Spring Boot 內建與外接Servlet容器講解(六)
1、配置嵌入式Servlet容器
SpringBoot預設使用Tomcat作為嵌入式的Servlet容器;
問題?
1)、如何定製和修改Servlet容器的相關配置;
1、修改和server有關的配置(ServerProperties【也是EmbeddedServletContainerCustomizer】);
server.port=8081
server.context-path=/crud
server.tomcat.uri-encoding=UTF-8
//通用的Servlet容器設定
server.xxx
//Tomcat的設定
server.tomcat.xxx
2、編寫一個EmbeddedServletContainerCustomizer
@Bean //一定要將這個定製器加入到容器中
public EmbeddedServletContainerCustomizer embeddedServletContainerCustomizer(){
return new EmbeddedServletContainerCustomizer() {
//定製嵌入式的Servlet容器相關的規則
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
container.setPort(8083);
}
};
}
2)、註冊Servlet三大元件【Servlet、Filter、Listener】
由於SpringBoot預設是以jar包的方式啟動嵌入式的Servlet容器來啟動SpringBoot的web應用,沒有web.xml檔案。
註冊三大元件用以下方式
ServletRegistrationBean
//註冊三大元件
@Bean
public ServletRegistrationBean myServlet(){
ServletRegistrationBean registrationBean = new ServletRegistrationBean(new MyServlet(),"/myServlet");
return registrationBean;
}
FilterRegistrationBean
@Bean
public FilterRegistrationBean myFilter(){
FilterRegistrationBean registrationBean = new FilterRegistrationBean();
registrationBean.setFilter(new MyFilter());
registrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));
return registrationBean;
}
ServletListenerRegistrationBean
@Bean
public ServletListenerRegistrationBean myListener(){
ServletListenerRegistrationBean<MyListener> registrationBean = new ServletListenerRegistrationBean<>(new MyListener());
return registrationBean;
}
SpringBoot幫我們自動SpringMVC的時候,自動的註冊SpringMVC的前端控制器;DIspatcherServlet;
DispatcherServletAutoConfiguration中:
@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());
//預設攔截: / 所有請求;包靜態資源,但是不攔截jsp請求; /*會攔截jsp
//可以通過server.servletPath來修改SpringMVC前端控制器預設攔截的請求路徑
registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
registration.setLoadOnStartup(
this.webMvcProperties.getServlet().getLoadOnStartup());
if (this.multipartConfig != null) {
registration.setMultipartConfig(this.multipartConfig);
}
return registration;
}
2)、SpringBoot能不能支援其他的Servlet容器;
3)、替換為其他嵌入式Servlet容器
預設支援:
Tomcat(預設使用)
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
引入web模組預設就是使用嵌入式的Tomcat作為Servlet容器;
</dependency>
Jetty
<!-- 引入web模組 -->
<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>
<!--引入其他的Servlet容器-->
<dependency>
<artifactId>spring-boot-starter-jetty</artifactId>
<groupId>org.springframework.boot</groupId>
</dependency>
Undertow
<!-- 引入web模組 -->
<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>
<!--引入其他的Servlet容器-->
<dependency>
<artifactId>spring-boot-starter-undertow</artifactId>
<groupId>org.springframework.boot</groupId>
</dependency>
4)、嵌入式Servlet容器自動配置原理;
EmbeddedServletContainerAutoConfiguration:嵌入式的Servlet容器自動配置?
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@Import(BeanPostProcessorsRegistrar.class)
//匯入BeanPostProcessorsRegistrar:Spring註解版;給容器中匯入一些元件
//匯入了EmbeddedServletContainerCustomizerBeanPostProcessor:
//後置處理器:bean初始化前後(建立完物件,還沒賦值賦值)執行初始化工作
public class EmbeddedServletContainerAutoConfiguration {
@Configuration
@ConditionalOnClass({ Servlet.class, Tomcat.class })//判斷當前是否引入了Tomcat依賴;
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)//判斷當前容器沒有使用者自己定義EmbeddedServletContainerFactory:嵌入式的Servlet容器工廠;作用:建立嵌入式的Servlet容器
public static class EmbeddedTomcat {
@Bean
public TomcatEmbeddedServletContainerFactory tomcatEmbeddedServletContainerFactory() {
return new TomcatEmbeddedServletContainerFactory();
}
}
/**
* Nested configuration if Jetty is being used.
*/
@Configuration
@ConditionalOnClass({ Servlet.class, Server.class, Loader.class,
WebAppContext.class })
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
public static class EmbeddedJetty {
@Bean
public JettyEmbeddedServletContainerFactory jettyEmbeddedServletContainerFactory() {
return new JettyEmbeddedServletContainerFactory();
}
}
/**
* Nested configuration if Undertow is being used.
*/
@Configuration
@ConditionalOnClass({ Servlet.class, Undertow.class, SslClientAuthMode.class })
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
public static class EmbeddedUndertow {
@Bean
public UndertowEmbeddedServletContainerFactory undertowEmbeddedServletContainerFactory() {
return new UndertowEmbeddedServletContainerFactory();
}
}
1)、EmbeddedServletContainerFactory(嵌入式Servlet容器工廠)
public interface EmbeddedServletContainerFactory {
//獲取嵌入式的Servlet容器
EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers);
}
2)、EmbeddedServletContainer:(嵌入式的Servlet容器)
3)、以TomcatEmbeddedServletContainerFactory為例
@Override
public EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers) {
//建立一個Tomcat
Tomcat tomcat = new Tomcat();
//配置Tomcat的基本環節
File baseDir = (this.baseDirectory != null ? this.baseDirectory
: createTempDir("tomcat"));
tomcat.setBaseDir(baseDir.getAbsolutePath());
Connector connector = new Connector(this.protocol);
tomcat.getService().addConnector(connector);
customizeConnector(connector);
tomcat.setConnector(connector);
tomcat.getHost().setAutoDeploy(false);
configureEngine(tomcat.getEngine());
for (Connector additionalConnector : this.additionalTomcatConnectors) {
tomcat.getService().addConnector(additionalConnector);
}
prepareContext(tomcat.getHost(), initializers);
//將配置好的Tomcat傳入進去,返回一個EmbeddedServletContainer;並且啟動Tomcat伺服器
return getTomcatEmbeddedServletContainer(tomcat);
}
4)、我們對嵌入式容器的配置修改是怎麼生效?
ServerProperties、EmbeddedServletContainerCustomizer
EmbeddedServletContainerCustomizer:定製器幫我們修改了Servlet容器的配置?
怎麼修改的原理?
5)、容器中匯入了EmbeddedServletContainerCustomizerBeanPostProcessor
//大概在33行
//初始化之前
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName)
throws BeansException {
//如果當前初始化的是一個ConfigurableEmbeddedServletContainer型別的元件
if (bean instanceof ConfigurableEmbeddedServletContainer) {
//
postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
}
return bean;
}
private void postProcessBeforeInitialization(
ConfigurableEmbeddedServletContainer bean) {
//獲取所有的定製器,呼叫每一個定製器的customize方法來給Servlet容器進行屬性賦值;
for (EmbeddedServletContainerCustomizer customizer : getCustomizers()) {
customizer.customize(bean);
}
}
private Collection<EmbeddedServletContainerCustomizer> getCustomizers() {
if (this.customizers == null) {
// Look up does not include the parent context
this.customizers = new ArrayList<EmbeddedServletContainerCustomizer>(
this.beanFactory
//從容器中獲取所有這葛型別的元件:EmbeddedServletContainerCustomizer
//定製Servlet容器,給容器中可以新增一個EmbeddedServletContainerCustomizer型別的元件
.getBeansOfType(EmbeddedServletContainerCustomizer.class,
false, false)
.values());
Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
this.customizers = Collections.unmodifiableList(this.customizers);
}
return this.customizers;
}
ServerProperties也是定製器
步驟:
1)、SpringBoot根據匯入的依賴情況,給容器中新增相應的EmbeddedServletContainerFactory【TomcatEmbeddedServletContainerFactory】
2)、容器中某個元件要建立物件就會驚動後置處理器;EmbeddedServletContainerCustomizerBeanPostProcessor;
只要是嵌入式的Servlet容器工廠,後置處理器就工作;
3)、後置處理器,從容器中獲取所有的EmbeddedServletContainerCustomizer,呼叫定製器的定製方法
5)、嵌入式Servlet容器啟動原理;
什麼時候建立嵌入式的Servlet容器工廠?什麼時候獲取嵌入式的Servlet容器並啟動Tomcat;
獲取嵌入式的Servlet容器工廠:
1)、SpringBoot應用啟動執行run方法
2)、refreshContext(context);SpringBoot重新整理IOC容器【建立IOC容器物件,並初始化容器,建立容器中的每一個元件】;如果是web應用建立AnnotationConfigEmbeddedWebApplicationContext,否則:AnnotationConfigApplicationContext
3)、refresh(context);重新整理剛才建立好的ioc容器;
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
// 。。。。。
onRefresh();
// Check for listener beans and register them.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
finishRefresh();
}
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// Destroy already created singletons to avoid dangling resources.
destroyBeans();
// Reset 'active' flag.
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
}
finally {
// Reset common introspection caches in Spring's core, since we
// might not ever need metadata for singleton beans anymore...
resetCommonCaches();
}
}
}
4)、 onRefresh(); web的ioc容器重寫了onRefresh方法
5)、web ioc容器會建立嵌入式的Servlet容器;createEmbeddedServletContainer();
6)、獲取嵌入式的Servlet容器工廠:
EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();
從ioc容器中獲取EmbeddedServletContainerFactory 元件;TomcatEmbeddedServletContainerFactory建立物件,後置處理器一看是這個物件,就獲取所有的定製器來先定製Servlet容器的相關配置;
7)、使用容器工廠獲取嵌入式的Servlet容器:this.embeddedServletContainer = containerFactory .getEmbeddedServletContainer(getSelfInitializer());
8)、嵌入式的Servlet容器建立物件並啟動Servlet容器;
先啟動嵌入式的Servlet容器,再將ioc容器中剩下沒有創建出的物件獲取出來;
IOC容器啟動建立嵌入式的Servlet容器
2、使用外接的Servlet容器
嵌入式Servlet容器:應用打成可執行的jar
優點:簡單、便攜;
缺點:預設不支援JSP、優化定製比較複雜(使用定製器【ServerProperties、自定義EmbeddedServletContainerCustomizer】,自己編寫嵌入式Servlet容器的建立工廠【EmbeddedServletContainerFactory】);
外接的Servlet容器:外面安裝Tomcat—應用war包的方式打包;
步驟
1)、必須建立一個war專案;(利用idea建立好目錄結構)
2)、將嵌入式的Tomcat指定為provided;
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
3)、必須編寫一個SpringBootServletInitializer的子類,並呼叫configure方法
public class ServletInitializer extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
//傳入SpringBoot應用的主程式
return application.sources(SpringBoot04WebJspApplication.class);
}
}
如果你建立的SpringBoot的war專案這個子類會自動幫我們建立好。
4)、啟動伺服器就可以使用(在專案配置一下本地Tomcat啟動即可);
總結:
jar包:執行SpringBoot主類的main方法,啟動ioc容器,建立嵌入式的Servlet容器;
war包:啟動伺服器,伺服器啟動SpringBoot應用【SpringBootServletInitializer】,啟動ioc容器;