246 lines
7.9 KiB
Markdown
246 lines
7.9 KiB
Markdown
# spring boot 整合 servlet
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## 目录<br/>
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<a href="#一说明">一、说明</a><br/>
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<a href="#11-项目结构说明">1.1 项目结构说明</a><br/>
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<a href="#12-项目依赖">1.2 项目依赖</a><br/>
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<a href="#二采用spring-注册方式整合-servlet">二、采用spring 注册方式整合 servlet</a><br/>
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<a href="#21-新建过滤器监听器和servlet">2.1 新建过滤器、监听器和servlet</a><br/>
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<a href="#22-注册过滤器监听器和servlet">2.2 注册过滤器、监听器和servlet</a><br/>
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<a href="#三采用注解方式整合-servlet">三、采用注解方式整合 servlet</a><br/>
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<a href="#31-新建过滤器监听器和servlet分别使用WebFilterWebListenerWebServlet注解标注">3.1 新建过滤器、监听器和servlet,分别使用@WebFilter、@WebListener、@WebServlet注解标注</a><br/>
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<a href="#32-使注解生效">3.2 使注解生效</a><br/>
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## 正文<br/>
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## 一、说明
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#### 1.1 项目结构说明
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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；
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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；
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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)
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<div align="center"> <img src="https://github.com/heibaiying/spring-samples-for-all/blob/master/pictures/spring-boot-servlet.png"/> </div>
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#### 1.2 项目依赖
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```xml
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<dependencies>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-web</artifactId>
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<!--排除依赖 使用外部 tomcat 容器启动-->
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<exclusions>
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<exclusion>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-tomcat</artifactId>
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</exclusion>
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</exclusions>
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</dependency>
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<dependency>
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<!--使用外置容器时候 SpringBootServletInitializer 依赖此包 -->
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<groupId>javax.servlet</groupId>
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<artifactId>servlet-api</artifactId>
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<version>2.5</version>
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<scope>provided</scope>
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</dependency>
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<!--servlet api 注解依赖包-->
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<dependency>
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<groupId>javax.servlet</groupId>
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<artifactId>javax.servlet-api</artifactId>
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</dependency>
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</dependencies>
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```
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## 二、采用spring 注册方式整合 servlet
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#### 2.1 新建过滤器、监听器和servlet
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```java
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/**
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* @author : heibaiying
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* @description : 自定义过滤器
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*/
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public class CustomFilter implements Filter {
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@Override
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public void init(FilterConfig filterConfig) throws ServletException {
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}
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@Override
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public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
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request.setAttribute("filterParam","我是 filter 传递的参数");
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chain.doFilter(request,response);
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response.getWriter().append(" CustomFilter ");
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}
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@Override
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public void destroy() {
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}
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}
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```
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```java
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/**
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* @author : heibaiying
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* @description : 自定义监听器
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*/
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public class CustomListen implements ServletContextListener {
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//Web 应用程序初始化过程正在启动的通知
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@Override
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public void contextInitialized(ServletContextEvent sce) {
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System.out.println("容器初始化启动");
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}
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/* 通知 servlet 上下文即将关闭
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* 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
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*/
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@Override
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public void contextDestroyed(ServletContextEvent sce) {
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System.out.println("容器即将销毁");
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}
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}
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```
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```java
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/**
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* @author : heibaiying
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* @description : 自定义 servlet
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*/
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public class CustomServlet extends HttpServlet {
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@Override
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protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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System.out.println("doGet 执行：" + req.getAttribute("filterParam"));
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resp.getWriter().append("CustomServlet");
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}
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@Override
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protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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doGet(req, resp);
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}
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}
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```
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#### 2.2 注册过滤器、监听器和servlet
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```java
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/**
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* @author : heibaiying
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*/
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@Configuration
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public class ServletConfig {
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@Bean
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public ServletRegistrationBean registrationBean() {
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return new ServletRegistrationBean<HttpServlet>(new CustomServlet(), "/servlet");
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}
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@Bean
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public FilterRegistrationBean filterRegistrationBean() {
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FilterRegistrationBean bean = new FilterRegistrationBean<Filter>();
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bean.setFilter(new CustomFilter());
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bean.addUrlPatterns("/servlet");
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return bean;
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}
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@Bean
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public ServletListenerRegistrationBean listenerRegistrationBean() {
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return new ServletListenerRegistrationBean<ServletContextListener>(new CustomListen());
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}
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}
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```
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## 三、采用注解方式整合 servlet
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#### 3.1 新建过滤器、监听器和servlet,分别使用@WebFilter、@WebListener、@WebServlet注解标注
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```java
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/**
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* @author : heibaiying
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* @description : 自定义过滤器
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*/
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@WebFilter(urlPatterns = "/servletAnn")
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public class CustomFilterAnnotation implements Filter {
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@Override
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public void init(FilterConfig filterConfig) throws ServletException {
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}
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@Override
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public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
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chain.doFilter(request,response);
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response.getWriter().append(" CustomFilter Annotation");
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}
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@Override
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public void destroy() {
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}
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}
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```
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```java
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/**
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* @author : heibaiying
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* @description :自定义监听器
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*/
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@WebListener
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public class CustomListenAnnotation implements ServletContextListener {
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//Web 应用程序初始化过程正在启动的通知
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@Override
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public void contextInitialized(ServletContextEvent sce) {
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System.out.println("容器初始化启动 Annotation");
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}
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/* 通知 servlet 上下文即将关闭
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* 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
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*/
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@Override
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public void contextDestroyed(ServletContextEvent sce) {
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System.out.println("容器即将销毁 Annotation");
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}
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}
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```
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```java
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/**
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* @author : heibaiying
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* @description : 自定义 servlet
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*/
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@WebServlet(urlPatterns = "/servletAnn")
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public class CustomServletAnnotation extends HttpServlet {
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@Override
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protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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resp.getWriter().append("CustomServlet Annotation");
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}
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@Override
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protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
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doGet(req, resp);
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}
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}
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```
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#### 3.2 使注解生效
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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；
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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）。
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