SpringBoot04-servlet

配置嵌入式Servlet容器

1. Servlet默认使用Tomcat作为嵌入式的Servlet容器
   • 
2. 如何定制和修改Servlet容器的相关配置?
   1. 修改和Server有关的配置(ServerProperties, 其实也是一个WebServerFactoryCustomizer) 

      server.port=8081
      server.context-path=/xxx
      
      server.tomcat.uri-encoding=UTF-8
      
      //通用的Servlet容器设置
      server.xxx
      
      //Tomcat的设置
      server.tomcat.xxx

   2. 编写一个WebServerFactoryCustomizer<ConfigurableWebServerFactory>: 嵌入式的Servlet容器的定制器, 来修改Servlet容器的配置, (比起1, 优先级更高)

          @Bean
          public WebServerFactoryCustomizer<ConfigurableWebServerFactory> webServerFactoryCustomizer(){
              return new WebServerFactoryCustomizer<ConfigurableWebServerFactory>() {
                  //定制嵌入式的Servlet容器相关的规则
                  @Override
                  public void customize(ConfigurableWebServerFactory factory) {
                      factory.setPort(8081);
                  }
              };
          }

3. 注册Servlet, Filter, Listener三大组件.
   1. 由于SpringBoot默认是以jar包的方式启动嵌入式的Servlet容器来启动SpringBoot的web应用, 没有web.xml文件, 所以注册三大组件用以下方式.
   2. ServletRegistrationBean

      @Configuration
      public class MyServerConfig {
      
          //注册三大组件
          @Bean
          public ServletRegistrationBean myServlet() {
      
              ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new MyServlet(), "/myServlet");
              servletRegistrationBean.setLoadOnStartup(1);
              return servletRegistrationBean;
          }
      }

   3. FilterRegistrationBean

          @Bean
          public FilterRegistrationBean myFilter() {
              FilterRegistrationBean registrationBean = new FilterRegistrationBean();
              registrationBean.setFilter(new MyFilter());
              registrationBean.setUrlPatterns(Arrays.asList("/hello", "/myServlet"));
              return registrationBean;
          }

   4. ServletListenerRegistrationBean

          @Bean
          public ServletListenerRegistrationBean myListener() {
              ServletListenerRegistrationBean<MyListener> registrationBean = new ServletListenerRegistrationBean<>(new MyListener());
              return registrationBean;
          }

   5. 举个例子: SpringBoot再帮我们自动配置SpringMVC时, 自动注册前端控制器DispatcherServlet, 其中DispatcherServletAutoConfiguration

      @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());
      
          //默认拦截： /  所有请求；包静态资源，但是不拦截jsp请求；   /*会拦截jsp
          //可以通过server.servletPath来修改SpringMVC前端控制器默认拦截的请求路径
          
         registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
         registration.setLoadOnStartup(
               this.webMvcProperties.getServlet().getLoadOnStartup());
         if (this.multipartConfig != null) {
            registration.setMultipartConfig(this.multipartConfig);
         }
         return registration;
      }

4. 使用其他的Servlet容器
   1. Tomcat(默认使用), 先排除掉

              <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. Undertow(不支持Jsp, 但并发处理能力很好).

      <dependency>
         <artifactId>spring-boot-starter-undertow</artifactId>
         <groupId>org.springframework.boot</groupId>
      </dependency>

   3. Jetty(长连接)

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

使用外置的Servlet容器

1. 嵌入式Servlet容器: 打jar包
   1. 优点: 简单便捷.
   2. 缺点: 默认不支持Jsp, 优化定制Servlet容器很复杂(定制器, 自己编写嵌入式Servlet容器的创建工厂).
2. 外置的Servlet容器: 外面安装Tomcat, 应用war包的方式打包.
3. 步骤
   1. 必须创建一个war项目: 利用idea创建好目录结构
   2. 将嵌入式的Tomcat指定为provided

      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-tomcat</artifactId>
         <scope>provided</scope>
      </dependency>

   3. 必须编写一个SpringBootServletInitializer, 并且调用configure方法

      public class ServletInitializer extends SpringBootServletInitializer {
      
          @Override
          protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
              return application.sources(SpringBoot04WebWarApplication.class);
          }
      }

   4. 启动服务器