Tomcat 是一個基于組件的服務器，它的構成組件是可配置的，其中最外層的組件是 Catalina Servlet 容器，其他的組件都是按照一定的格式要求配置在這個頂層容器中。
Tomcat的各個組件在$CATALINA_HOME/conf/server.xml文件中配置，其基本結構如下：
<Server>
<Service>
<Connector />
<Engine>
<Host>
<Context />
</Host>
</Engine>
</Service>
<Server>
web.xml文件基本格式：(大小寫敏感、元素次序敏感)
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app PUBLIC "-//Sun Mivorsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<icon>
<small-icon>/images/app_small.gif</small-icon>
<large-icon>/images/app_large.gif</large-icon>
</icon>
<display-name>Application name</display-name>
<description>Description</description>
<distribute />
<context-param>
<param-name>contextParameter</param-name>
<param-value>test</param-value>
<description>It is a test parameter.</description>
</context-param>
<filter>
<filter-name>Set Character Encoding</filter-name>
<filter-class>filters.SetCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>EUC JP</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>Set Character Encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<listener>
<listener-class>listeners.SessionListener</listener-class>
</listener>
<servlet>
<servlet-name>snoop</servlet-name>
<servlet-class>SnoopServlet</servlet-class>
<init-param>
<param-name>foo</param-name>
<param-value>bar</param-value>
</init-param>
<run-as>
<description>Security role for anonymous access</description>
<role-name>tomcat</role-name>
</run-as>
<load-on-startup>1</load-on-statup>
</servlet>
<servlet>
<servlet-name>JspServlet</servlet-name>
<jsp-file>/test.jsp</jsp-file>
<init-param>
<param-name>firstName</param-name>
<param-value>tomcat</param-value>
</init-param>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>snoop</servlet-name>
<url-pattern>/snoop</servlet-name>
</servlet-mapping>
<session-config>
<session-timeout>120</session-timeout>
</session-config>
<mime-mapping>
<extension>htm</extension>
<mime-type>text/html</mime-type>
</mime-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<error-page>
<error-code>404</error-code>
<location>/404.jsp</location>
</error-page>
<error-page>
<exception-type>packagename.classname</exception-type>
<location>exception.jsp</location>
</error-page>
<taglib>
<taglib-url>http://jakarta.apache.org/tomcat/debug-taglib</taglib-uri>
<taglib-location>/WEB-INF/jsp/debug-taglib.tld</taglib-location>
</taglib>
<resource-env-ref>
<resource-env-ref-name>jms/StockQueue</resource-env-ref-name>
</resource-env-ref>
<resource-ref>
<res-ref-name>mail/Session</res-ref-name>
<res-type>javax.mail.Sesssion</res-type>
<res-auth>Container</res-auth>
<resource-ref>
<security-constraint>
<display-name>Example Security Constraint</display-name>
<web-resource-collection>
<web-resource-name>Protected Area</web-resource-name>
<url-pattern>/jsp/security/proctected/*</url-pattern>
<http-method>DELETE</http-method>
<http-method>GET</http-method>
<http-method>POST</http-method>
<http-method>PUT</http-method>
</web-resource-collection>
<auth-constraint>
<role-name>tomcat</role-name>
<role-name>role1</role-name>
</auth-constraint>
</security-constraint>
<login-config>
<auth-method>FORM</auth-method>
<realm-name>Example Form-Based Authentication Area</realm-name>
<form-login-config>
<form-login-page>/jsp/security/protected/login.jsp</form-login-page>
<form-error-page>/jsp/security/protected/error.jsp</form-error-page>
</form-login-config>
</login-config>
<security-role>
<role-name>tomcat</role-name>
</security-role>
<env-entry>
<env-entry-name>minExemptions</env-entry-name>
<env-entry-value>1</env-entry-value>
<env-entry-type>java.lang.Integer</env-entry-type>
</env-entry>
<ejb-ref>
<description>Example EJB Reference</description>
<ejb-ref-name>ejb/Account</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<home>com.mycompany.mypackage.AccountHome</home>
<remote>com.mycompany.mypackage.AccountRemote</remote>
</ejb-ref>
<ejb-local-ref>
<description>Example Local EJB Reference</description>
<ejb-ref-name>ejb/ProcessOrder</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home>com.mycompany.mypackage.ProcessOrderHome</local-home>
<local>com.mycompany.mypackage.ProcessOrder</local>
</ejb-local-ref>
</web-app>
servlet 2.4中新增標簽：
<locale-encoding-mapping-list>
<locale-encoding-mapping>
<locale>ja</locale>
<encoding>Shift_JIS</encoding>
</locale-encoding-mapping>
<locale-encoding-mapping>
<locale>zh_TW</locale>
<encoding>Big5</encoding>
</locale-encoding-mapping>
</locale-encoding-mapping-list>
<filter-mapping>
<filter-name>Logging Filter</filter-name>
<url-pattern>/products/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
<dispatcher>INCLUDE</dispatcher>
<dispatcher>ERROR</dispatcher>
</filter-mapping>
<jsp-config>
<taglib>
<taglib-uri>Taglib</taglib-uri>
<taglib-location>/WEB-INF/tlds/mytaglib.tld</taglib-location>
</taglib>
<jsp-property-group>
<description>Special property group for jsp configuration.</description>
<display-name>JspConfiguration</display-name>
<url-pattern>/jsp/*</url-pattern>
<el-ignored>true</el-ignored>
<page-encoding>UTF-8</page-encoding>
<scripting-invalid>true</scripting-invalid>
<include--prelude>/include/prelude.jsp</include-prelude>
<include-coda>/include/coda.jsp</include-coda>
</jsp-property-group>
</jsp-config>