一、配置嵌入式Servlet容器
SpringBoot默认使用Tomcat作为嵌入式的Servlet容器;
1、定制和修改Servlet容器的相关配置
(1)、修改和server有关的配置(ServerProperties【也是EmbeddedServletContainerCustomizer】)。
server.port=8081
server.context-path=/crud
server.tomcat.uri-encoding=UTF-8
//通用的Servlet容器设置
server.xxx
//Tomcat的设置
server.tomcat.xxx
(2)、编写一个EmbeddedServletContainerCustomizer:嵌入式的Servlet容器的定制器;来修改Servlet容器的配置。
@Bean //一定要将这个定制器加入到容器中
public EmbeddedServletContainerCustomizer embeddedServletContainerCustomizer(){
return new EmbeddedServletContainerCustomizer() {
//定制嵌入式的Servlet容器相关的规则
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
container.setPort(8083);
}
}
}
2、注册Servlet三大组件【Servlet、Filter、Listener】
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。
注册三大组件的方式:
(1)、ServletRegistrationBean
public class MyServlet extends HttpServlet {
//处理get请求
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.getWriter().write("Hello MyServlet");
}
}
//注册三大组件
@Bean
public ServletRegistrationBean myServlet(){
ServletRegistrationBean registrationBean = new ServletRegistrationBean(new MyServlet(),"/myServlet");
return registrationBean;
}
(2)、FilterRegistrationBean
public class MyFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
System.out.println("MyFilter process...");
chain.doFilter(request,response);
}
@Override
public void destroy() {
}
}
@Bean
public FilterRegistrationBean myFilter(){
FilterRegistrationBean registrationBean = new FilterRegistrationBean();
registrationBean.setFilter(new MyFilter());
registrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));
return registrationBean;
}
(3)、ServletListenerRegistrationBean
public class MyListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println("contextInitialized...web应用启动");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
System.out.println("contextDestroyed...当前web项目销毁");
}
}
@Bean
public ServletListenerRegistrationBean myListener(){
ServletListenerRegistrationBean<MyListener> registrationBean = new ServletListenerRegistrationBean<>(new MyListener());
return registrationBean;
}
SpringBoot 整合 SpringMVC 的时候,自动的注册了 SpringMVC 的前端控制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());
//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;
}
二、配置其他嵌入式Servlet容器
默认支持:
1、Tomcat(默认使用):
<!-- 引入web模块默认就是使用嵌入式的Tomcat作为Servlet容器 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
2、Jetty(长连接):
<!-- 引入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>
<!-- 引入其他的Servlet容器 -->
<dependency>
<artifactId>spring-boot-starter-jetty</artifactId>
<groupId>org.springframework.boot</groupId>
</dependency>
3、Undertow(不支持JSP):
<!-- 引入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>
<!-- 引入其他的Servlet容器 -->
<dependency>
<artifactId>spring-boot-starter-undertow</artifactId>
<groupId>org.springframework.boot</groupId>
</dependency>
三、嵌入式Servlet容器自动配置原理
EmbeddedServletContainerAutoConfiguration:嵌入式的Servlet容器自动配置。
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@Import(BeanPostProcessorsRegistrar.class)
//导入BeanPostProcessorsRegistrar:Spring注解版;给容器中导入一些组件
//导入了EmbeddedServletContainerCustomizerBeanPostProcessor:
//后置处理器:bean初始化前后(创建完对象,还没赋值赋值)执行初始化工作
public class EmbeddedServletContainerAutoConfiguration {
@Configuration
@ConditionalOnClass({ Servlet.class, Tomcat.class }) //判断当前是否引入了Tomcat依赖;
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT) //判断当前容器没有用户自己定义EmbeddedServletContainerFactory:嵌入式的Servlet容器工厂;作用:创建嵌入式的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容器工厂)
public interface EmbeddedServletContainerFactory {
//获取嵌入式的Servlet容器
EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers);
}
2、EmbeddedServletContainer:(嵌入式的Servlet容器)
3、以 TomcatEmbeddedServletContainerFactory 为例
@Override
public EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers) {
//创建一个Tomcat
Tomcat tomcat = new Tomcat();
//配置Tomcat的基本环节
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);
//将配置好的Tomcat传入进去,返回一个EmbeddedServletContainer;并且启动Tomcat服务器
return getTomcatEmbeddedServletContainer(tomcat);
}
4、嵌入式容器的配置修改生效原理
ServerProperties、EmbeddedServletContainerCustomizer
EmbeddedServletContainerCustomizer:定制器帮我们修改了Servlet容器的配置。ServerProperties也是定制器。
5、容器中导入了 EmbeddedServletContainerCustomizerBeanPostProcessor
//初始化之前
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName)
throws BeansException {
//如果当前初始化的是一个ConfigurableEmbeddedServletContainer类型的组件
if (bean instanceof ConfigurableEmbeddedServletContainer) {
//
postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
}
return bean;
}
private void postProcessBeforeInitialization(
ConfigurableEmbeddedServletContainer bean) {
//获取所有的定制器,调用每一个定制器的customize方法来给Servlet容器进行属性赋值;
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
//从容器中获取所有这葛类型的组件:EmbeddedServletContainerCustomizer
//定制Servlet容器,给容器中可以添加一个EmbeddedServletContainerCustomizer类型的组件
.getBeansOfType(EmbeddedServletContainerCustomizer.class,
false, false)
.values());
Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
this.customizers = Collections.unmodifiableList(this.customizers);
}
return this.customizers;
}
步骤:
1、SpringBoot根据导入的依赖情况,给容器中添加相应的EmbeddedServletContainerFactory【TomcatEmbeddedServletContainerFactory】
2、容器中某个组件要创建对象就会惊动后置处理器;只要是嵌入式的Servlet容器工厂,后置处理器就工作;EmbeddedServletContainerCustomizerBeanPostProcessor;
3、后置处理器,从容器中获取所有的 EmbeddedServletContainerCustomizer,调用定制器的定制方法。
四、嵌入式Servlet容器启动原理
获取嵌入式的Servlet容器工厂:
1、SpringBoot应用启动运行run方法。
2、refreshContext(context);SpringBoot刷新IOC容器【创建IOC容器对象,并初始化容器,创建容器中的每一个组件】;如果是web应用创建 AnnotationConfigEmbeddedWebApplicationContext,否则:AnnotationConfigApplicationContext
3、refresh(context);刷新刚才创建好的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容器重写了onRefresh方法。
5、webioc容器会创建嵌入式的Servlet容器;createEmbeddedServletContainer()。
6、获取嵌入式的Servlet容器工厂:
EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory()
从ioc容器中获取EmbeddedServletContainerFactory 组件;TomcatEmbeddedServletContainerFactory 创建对象,后置处理器一看是这个对象,就获取所有的定制器来先定制Servlet容器的相关配置。
7、使用容器工厂获取嵌入式的Servlet容器:
this.embeddedServletContainer = containerFactory.getEmbeddedServletContainer(getSelfInitializer())
8、嵌入式的Servlet容器创建对象并启动Servlet容器。
先启动嵌入式的Servlet容器,再将ioc容器中剩下没有创建出的对象获取出来;IOC容器启动创建嵌入式的Servlet容器。
五、使用外部的Servlet容器
嵌入式Servlet容器:应用打成可执行的jar。优点:简单、便携;缺点:默认不支持JSP、优化定制比较复杂(使用定制器【ServerProperties、自定义EmbeddedServletContainerCustomizer】,自己编写嵌入式Servlet容器的创建工厂【EmbeddedServletContainerFactory】)。
外置的Servlet容器:外面安装Tomcat,然后将应用以war包的方式打包。
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 的子类,并调用configure方法。
public class ServletInitializer extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
//传入SpringBoot应用的主程序
return application.sources(SpringBoot04WebJspApplication.class);
}
}
4、启动服务器就可以使用。
六、外部的Servlet容器启动原理
jar包:执行SpringBoot主类的main方法,启动ioc容器,创建嵌入式的Servlet容器;
war包:启动服务器,服务器启动SpringBoot应用【SpringBootServletInitializer】,启动ioc容器;
servlet3.0规则:
1、服务器启动(web应用启动)会创建当前web应用里面每一个jar包里面 ServletContainerInitializer 实例。
2、ServletContainerInitializer 的实现放在jar包的META-INF/services
文件夹下,有一个名为javax.servlet.ServletContainerInitializer
的文件,内容就是 ServletContainerInitializer 的实现类的全类名。
3、可以使用 @HandlesTypes,在应用启动的时候加载我们感兴趣的类。
流程:
1、启动Tomcat。
2、org\springframework\spring-web\4.3.14.RELEASE\spring-web-4.3.14.RELEASE.jar!\META-INF\services\javax.servlet.ServletContainerInitializer:
Spring的web模块里面有这个文件:org.springframework.web.SpringServletContainerInitializer
3、SpringServletContainerInitializer 将 @HandlesTypes(WebApplicationInitializer.class) 标注的所有这个类型的类都传入到onStartup方法的Set<Class<?>>;为这些WebApplicationInitializer类型的类创建实例。
4、每一个 WebApplicationInitializer 都调用自己的 onStartup。
5、相当于我们的 SpringBootServletInitializer 的类会被创建对象,并执行onStartup方法。
6、SpringBootServletInitializer 实例执行onStartup的时候会createRootApplicationContext:创建容器。
protected WebApplicationContext createRootApplicationContext(
ServletContext servletContext) {
//1、创建SpringApplicationBuilder
SpringApplicationBuilder builder = createSpringApplicationBuilder();
StandardServletEnvironment environment = new StandardServletEnvironment();
environment.initPropertySources(servletContext, null);
builder.environment(environment);
builder.main(getClass());
ApplicationContext parent = getExistingRootWebApplicationContext(servletContext);
if (parent != null) {
this.logger.info("Root context already created (using as parent).");
servletContext.setAttribute(
WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, null);
builder.initializers(new ParentContextApplicationContextInitializer(parent));
}
builder.initializers(
new ServletContextApplicationContextInitializer(servletContext));
builder.contextClass(AnnotationConfigEmbeddedWebApplicationContext.class);
//调用configure方法,子类重写了这个方法,将SpringBoot的主程序类传入了进来
builder = configure(builder);
//使用builder创建一个Spring应用
SpringApplication application = builder.build();
if (application.getSources().isEmpty() && AnnotationUtils
.findAnnotation(getClass(), Configuration.class) != null) {
application.getSources().add(getClass());
}
Assert.state(!application.getSources().isEmpty(),
"No SpringApplication sources have been defined. Either override the "
+ "configure method or add an @Configuration annotation");
// Ensure error pages are registered
if (this.registerErrorPageFilter) {
application.getSources().add(ErrorPageFilterConfiguration.class);
}
//启动Spring应用
return run(application);
}
7、Spring的应用就启动并且创建IOC容器。
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
FailureAnalyzers analyzers = null;
configureHeadlessProperty();
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
analyzers = new FailureAnalyzers(context);
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
//刷新IOC容器
refreshContext(context);
afterRefresh(context, applicationArguments);
listeners.finished(context, null);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
return context;
}
catch (Throwable ex) {
handleRunFailure(context, listeners, analyzers, ex);
throw new IllegalStateException(ex);
}
}
启动Servlet容器,再启动SpringBoot应用。