Java 类注册并初始化 DispatcherServlet

素颜马尾好姑娘i 2023-06-25 10:21 14阅读 0赞

> 今天听了一个教学视频，做一下记录，记录自己的理解.

## 官方文档 ##

*  [Web on Servlet Stack][]

## Java 类方式 ##

> Spring MVC项目，In a Servlet 3.0+ environment, 可以用 Java 类注册并初始化DispatcherServlet

public class MyWebApplicationInitializer implements WebApplicationInitializer { 
    
        @Override
        public void onStartup(ServletContext servletCxt) { 
    
            // Load Spring web application configuration
            AnnotationConfigWebApplicationContext ac = new AnnotationConfigWebApplicationContext();
            ac.register(AppConfig.class);
            ac.refresh();
    
            // Create and register the DispatcherServlet
            DispatcherServlet servlet = new DispatcherServlet(ac);
            ServletRegistration.Dynamic registration = servletCxt.addServlet("app", servlet);
            registration.setLoadOnStartup(1);
            registration.addMapping("/app/*");
        }
    }

### 执行流程 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RoZWJpZ2RpcHBlcmJkeA_size_16_color_FFFFFF_t_70]

## 传统方式 ##

> 传统xml方式

<web-app>
    
        <listener>
            <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
        </listener>
    
        <context-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/app-context.xml</param-value>
        </context-param>
    
        <servlet>
            <servlet-name>app</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <init-param>
                <param-name>contextConfigLocation</param-name>
                <param-value></param-value>
            </init-param>
            <load-on-startup>1</load-on-startup>
        </servlet>
    
        <servlet-mapping>
            <servlet-name>app</servlet-name>
            <url-pattern>/app/*</url-pattern> </servlet-mapping> </web-app>

## 延伸 ##

> 在做 Spring Boot 项目时，项目部署有两种方式，JAR部署、Tomcat 部署  
> JAR 部署，是因为 Spring Boot 有内置的Tomcat，所以能够启动成功，访问成功  
> 而项目代码打成WAR包进行Tomcat 部署部署，项目启动类需要继承 SpringBootServletInitializer 抽象类  
> SpringBootServletInitializer 实现了 WebApplicationInitializer ， 所以启动额外 Tomcat 容器的时候，会执行到 SpringBootServletInitializer 的 onStartup 方法，执行相关初始化工作 （原理同上）

@SpringBootApplication
    @EnableRedisHttpSession(maxInactiveIntervalInSeconds = 21600, redisNamespace = "fuzzy-search-web")
    public class FuzzySearchApplication extends SpringBootServletInitializer { 
    
        public static void main(String[] args){ 
            SpringApplication.run(FuzzySearchApplication.class, args);
        }
    
        @Override
        protected SpringApplicationBuilder configure(SpringApplicationBuilder builder){ 
            return builder.sources(FuzzySearchApplication.class);
        }
    
        @Bean
        public CookieHttpSessionStrategy cookieHttpSessionStrategy(){ 
            CookieHttpSessionStrategy strategy=new CookieHttpSessionStrategy();
            DefaultCookieSerializer cookieSerializer=new DefaultCookieSerializer();
            cookieSerializer.setCookieName("fuzzy-search-web");//cookies名称
            cookieSerializer.setCookieMaxAge(21600);//过期时间(秒)
            strategy.setCookieSerializer(cookieSerializer);
            return strategy;
        }
    
    
    }

[Web on Servlet Stack]: https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RoZWJpZ2RpcHBlcmJkeA_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191228124738212.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RoZWJpZ2RpcHBlcmJkeA==,size_16,color_FFFFFF,t_70