通过阅读springboot源码看看springboot是怎么加载tomcat的

淩亂°似流年 2023-02-26 02:13 10阅读 0赞

1.springboot项目启动类找到@SpringBootApplication注解点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70]  
2.可以看到他上面有个@EnableAutoConfiguration启用自动配置,点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 1]  
3.可以看到导入了一个AutoConfigurationImportSelector自动配置导入选择器,继续点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 2]  
4.他会去找一个META-INF/spring.factories配置文件里面有很多配置信息  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 3]  
5.去导入的依赖里面找到这个文件打开  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 4]  
6.ServletWebServerFactoryAutoConfiguration找到这个点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 5]  
6.1可以看到有一个tomcatServletWebServerFactoryCustomizer方法传过来的参数ServerProperties一些端口啊地址之类的信息,返回了一个TomcatServletWebServerFactoryCustomizer点进去看看  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 6]  
6.2TomcatServletWebServerFactoryCustomizer这个类实现了一个WebServerFactoryCustomizer接口那必然实现了customize这个方法  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 7]  
6.3这个方法就是把tomcat初始化了  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 8]  
7.返回去可以看到 导入了这么一个玩意儿EmbeddedTomcat继续点进去看看是啥  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 9]  
8.在这里补充一个知识点哈  
@ConditionalOnClass(\{ Servlet.class, Tomcat.class, UpgradeProtocol.class \})  
:这注解的意思是后面三个实例存在才会把EmbeddedTomcat注册到IOC容器  
@ConditionalOnMissingBean(value = ServletWebServerFactory.class, search = SearchStrategy.CURRENT):  
这个注解的意思是如果IOC容器里没有EmbeddedTomcat这个bean 那么就会把EmbeddedTomcat加载到容器里  
回归正题:  
TomcatServletWebServerFactory点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 10]  
9.可以看到有个getWebServer方法 new了个Tomcat对象并且设置了一些属性值(其实就是初始化了tomcat但是这个地方并没有启动)  
然后返回了个getTomcatWebServer点进去看看![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 11]  
10.看返回值 创建了个TomcatWebServer并且把初始化的tomcat传过来了还有看看端口号是不是>=0;继续TomcatWebServer点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 12]  
11.创建了一个TomcatWebServer实例 可以看到两个参数 一个是初始化的tomcat  
一个是是否自动启动;还调用了个initialize()方法 点进去  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 13]  
12.看看终于看到了启动tomcat服务器  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1Rhb1NoYW81MjE_size_16_color_FFFFFF_t_70 14]

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