（一）Tomcat源码阅读：查看官网，厘清大概轮廓

一、进入官网

点击以下链接进入官网:Apache Tomcat® - Welcome!,点击介绍进入介绍，查看tomcat的项目结构。

二、查看项目结构

进入介绍后，我们可以看到下面的这些东西，这些对于tomcat是比较重要的，我们要一一对其进行解读。

这段话的主要意思是/bin，/conf,/logs和/webapps是最重要的几个文件夹。/bin文件夹中存放着启动，停止和其它脚本,.sh和.bat拥有这相同的功能不过.sh是在unix中使用，.bat是在windows中使用。/conf文件夹中存放着tomcat中最重要的配置文件。 /logs文件夹是默认的日志输出地址。/webapps是你自己的应用所在地。

Directories and Files

These are some of the key tomcat directories:

• /bin - Startup, shutdown, and other scripts. The *.sh files (for Unix systems) are functional duplicates of the *.bat files (for Windows systems). Since the Win32 command-line lacks certain functionality, there are some additional files in here.
• /conf - Configuration files and related DTDs. The most important file in here is server.xml. It is the main configuration file for the container.
• /logs - Log files are here by default.
• /webapps - This is where your webapps go.

 这段话的主要意思是：通过上面的文档，它们都指向了下面两个重要的属性。CATALINA_HOME展示了tomcat的安装位置。CATALINA_BASE展示了运行时应用需要的配置文件，如果你想要多个实例，你可以在CATALINA_BASE中进行配置。CATALINA_HOME中配置了一些静态的不太需要改变的东西，例如jar包或者二进制文件，而CATALINA_BASE中配置了一些变化的东西，例如:配置文件，日志等。

CATALINA_HOME and CATALINA_BASE

Throughout the documentation, there are references to the two following properties:

• CATALINA_HOME: Represents the root of your Tomcat installation, for example /home/tomcat/apache-tomcat-9.0.10 or C:\Program Files\apache-tomcat-9.0.10.
• CATALINA_BASE: Represents the root of a runtime configuration of a specific Tomcat instance. If you want to have multiple Tomcat instances on one machine, use the CATALINA_BASE property.

If you set the properties to different locations, the CATALINA_HOME location contains static sources, such as .jar files, or binary files. The CATALINA_BASE location contains configuration files, log files, deployed applications, and other runtime requirements.

这段话是意思主要解释了使用了CATALINA_HOME 和 CATALINA_BASE的原因：1、各个应用共享一个CATALINA_HOME有利于应用升级。2、避免重复部署jar包。3、可以共享相同的配置。

Why Use CATALINA_BASE

By default, CATALINA_HOME and CATALINA_BASE point to the same directory. Set CATALINA_BASE manually when you require running multiple Tomcat instances on one machine. Doing so provides the following benefits:

• Easier management of upgrading to a newer version of Tomcat. Because all instances with single CATALINA_HOME location share one set of .jar files and binary files, you can easily upgrade the files to newer version and have the change propagated to all Tomcat instances using the same CATALIA_HOME directory.
• Avoiding duplication of the same static .jar files.
• The possibility to share certain settings, for example the setenv shell or bat script file (depending on your operating system).

三、总结

通过以上的官方文档，我们知道了tomcat最重要的文件夹是CATALINA_HOME 和 CATALINA_BASE，以及使用两个文件夹的好处，但是我们对于项目的结构还很模糊，我还需要通过官网进一步了解tomcat的项目结构。我会在接下来的文章中进行介绍。