SpringBoot中的嵌入式Servlet

在SpringBoot中，有一个默认的嵌入式Servlet容器——Tomcat容器

1、如何定制和修改Servlet容器的有关配置？

【1】在SpringBoot的配置文件中进行配置

# 修改服务器的端口号
server.port=8090
# 修改访问路径
server.servlet.context-path=/webDemo
# 设置Tomcat容器的字符编码
server.tomcat.uri-encoding=UTF-8

# server.tomcat.xxx=  是对tomcat容器的设置
# server.xxx.xxx= 是通用的servlet容器设置

【2】手动编写一个嵌入式的Servlet容器的定制器

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

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

2、在SpringBoot中注册三大组件(Servlet、Filter、Listener)

【1】1.x版本

① 注册Servlet

在容器中注册自定义的Servlet：

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

自定义的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】注册过滤器Filter

在容器中注册自定义的过滤器：

@Configuration
public class MyServerConfiguration {
     /*注册过滤器Filter组件*/
     @Bean
      public FilterRegistrationBean myFilter(){
          FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
          filterRegistrationBean.setFilter(new MyFilter());
          filterRegistrationBean.setUrlPatterns(Arrays.asList("/myServlet","/hello"));
          return filterRegistrationBean;
      }
}

自定义的过滤器：

public class MyFilter implements Filter {
    /* *
     * @description //TODO  过滤器的初始化方法
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    
    /* 
     * @description //TODO 过滤器的执行方法
     */
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("MyFiler is processing……");
        chain.doFilter(servletRequest,servletResponse);
    }
  /* 过滤器的销毁方法*/
    @Override
    public void destroy() {

    }
}

【3】注册监听器(Listener)

在容器中注册监听器：

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

自定义的监听器：

public class MyServletListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("web应用启动……");
    }

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

可以注册的监听器：

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会帮助我们自动注册Spring MVC的前端控制器 (DispatcherServlet)

  默认拦截(/)：除jsp请求外，拦截所有的请求，包括静态资源；(/*)：会拦截jsp请求。
  可以通过server.servletPath来修改SpringMVC前端控制器默认拦截的请求路径。

@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版本注册方式与上面的相同。

3、使用其他Servlet容器

  在SpringBoot中，默认使用Tomcat服务器，但是也可以切换成·Undertow和Jetty。

如何切换其他容器？

【1】先排除SpringBoot的默认容器Tomcat

 <!--导入web模块-->
        <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】引入目标容器的依赖

① 切换成undertow容器：

 <!--切换其他容器
   1、先排除默认的tomcat容器
   2、引入要切换的容器的座标
-->
 <!-- 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的版本号</version> -->
</dependency>

② 切换成Netty容器

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