15-SpringBoot自动配置-切换内置web服务器
切换内置web服务器
SpringBoot的Web环境中默认使用tomcat作为内置服务器，其实SpringBoot提供了4种内置服务器供我们选择，我们可以很方便的切换。
演示案例
1.我们首先还是使用上一篇的项目，启动看看 Tomcat 作为内置 web 服务启动
首先要确认一下项目的 pom.xml 是否有 web 启动依赖：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
2.确认了存在依赖之后，我们在从源码查看内置的web服务器
我们首先打开外部库，依然是找到 autoconfigure 的包：
再找到 web 包，如下：
可以看到内置了几种web服务器。
/*
* Copyright 2012-2019 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
*
* https://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 reactor.netty.http.server.HttpServer;
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 }) // 只有配置了这些类的依赖，才会自动加载
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);
}
}
/**
* Nested configuration if Netty is being used.
*/
@Configuration
@ConditionalOnClass(HttpServer.class)
public static class NettyWebServerFactoryCustomizerConfiguration {
@Bean
public NettyWebServerFactoryCustomizer nettyWebServerFactoryCustomizer(Environment environment,
ServerProperties serverProperties) {
return new NettyWebServerFactoryCustomizer(environment, serverProperties);
}
}
}
也就是说，我们只要改变类的依赖，那么就应该可以切换内置的web服务器了。
3.查看 spring-boot-starter-web 启动依赖的内部继承关系
4.排除 tomcat 的依赖
image-20220224213305912
设置了排除之后，我们回头看看 pom.xml 里面的配置如下：
<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>
可以看到已经排除了依赖。
5.增加 jetty 依赖，使用 jetty 启动web服务
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<!-- 排除tomcat依赖 -->
<exclusions>
<exclusion>
<artifactId>spring-boot-starter-tomcat</artifactId>
<groupId>org.springframework.boot</groupId>
</exclusion>
</exclusions>
</dependency>
<!-- 配置jetty依赖 -->
<dependency>
<artifactId>spring-boot-starter-jetty</artifactId>
<groupId>org.springframework.boot</groupId>
</dependency>
