9639322.html

https://blog.csdn.net/qq_38709999/article/details/99986797

SpringBoot 配置 Servlet、Filter、Listener

在SpringBoot应用中，嵌入式的 Servlet 3.0+ 容器不会直接使用 ServletContainerInitializer 和 WebApplicationInitializer，即通过以上两个接口实现的 Servlet、Filter、Listener 配置都是无效的，这是为了防止第三方代码的设计损坏应用程序，原文如下

Embedded servlet containers will not directly execute the Servlet 3.0+ javax.servlet.ServletContainerInitializer interface, or Spring’s org.springframework.web.WebApplicationInitializer interface. This is an intentional design decision intended to reduce the risk that 3rd party libraries designed to run inside a war will break Spring Boot applications.

If you need to perform servlet context initialization in a Spring Boot application, you should register a bean that implements the org.springframework.boot.context.embedded.ServletContextInitializer interface. The single onStartup method provides access to the ServletContext, and can easily be used as an adapter to an existing WebApplicationInitializer if necessary.

综上，可以采取以下配置

配置策略一：ServletContextInitializer

由官方原文可知，我们可以使用替代方案：ServletContextInitializer，示例如下

@Configuration
public class GoServletContextInitializer implements ServletContextInitializer { @Override public void onStartup(ServletContext servletContext) throws ServletException { //配置 Log4j Config Listener servletContext.setInitParameter("log4jConfigLocation", "classpath:config/properties/log4j.properties"); servletContext.addListener(Log4jConfigListener.class); //配置 CharacterEncodingFilter FilterRegistration.Dynamic characterEncodingFilter = servletContext.addFilter("characterEncodingFilter", CharacterEncodingFilter.class); characterEncodingFilter.setInitParameter("encoding", "UTF-8"); characterEncodingFilter.setInitParameter("forceEncoding", "true"); characterEncodingFilter.addMappingForUrlPatterns( EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE), false, "/*"); //配置 statViewServlet StatViewServlet statViewServlet = new StatViewServlet(); ServletRegistration.Dynamic dynamic = servletContext.addServlet( "statViewServlet", statViewServlet); dynamic.setLoadOnStartup(2); dynamic.addMapping("/druid/*"); } }

亲测，即使将 Spring Boot 打包成 war，并部署到 Tomcat 8.5，这份配置也是有效的

配置策略二：ServletContextInitializer 的延伸

请看类继承体系

原理：最下边的三个子类会自动在运行时注册 Servlet、Listener、Filter（一定要将其定义为 Spring 容器的 Bean）

ServletRegistrationBean：在Servlet容器初始化时，向 ServletContext 注册一个自定义的 Servlet
ServletListenerRegistrationBean：在Servlet容器初始化时，向 ServletContext 注册一个自定义的 ServletContextListener
AbstractFilterRegistrationBean：（模板方法模式）通过模板方法 getFilter()，将 Filter 的构建过程延迟到子类，并在Servlet容器初始化时，向 ServletContext 注册该 Filter。开发者可以定义一个子类来重写该模板方法，以配置一个自定义的 Filter。

Servlet 配置示例

@Configuration
public class ServletConfig { //配置 StatViewServlet @Bean public ServletRegistrationBean servletRegistration0() { ServletRegistrationBean registration = new ServletRegistrationBean(new StatViewServlet()); registration.addUrlMappings("/druid/*"); registration.setLoadOnStartup(0); return registration; } }

Filter 配置示例

@Configuration
public class FilterConfig { //配置 CharacterEncodingFilter @Bean public FilterRegistrationBean filterRegistration1() { FilterRegistrationBean registration = new FilterRegistrationBean(new CharacterEncodingFilter()); registration.addUrlPatterns("/*"); Map<String, String> initParameters = Maps.newHashMap(); initParameters.put("encoding", "UTF-8"); initParameters.put("forceEncoding", "true"); registration.setInitParameters(initParameters); return registration; } }

Listener 配置示例

@Configuration
public class ListenerConfig { //配置 RequestContextListener @Bean public ServletListenerRegistrationBean<RequestContextListener> listenerRegistration3() { return new ServletListenerRegistrationBean<>( new RequestContextListener()); } }

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需求：springboot 启动后自动执行某些代码，初始化数据，并将数据放到 servletContext 中。

首先，不可使用 ServletContextListener 即不能用 @WebListener ，因为 servlet 容器初始化后，spring 并未初始化完毕，不能使用 @Autowired 注入 spring 的对象。

推荐使用 ApplicationListener：启动项目， spring 加载完毕后，才执行该 ApplicationListener，并且该 Listener 中可以使用 spring 的内容。

@Component
public class SettingDataInitListener implements ApplicationListener<ContextRefreshedEvent> {
    @Override
    public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
        // 将 ApplicationContext 转化为 WebApplicationContext 
        WebApplicationContext webApplicationContext = 
            (WebApplicationContext)contextRefreshedEvent.getApplicationContext();
        // 从 webApplicationContext 中获取  servletContext 
        ServletContext servletContext = webApplicationContext.getServletContext();
        // servletContext设置值
        servletContext.setAttribute("key", "value");
    }

需求：springboot 启动后自动执行某些代码，初始化数据，并将数据放到 servletContext 中。

首先，不可使用 ServletContextListener 即不能用 @WebListener ，因为 servlet 容器初始化后，spring 并未初始化完毕，不能使用 @Autowired 注入 spring 的对象。

推荐使用 ApplicationListener：启动项目， spring 加载完毕后，才执行该 ApplicationListener，并且该 Listener 中可以使用 spring 的内容。

@Component
public class SettingDataInitListener implements ApplicationListener<ContextRefreshedEvent> {
@Override
public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
// 将 ApplicationContext 转化为 WebApplicationContext
WebApplicationContext webApplicationContext =
(WebApplicationContext)contextRefreshedEvent.getApplicationContext();
// 从 webApplicationContext 中获取 servletContext
ServletContext servletContext = webApplicationContext.getServletContext();
// servletContext设置值
servletContext.setAttribute( "key", "value");
}

Embedded servlet containers will not directly execute the Servlet 3.0+ javax.servlet.ServletContainerInitializer interface, or Spring’s org.springframework.web.WebApplicationInitializer interface. This is an intentional design decision intended to reduce the risk that 3rd party libraries designed to run inside a war will break Spring Boot applications.

If you need to perform servlet context initialization in a Spring Boot application, you should register a bean that implements the org.springframework.boot.context.embedded.ServletContextInitializer interface. The single onStartup method provides access to the ServletContext, and can easily be used as an adapter to an existing WebApplicationInitializer if necessary.

综上，可以采取以下配置

配置策略一：ServletContextInitializer

由官方原文可知，我们可以使用替代方案：ServletContextInitializer，示例如下

@Configuration
public class GoServletContextInitializer implements ServletContextInitializer { @Override public void onStartup(ServletContext servletContext) throws ServletException { //配置 Log4j Config Listener servletContext.setInitParameter("log4jConfigLocation", "classpath:config/properties/log4j.properties"); servletContext.addListener(Log4jConfigListener.class); //配置 CharacterEncodingFilter FilterRegistration.Dynamic characterEncodingFilter = servletContext.addFilter("characterEncodingFilter", CharacterEncodingFilter.class); characterEncodingFilter.setInitParameter("encoding", "UTF-8"); characterEncodingFilter.setInitParameter("forceEncoding", "true"); characterEncodingFilter.addMappingForUrlPatterns( EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE), false, "/*"); //配置 statViewServlet StatViewServlet statViewServlet = new StatViewServlet(); ServletRegistration.Dynamic dynamic = servletContext.addServlet( "statViewServlet", statViewServlet); dynamic.setLoadOnStartup(2); dynamic.addMapping("/druid/*"); } }

亲测，即使将 Spring Boot 打包成 war，并部署到 Tomcat 8.5，这份配置也是有效的

配置策略二：ServletContextInitializer 的延伸

请看类继承体系

原理：最下边的三个子类会自动在运行时注册 Servlet、Listener、Filter（一定要将其定义为 Spring 容器的 Bean）

ServletRegistrationBean：在Servlet容器初始化时，向 ServletContext 注册一个自定义的 Servlet
ServletListenerRegistrationBean：在Servlet容器初始化时，向 ServletContext 注册一个自定义的 ServletContextListener
AbstractFilterRegistrationBean：（模板方法模式）通过模板方法 getFilter()，将 Filter 的构建过程延迟到子类，并在Servlet容器初始化时，向 ServletContext 注册该 Filter。开发者可以定义一个子类来重写该模板方法，以配置一个自定义的 Filter。

Servlet 配置示例

@Configuration
public class ServletConfig { //配置 StatViewServlet @Bean public ServletRegistrationBean servletRegistration0() { ServletRegistrationBean registration = new ServletRegistrationBean(new StatViewServlet()); registration.addUrlMappings("/druid/*"); registration.setLoadOnStartup(0); return registration; } }

Filter 配置示例

@Configuration
public class FilterConfig { //配置 CharacterEncodingFilter @Bean public FilterRegistrationBean filterRegistration1() { FilterRegistrationBean registration = new FilterRegistrationBean(new CharacterEncodingFilter()); registration.addUrlPatterns("/*"); Map<String, String> initParameters = Maps.newHashMap(); initParameters.put("encoding", "UTF-8"); initParameters.put("forceEncoding", "true"); registration.setInitParameters(initParameters); return registration; } }

Listener 配置示例

@Configuration
public class ListenerConfig { //配置 RequestContextListener @Bean public ServletListenerRegistrationBean<RequestContextListener> listenerRegistration3() { return new ServletListenerRegistrationBean<>( new RequestContextListener()); } }

SpringBoot 配置 Servlet、Filter、Listener

https://www.cnblogs.com/pomer-huang/p/9639322.html

SpringBoot 配置 Servlet、Filter、Listener

配置策略一：ServletContextInitializer

配置策略二：ServletContextInitializer 的延伸

配置策略一：ServletContextInitializer

配置策略二：ServletContextInitializer 的延伸

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