# spring boot 整合 servlet ## 一、说明 #### 1.1 项目结构说明 1. 项目提供与servlet整合的两种方式,一种是servlet3.0 原生的注解方式,一种是采用spring 注册的方式; 2. servlet、过滤器、监听器分别位于servlet、filter、listen 下,其中以Annotation命名结尾的代表是servlet注解方式实现,采用spring注册方式则在ServletConfig中进行注册; 3. 为了说明外置容器对servlet注解的自动发现机制,项目采用外置容器构建,关于spring boot 整合外置容器的详细说明可以参考[spring-boot-tomcat](https://github.com/heibaiying/spring-samples-for-all/tree/master/spring-boot/spring-boot-tomcat)
#### 1.2 项目依赖 ```xml org.springframework.boot spring-boot-starter-web org.springframework.boot spring-boot-starter-tomcat javax.servlet servlet-api 2.5 provided javax.servlet javax.servlet-api ``` ## 二、采用spring 注册方式整合 servlet #### 2.1 新建过滤器、监听器和servlet ```java /** * @author : heibaiying * @description : 自定义过滤器 */ public class CustomFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { request.setAttribute("filterParam","我是filter传递的参数"); chain.doFilter(request,response); response.getWriter().append(" CustomFilter "); } @Override public void destroy() { } } ``` ```java /** * @author : heibaiying * @description : 自定义监听器 */ public class CustomListen implements ServletContextListener { //Web应用程序初始化过程正在启动的通知 @Override public void contextInitialized(ServletContextEvent sce) { System.out.println("容器初始化启动"); } /* 通知servlet上下文即将关闭 * 这个地方如果我们使用的是spring boot 内置的容器 是监听不到销毁过程,所以我们使用了外置 tomcat 容器 */ @Override public void contextDestroyed(ServletContextEvent sce) { System.out.println("容器即将销毁"); } } ``` ```java /** * @author : heibaiying * @description : 自定义servlet */ public class CustomServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { System.out.println("doGet 执行:" + req.getAttribute("filterParam")); resp.getWriter().append("CustomServlet"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } } ``` #### 2.2 注册过滤器、监听器和servlet ```java /** * @author : heibaiying */ @Configuration public class ServletConfig { @Bean public ServletRegistrationBean registrationBean() { return new ServletRegistrationBean(new CustomServlet(), "/servlet"); } @Bean public FilterRegistrationBean filterRegistrationBean() { FilterRegistrationBean bean = new FilterRegistrationBean(); bean.setFilter(new CustomFilter()); bean.addUrlPatterns("/servlet"); return bean; } @Bean public ServletListenerRegistrationBean listenerRegistrationBean() { return new ServletListenerRegistrationBean(new CustomListen()); } } ``` ## 三、采用注解方式整合 servlet #### 3.1 新建过滤器、监听器和servlet,分别使用@WebFilter、@WebListener、@WebServlet注解标注 ```java /** * @author : heibaiying * @description : 自定义过滤器 */ @WebFilter(urlPatterns = "/servletAnn") public class CustomFilterAnnotation implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { chain.doFilter(request,response); response.getWriter().append(" CustomFilter Annotation"); } @Override public void destroy() { } } ``` ```java /** * @author : heibaiying * @description :自定义监听器 */ @WebListener public class CustomListenAnnotation implements ServletContextListener { //Web应用程序初始化过程正在启动的通知 @Override public void contextInitialized(ServletContextEvent sce) { System.out.println("容器初始化启动 Annotation"); } /* 通知servlet上下文即将关闭 * 这个地方如果我们使用的是spring boot 内置的容器 是监听不到销毁过程,所以我们使用了外置 tomcat 容器 */ @Override public void contextDestroyed(ServletContextEvent sce) { System.out.println("容器即将销毁 Annotation"); } } ``` ```java /** * @author : heibaiying * @description : 自定义servlet */ @WebServlet(urlPatterns = "/servletAnn") public class CustomServletAnnotation extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.getWriter().append("CustomServlet Annotation"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } } ``` #### 3.2 使注解生效 1. 如果是内置容器,需要在启动类上添加@ServletComponentScan("com.heibaiying.springbootservlet") ,指定扫描的包目录; 2. 如果是外置容器,不需要进行任何配置,依靠容器内建的discovery机制自动发现,需要说明的是这里的容器必须支持servlet3.0(tomcat从7.0版本开始支持Servlet3.0)。