 在 Spring Boot 应用中配置使用 Servlet、Filter、Listener


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@Configuration
public class ApplicationConfigurer {
	
    @Bean
    public FilterRegistrationBean registerCustomFilter() {
        FilterRegistrationBean filterRegBean = new FilterRegistrationBean(new CustomFilter());
        filterRegBean.setUrlPatterns(Arrays.asList("/*"));
        return filterRegBean;
    }
	
    @Bean
    public ServletRegistrationBean registerCustomServlet() {
        ServletRegistrationBean servletRegBean = new ServletRegistrationBean(new CustomServlet());
        servletRegBean.setUrlMappings(Arrays.asList("/customServlet"));
        servletRegBean.setLoadOnStartup(1);
        return servletRegBean;
    }
	
    @Bean
    public ServletListenerRegistrationBean<?> registerCustomListener() {
        return new ServletListenerRegistrationBean<>(new CustomListener());
    }
	
}

# 自定义的 Filter


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public class CustomFilter implements Filter {
    
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("------ CustomFilter ------");
        chain.doFilter(request, response);
    }
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    
    }
    
    @Override
    public void destroy() {
    
    }
    
}

# 自定义的 Listener


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public class CustomListener implements ServletRequestListener {
	
    @Override
    public void requestInitialized(ServletRequestEvent event) {
        System.out.println("------ CustomListener ------");
    }
	
    @Override
    public void requestDestroyed(ServletRequestEvent event) {
    
    }
	
}

# 自定义的 Servlet


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public class CustomServlet extends HttpServlet {
	
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("------ CustomServlet ------");
    }
	
}

2. 通过注解的方式配置

Spring Boot 提供了 @WebServlet、@WebFilter、@WebListener 三种类型的注解来分别配置应用的 Servlet、Filter、Listener。

# Filter 注解


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@WebFilter(urlPatterns = "/*")
public class CustomFilter implements Filter {
	
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("------ CustomFilter Annotation ------");
        chain.doFilter(request, response);
    }
	
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    
    }
	
    @Override
    public void destroy() {
    
    }
	
}

# Listener 注解


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@WebListener
public class CustomListener implements ServletRequestListener {
	
    @Override
    public void requestInitialized(ServletRequestEvent event) {
        System.out.println("------ CustomListener Annotation ------");
    }
	
    @Override
    public void requestDestroyed(ServletRequestEvent event) {
    
    }
	
}

# Servlet 注解


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@WebServlet(urlPatterns = "/customServlet", loadOnStartup = 1)
public class CustomServlet extends HttpServlet {
	
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("------ CustomServlet Annotation ------");
    }
	
}

最后，需要在应用中使用@ServletComponentScan注解配置才有效。

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

示例项目开发环境：Java-8、Maven-3、IntelliJ IDEA-2017、Spring Boot-1.5.2.RELEASE
完整示例项目链接：conf-sample scan-sample
参考文档文献链接：http://docs.spring.io/spring-boot/docs/1.5.2.RELEASE/reference/htmlsingle/#boot-features-embedded-container