SpringBoot+Tomcat源代码解读

大家知道，SpringBoot内嵌Tomcat服务器，那么除了Tomcat服务器，SpringBoot还支持哪些Web服务器呢？我们来看看源码。

/*
 * Copyright 2012-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.autoconfigure.web.embedded;

import io.undertow.Undertow;
import org.apache.catalina.startup.Tomcat;
import org.apache.coyote.UpgradeProtocol;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.util.Loader;
import org.eclipse.jetty.webapp.WebAppContext;
import org.xnio.SslClientAuthMode;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;

/**
 * {@link EnableAutoConfiguration Auto-configuration} for embedded servlet and reactive
 * web servers customizations.
 *
 * @author Phillip Webb
 * @since 2.0.0
 */
@Configuration
@ConditionalOnWebApplication
@EnableConfigurationProperties(ServerProperties.class)
public class EmbeddedWebServerFactoryCustomizerAutoConfiguration {

	/**
	 * Nested configuration if Tomcat is being used.
	 */
	@Configuration
	@ConditionalOnClass({ Tomcat.class, UpgradeProtocol.class })
	public static class TomcatWebServerFactoryCustomizerConfiguration {

		@Bean
		public TomcatWebServerFactoryCustomizer tomcatWebServerFactoryCustomizer(
				Environment environment, ServerProperties serverProperties) {
			return new TomcatWebServerFactoryCustomizer(environment, serverProperties);
		}

	}

	/**
	 * Nested configuration if Jetty is being used.
	 */
	@Configuration
	@ConditionalOnClass({ Server.class, Loader.class, WebAppContext.class })
	public static class JettyWebServerFactoryCustomizerConfiguration {

		@Bean
		public JettyWebServerFactoryCustomizer jettyWebServerFactoryCustomizer(
				Environment environment, ServerProperties serverProperties) {
			return new JettyWebServerFactoryCustomizer(environment, serverProperties);
		}

	}

	/**
	 * Nested configuration if Undertow is being used.
	 */
	@Configuration
	@ConditionalOnClass({ Undertow.class, SslClientAuthMode.class })
	public static class UndertowWebServerFactoryCustomizerConfiguration {

		@Bean
		public UndertowWebServerFactoryCustomizer undertowWebServerFactoryCustomizer(
				Environment environment, ServerProperties serverProperties) {
			return new UndertowWebServerFactoryCustomizer(environment, serverProperties);
		}

	}

}

这是SpringBoot自动配置内嵌Web服务器的代码，从注释中我们可以看出，SpringBoot支持Tomcat、Jetty、Undertow三个服务器，当然默认使用的是Tomcat服务器。如果我们要切换成其他Web服务器，则要先移除spring-boot-starter-tomcat这个包，导入其他两个jar包，分别是spring-boot-starter-jetty和spring-boot-starter-undertow

 

gradle移除jar包的做法是

dependencies {
    compile("org.gradle.test.excludes:api:1.0") {
        exclude module: 'shared'
    }
}

maven的做法是

<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>

Tomcat的核心组件是Connector，Connector的处理逻辑可以参考这篇文章

https://blog.youkuaiyun.com/linxdcn/article/details/73382570

http://blog.youkuaiyun.com/linxdcn/article/details/73527465

 

Tomcat服务器默认使用Http11NioProtocol，不清楚是什么的可以看下这篇博文https://blog.youkuaiyun.com/jeff_fangji/article/details/43909677

与Http11NioProtocol相对的协议是Http11Protocol，这个协议已经过时，将会在Tomcat9移除。

 

Http11NioProtocol类的唯一构造函数使用了NioEndpoint来构造成员变量

如果要换其他Protocol，可以参考这篇博文进行配置 

 

NioEndPoint默认设置

PollerThread 

默认名：http-nio-端口号-ClientPoller-序号，例如http-nio-8080-ClientPoller-0

默认数量：2

如果使用Http11NioProtocol来替代NioEndPoint，则可以修改默认数量配置（Http11NioProtocol是NioEndPoint的实现类）。

    // -------------------- Pool setup --------------------

    public void setPollerThreadCount(int count) {
        ((NioEndpoint)getEndpoint()).setPollerThreadCount(count);
    }

 

 

先启动PollerThread，再启动AcceptorThread

AcceptorThread 默认数量是 1，可以设置

    /**
     * Acceptor thread count.
     */
    protected int acceptorThreadCount = 1;