SpringBoot中的嵌入式Servlet

在SpringBoot中，有一個默認的嵌入式Servlet容器——Tomcat容器

1、如何定製和修改Servlet容器的有關配置？

【1】在SpringBoot的配置文件中進行配置

# 修改服務器的端口號
server.port=8090
# 修改訪問路徑
server.servlet.context-path=/webDemo
# 設置Tomcat容器的字符編碼
server.tomcat.uri-encoding=UTF-8

# server.tomcat.xxx=  是對tomcat容器的設置
# server.xxx.xxx= 是通用的servlet容器設置

【2】手動編寫一個嵌入式的Servlet容器的定製器

① 1.x版本：使用EmbeddedServletContainerCustomizer來修改Servlet容器的配置

@Configuration
public class MyMvcConfiguration extends WebMvcConfigurerAdapter {

     //在容器中配置嵌入式Servlet容器
      @Bean
      public EmbeddedServletContainerCustomizer embeddedServletContainerCustomizer(){
          return new EmbeddedServletContainerCustomizer(){

              @Override
              public void customize(ConfigurableEmbeddedServletContainer container) {
                  container.setPort(8888);
              }
          };
      }
}

② 2.x版本：使用ConfigurableServletWebServerFactory來修改Servlet容器的配置

@Bean
    public ConfigurableServletWebServerFactory configurableServletWebServerFactory(){
        TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory();
        factory.setPort(8010);
        return factory;
    }

2、在SpringBoot中註冊三大組件(Servlet、Filter、Listener)

【1】1.x版本

① 註冊Servlet

在容器中註冊自定義的Servlet：

@Configuration
public class MyServerConfiguration{
      @Bean
      public ServletRegistrationBean myServlet(){
          ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new MyServlet(),"/myServlet");
          return servletRegistrationBean;
      }
}

自定義的Servlet：

public class MyServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        PrintWriter out = resp.getWriter();
        out.write("Hello,MyServlet");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }
}

【2】註冊過濾器Filter

在容器中註冊自定義的過濾器：

@Configuration
public class MyServerConfiguration {
     /*註冊過濾器Filter組件*/
     @Bean
      public FilterRegistrationBean myFilter(){
          FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
          filterRegistrationBean.setFilter(new MyFilter());
          filterRegistrationBean.setUrlPatterns(Arrays.asList("/myServlet","/hello"));
          return filterRegistrationBean;
      }
}

自定義的過濾器：

public class MyFilter implements Filter {
    /* *
     * @description //TODO  過濾器的初始化方法
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    
    /* 
     * @description //TODO 過濾器的執行方法
     */
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("MyFiler is processing……");
        chain.doFilter(servletRequest,servletResponse);
    }
  /* 過濾器的銷燬方法*/
    @Override
    public void destroy() {

    }
}

【3】註冊監聽器(Listener)

在容器中註冊監聽器：

  @Bean
      public ServletListenerRegistrationBean myServletListener(){
          ServletListenerRegistrationBean<MyServletListener> servletRegistrationBean = new ServletListenerRegistrationBean<MyServletListener>(new MyServletListener());
          return servletRegistrationBean;
      }

自定義的監聽器：

public class MyServletListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("web應用啓動……");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("web容器銷燬……");
    }
}

可以註冊的監聽器：

static {
        Set<Class<?>> types = new HashSet();
        types.add(ServletContextAttributeListener.class);
        types.add(ServletRequestListener.class);
        types.add(ServletRequestAttributeListener.class);
        types.add(HttpSessionAttributeListener.class);
        types.add(HttpSessionListener.class);
        types.add(ServletContextListener.class);
        SUPPORTED_TYPES = Collections.unmodifiableSet(types);
    }

SpringBoot會幫助我們自動註冊Spring MVC的前端控制器 (DispatcherServlet)

  默認攔截(/)：除jsp請求外，攔截所有的請求，包括靜態資源；(/*)：會攔截jsp請求。
  可以通過server.servletPath來修改SpringMVC前端控制器默認攔截的請求路徑。

@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public ServletRegistrationBean dispatcherServletRegistration(
	DispatcherServlet dispatcherServlet) {
	ServletRegistrationBean registration = new ServletRegistrationBean(
	dispatcherServlet, this.serverProperties.getServletMapping());
	registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
	registration.setLoadOnStartup(
	this.webMvcProperties.getServlet().getLoadOnStartup());
	if (this.multipartConfig != null) {
		registration.setMultipartConfig(this.multipartConfig);
	}
	return registration;
}

【2】2.x版本註冊方式與上面的相同。

3、使用其他Servlet容器

  在SpringBoot中，默認使用Tomcat服務器，但是也可以切換成·Undertow和Jetty。

如何切換其他容器？

【1】先排除SpringBoot的默認容器Tomcat

 <!--導入web模塊-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                    <groupId>org.springframework.boot</groupId>
                </exclusion>
            </exclusions>
        </dependency>

【2】引入目標容器的依賴

① 切換成undertow容器：

 <!--切換其他容器
   1、先排除默認的tomcat容器
   2、引入要切換的容器的座標
-->
 <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-undertow -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-undertow</artifactId>
<!--<version>SpringBoot的版本號</version> -->
</dependency>

② 切換成Netty容器

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jetty</artifactId>
    <version>版本號</version>
</dependency>