SpringBoot配置嵌入式Servlet容器

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#默认程序端口为8080
server.port=8080 
#用户会话session过期事件,以秒为单位
server.session.cookie.comment=60 
#配配置默认的访问路径,默认为/
server.context-path= /

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@ConfigurationProperties(prefix = "server", ignoreUnknownFields = true)
public class ServerProperties
		implements EmbeddedServletContainerCustomizer, EnvironmentAware, Ordered {
	private Integer port;

	private InetAddress address;

	private String contextPath;

	private String displayName = "application";

	@NestedConfigurationProperty
	private ErrorProperties error = new ErrorProperties();

	private String servletPath = "/";


	private final Map<String, String> contextParameters = new HashMap<String, String>();

	private Boolean useForwardHeaders;

	private String serverHeader;

	private int maxHttpHeaderSize = 0; // bytes

	private int maxHttpPostSize = 0; // bytes

	private Integer connectionTimeout;

	private Session session = new Session();

	@NestedConfigurationProperty
	private Ssl ssl;

	@NestedConfigurationProperty
	private Compression compression = new Compression();

	@NestedConfigurationProperty
	private JspServlet jspServlet;

	private final Tomcat tomcat = new Tomcat();

	private final Jetty jetty = new Jetty();

	private final Undertow undertow = new Undertow();

	private Environment environment;

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//配置嵌入式的Servlet容器
@Bean
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);
        }
    };
}

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package com.hph.springboot.config;

import com.hph.springboot.filter.MyFilter;
import com.hph.springboot.listener.MyListener;
import com.hph.springboot.servlet.MyServlet;
import org.springframework.boot.context.embedded.ConfigurableEmbeddedServletContainer;
import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizer;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Arrays;

@Configuration
public class MyServerConfig {

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

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

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


    //配置嵌入式的Servlet容器
    @Bean
    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);
            }
        };
    }

}

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	//这里的Servlet就是标准的Javax中的Servlet	
public ServletRegistrationBean(Servlet servlet, String... urlMappings) {
	this(servlet, true, urlMappings);
}

/**
 * Create a new {@link ServletRegistrationBean} instance with the specified
 * {@link Servlet} and URL mappings.
 * @param servlet the servlet being mapped
 * @param alwaysMapUrl if omitted URL mappings should be replaced with '/*'
 * @param urlMappings the URLs being mapped
 */
public ServletRegistrationBean(Servlet servlet, boolean alwaysMapUrl,
		String... urlMappings) {
	Assert.notNull(servlet, "Servlet must not be null");
	Assert.notNull(urlMappings, "UrlMappings must not be null");
	this.servlet = servlet;
	this.alwaysMapUrl = alwaysMapUrl;
	this.urlMappings.addAll(Arrays.asList(urlMappings));
}

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public FilterRegistrationBean() {
	}

	/**
	 * Create a new {@link FilterRegistrationBean} instance to be registered with the
	 * specified {@link ServletRegistrationBean}s.
	 * @param filter the filter to register
	 * @param servletRegistrationBeans associate {@link ServletRegistrationBean}s
	 */
	public FilterRegistrationBean(Filter filter,
			ServletRegistrationBean... servletRegistrationBeans) {
		super(servletRegistrationBeans);
		Assert.notNull(filter, "Filter must not be null");
		this.filter = filter;
	}

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package com.hph.springboot.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

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");
    }
}

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package com.hph.springboot.listener;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

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");
    }
}

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package com.hph.springboot.filter;

import javax.servlet.*;
import java.io.IOException;

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() {

    }
}

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@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());
           //默认拦截了 所有请求 包括青苔资源,但是不拦截jsp请求
		registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
		registration.setLoadOnStartup(
				this.webMvcProperties.getServlet().getLoadOnStartup());
		if (this.multipartConfig != null) {
			registration.setMultipartConfig(this.multipartConfig);
		}
		return registration;
	}

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<!-- 引入web模块 -->
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>

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@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@Import(BeanPostProcessorsRegistrar.class)
//导入BeanPostProcessorsRegistrar：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();
		}

	}

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public interface EmbeddedServletContainerFactory {

	EmbeddedServletContainer getEmbeddedServletContainer(
			ServletContextInitializer... initializers);
}

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public static class EmbeddedTomcat {

	@Bean
	public TomcatEmbeddedServletContainerFactory tomcatEmbeddedServletContainerFactory() {
		return new TomcatEmbeddedServletContainerFactory();
	}

}

//如果是 Jetty被使用  配置文件
@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();
	}

}

//如果是undertow配置文件
@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();
	}

}

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@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);
}

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protected TomcatEmbeddedServletContainer getTomcatEmbeddedServletContainer(
		Tomcat tomcat) {
	return new TomcatEmbeddedServletContainer(tomcat, getPort() >= 0);
}

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public TomcatEmbeddedServletContainer(Tomcat tomcat, boolean autoStart) {
	Assert.notNull(tomcat, "Tomcat Server must not be null");
	this.tomcat = tomcat;
	this.autoStart = autoStart;
	initialize();
}
private void initialize() throws EmbeddedServletContainerException {
	TomcatEmbeddedServletContainer.logger
			.info("Tomcat initialized with port(s): " + getPortsDescription(false));
	synchronized (this.monitor) {
		try {
			addInstanceIdToEngineName();
			try {
				// Remove service connectors to that protocol binding doesn't happen
				// yet
				removeServiceConnectors();

				// Start the server to trigger initialization listeners
				this.tomcat.start();

				// We can re-throw failure exception directly in the main thread
				rethrowDeferredStartupExceptions();

				Context context = findContext();
				try {
					ContextBindings.bindClassLoader(context, getNamingToken(context),
							getClass().getClassLoader());
				}
				catch (NamingException ex) {
					// Naming is not enabled. Continue
				}

				// Unlike Jetty, all Tomcat threads are daemon threads. We create a
				// blocking non-daemon to stop immediate shutdown
				startDaemonAwaitThread();
			}
			catch (Exception ex) {
				containerCounter.decrementAndGet();
				throw ex;
			}
		}
		catch (Exception ex) {
			throw new EmbeddedServletContainerException(
					"Unable to start embedded Tomcat", ex);
		}
	}
}

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@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata,
		BeanDefinitionRegistry registry) {
	if (this.beanFactory == null) {
		return;
	}
	registerSyntheticBeanIfMissing(registry,
			"embeddedServletContainerCustomizerBeanPostProcessor",
			EmbeddedServletContainerCustomizerBeanPostProcessor.class);
	registerSyntheticBeanIfMissing(registry,
			"errorPageRegistrarBeanPostProcessor",
			ErrorPageRegistrarBeanPostProcessor.class);
}

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//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;
}
//ServerProperties也是定制器

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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();
      }
   }
}