vue 依赖注入，Springboot2Web原生组件注入

2023-09-28 阅读 33 评论 0

摘要：官方文档 - Servlets, Filters, and listeners 使用原生的注解Servlet API @ServletComponentScan(basePackages = “com.atguigu.admin”) :指定原生Servlet组件都放在那里 @WebServlet(urlPatterns = “/my”):效果:直接响应,没有经过Spring的拦截器? @

官方文档 - Servlets, Filters, and listeners

使用原生的注解Servlet API

@ServletComponentScan(basePackages = “com.atguigu.admin”) :指定原生Servlet组件都放在那里
@WebServlet(urlPatterns = “/my”):效果:直接响应,没有经过Spring的拦截器?
@WebFilter(urlPatterns ={"/css/","/images/"})
@WebListener

MyServlet 类

@WebServlet(urlPatterns = "/my")
public class MyServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {resp.getWriter().write("6666");}
}

主配置类

//可以将自己写的servlet扫描进来
@ServletComponentScan(basePackages = "com.yujie")
@SpringBootApplication
public class Boot05WebAdminApplication {public static void main(String[] args) {SpringApplication.run(Boot05WebAdminApplication.class, args);}
}

在这里插入图片描述
过滤器

@Slf4j
//拦截css下的所有内容
//注意：*是servlet写法，**是spring写法
@WebFilter(urlPatterns ={"/css/*","/images/*"})
public class MyFilter implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {log.info("MyFilter初始化完成");}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {log.info("MyFilter工作");filterChain.doFilter(servletRequest,servletResponse);}@Overridepublic void destroy() {log.info("MyFilter销毁");}
}

vue 依赖注入，在这里插入图片描述
监听器

@Slf4j
@WebListener
public class MyServletContextListener implements ServletContextListener {@Overridepublic void contextInitialized(ServletContextEvent sce) {log.info("监听到项目初始化");}@Overridepublic void contextDestroyed(ServletContextEvent sce) {log.info("监听到项目销毁");}
}

Spring方式注入使用RegistrationBean

ServletRegistrationBean, FilterRegistrationBean, and ServletListenerRegistrationBean
可以注解掉前面的3个注解，让后使用RegistrationBean来注册。

@Configuration
public class MyRegistConfig {@Beanpublic ServletRegistrationBean myServlet(){MyServlet myServlet = new MyServlet();return new ServletRegistrationBean(myServlet,"/my","/my02");}@Beanpublic FilterRegistrationBean myFilter(){MyFilter myFilter = new MyFilter();
//        return new FilterRegistrationBean(myFilter,myServlet());FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(myFilter);filterRegistrationBean.setUrlPatterns(Arrays.asList("/my","/css/*"));return filterRegistrationBean;}@Beanpublic ServletListenerRegistrationBean myListener(){MyServletContextListener mySwervletContextListener = new MyServletContextListener();return new ServletListenerRegistrationBean(mySwervletContextListener);}
}

细节:

@Configuration(proxyBeanMethods=false)
public class MyRegistConfig {

这里没有写proxyBeanMethods=false。如果写了说明当前类每次一调用类里面的方法，servlet都会新建一次。比如我们调用MyFilter的时候，servlet就重新new了一下。(proxyBeanMethods=true)它可以保证依赖的组件始终是单实例的。

【源码分析】DispatcherServlet注入原理

为什么自己写的@WebServlet(urlPatterns = “/my”):不会经过spring的拦截器。

根据上面的分析，我们系统中有两个servlet，一个MyServlet，处理的路径是/my。DispatcherServlet处理的路径是/
我们可以分析它的注入原理

springboot接口框架？org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration配置类

@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass(DispatcherServlet.class)
@AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
public class DispatcherServletAutoConfiguration {/** The bean name for a DispatcherServlet that will be mapped to the root URL "/"*/public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";/** The bean name for a ServletRegistrationBean for the DispatcherServlet "/"*/public static final String DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME = "dispatcherServletRegistration";@Configuration(proxyBeanMethods = false)@Conditional(DefaultDispatcherServletCondition.class)@ConditionalOnClass(ServletRegistration.class)@EnableConfigurationProperties(WebMvcProperties.class)protected static class DispatcherServletConfiguration {//创建DispatcherServlet类的Bean@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)public DispatcherServlet dispatcherServlet(WebMvcProperties webMvcProperties) {DispatcherServlet dispatcherServlet = new DispatcherServlet();dispatcherServlet.setDispatchOptionsRequest(webMvcProperties.isDispatchOptionsRequest());dispatcherServlet.setDispatchTraceRequest(webMvcProperties.isDispatchTraceRequest());dispatcherServlet.setThrowExceptionIfNoHandlerFound(webMvcProperties.isThrowExceptionIfNoHandlerFound());dispatcherServlet.setPublishEvents(webMvcProperties.isPublishRequestHandledEvents());dispatcherServlet.setEnableLoggingRequestDetails(webMvcProperties.isLogRequestDetails());return dispatcherServlet;}@Bean@ConditionalOnBean(MultipartResolver.class)@ConditionalOnMissingBean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)public MultipartResolver multipartResolver(MultipartResolver resolver) {// Detect if the user has created a MultipartResolver but named it incorrectlyreturn resolver;}}@Configuration(proxyBeanMethods = false)@Conditional(DispatcherServletRegistrationCondition.class)@ConditionalOnClass(ServletRegistration.class)@EnableConfigurationProperties(WebMvcProperties.class)@Import(DispatcherServletConfiguration.class)protected static class DispatcherServletRegistrationConfiguration {//注册DispatcherServlet类@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)public DispatcherServletRegistrationBean dispatcherServletRegistration(DispatcherServlet dispatcherServlet,WebMvcProperties webMvcProperties, ObjectProvider<MultipartConfigElement> multipartConfig) {DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(dispatcherServlet,webMvcProperties.getServlet().getPath());registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);registration.setLoadOnStartup(webMvcProperties.getServlet().getLoadOnStartup());multipartConfig.ifAvailable(registration::setMultipartConfig);return registration;}}...}

扩展: DispatchServlet如何注册进来

容器中自动配置了DispatcherServlet 属性绑定到WebMvcProperties; 对应的配置文件配置项是
spring.mvc。
通过ServletRegistrationBean 把DispatcherServlet配置进来。
默认映射的是/路径。

在这里插入图片描述
Tomcat-Servlet;
多个Servlet都能处理到同一层路径, 精确优选原则
A: /my/
B: /my/1

上图中发送/my，按照精确优先原则，来到Tomcat处理。而只有我们触发spring流程，才会有拦截器的作用。所以上面我们自己写的servlet并没有被拦截。

嵌入式Servlet容器

1.切换嵌入式Servlet容器

默认支持的webServer

Tomcat, Jetty, or Undertow
ServletWebServerApplicationContext 容器启动寻找ServletwebServerFactory并引导创建服务器

springboot好用组件？切换服务器
在这里插入图片描述

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

原理

SpringBoot应用启动发现当前是Web应用。web场景包-导入tomcat

web应用会创建一个web版的ioc容器 ServletWebServerApplicationContext

ServletWebServerApplicationContext 启动的时候寻找ServletWebServerFactory
(Servlet的web服务器工厂—> Servlet 的web服务器)

SpringBoot底层默认有很多的WebServerI厂; TomCatServletWebServerFactory,lu.com
JettyServletWebServerFactory, or UndertowServletWebServerFactory

Springboot教程、底层直接会有一个自动配置类。ServletWebServerFactoryAutoConfiguration

ServletWebServerFactoryAutoConfiguration导入了ServletWebServerFactoryConfiguration
(配置类)

ServletWebServerFactoryConfiguration 配置类根据动态判断系统中到底导入了那个Web服务器
的包。(默认是web- starter导入tomcat包)，容器中就有TomcatServletWebServerFactory

TomcatServletWebServerFactory 创建出Tomcat服务器并启动; TomcatWebServer. 的构造器拥有
初始化方法initialize—this . tomcat. start();

内嵌服务器，就是手动把启动服务器的代码调用(tomcat 核心jar包存在)

2.定制Servlet容器

实现WebServerFactoryCustomizer

springboot核心功能，把配置文件的值和ServletWebServerFactory进行绑定

修改配置文件server.xxx

直接自定义ConfigurableServletWebServerFactory

xxxxxCustomizer:定制化器，可以改变xxx的默认规则

import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
import org.springframework.stereotype.Component;@Component
public class CustomizationBean implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {@Overridepublic void customize(ConfigurableServletWebServerFactory server) {server.setPort(9000);}}

定制化原理

1.定制化的常见方式

修改配置文件;
xxxxxCustomizer;
编写自定义的配置类xxxConfiguration; + @Bean替换、增加容器中默认组件;视图解析器
Web应用编写-个配置类实现WebMvcConfigurer即可定制化web功能; + @Bean给容器中再扩展一些组件

@Configuration
public class AdminWebConfig implements WebMvcConfigurer

@EnableWebMvc + WebMvcConfigurer一@Bean可以全面接管SpringMVC,所有规则全部自己重新
配置;实现定制和扩展功能

Springboot。原理
1、WebMvcAutoConfiguration 默认的SpringMVC的自动配置功能类。静态资源、欢迎页…
2、一旦使用@EnableWebMvC、。会@Import(DelegatingWebMvcConfiguration.class)
3、 DelegatingWebMvcConfiguration 的作用，只保证SpringMVC最基本的使用*