Server.xml解析

来源

本文整理自 <Tomcat内核设计剖析>、<Tomcat结构解析> 加上自己的理解、源码来自 Tomcat8.5 版本

<Server port="8005" shutdown="SHUTDOWN">

  <Listener className="org.apache.catalina.startup.VersionLoggerListener" />

  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />

  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />

  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />

  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <GlobalNamingResources>

    <Resource name="UserDatabase" auth="Container"

              type="org.apache.catalina.UserDatabase"

              description="User database that can be updated and saved"

              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"

              pathname="conf/tomcat-users.xml" />

  </GlobalNamingResources>

  <Service name="Catalina">

    <Connector port="8080" protocol="HTTP/1.1"

               connectionTimeout="20000"

               redirectPort="8443" />

    <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />

    <Engine name="Catalina" defaultHost="localhost">

      <Realm className="org.apache.catalina.realm.LockOutRealm">

        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"

               resourceName="UserDatabase"/>

      </Realm>

      <Host name="localhost"  appBase="webapps"

            unpackWARs="true" autoDeploy="true">

        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"

               prefix="localhost_access_log" suffix=".txt"

               pattern="%h %l %u %t &quot;%r&quot; %s %b" />

      </Host>

    </Engine>

  </Service>

</Server>

// org.apache.catalina.startup.Catalina.java

public void load() {

    digester.parse(inputSource);

}

Catalina使用Digester解析XML配置文件并创建应用服务器。

Digester是一款用于将XML转化成Java对象的事件驱动型工具，针对SAX的进一步封装。Digester对SAX事件提供了更加友好的接口，隐藏了XML节点具体的层次细节。目前是Apache Commons项目。

Digester通过流读取XML文件，当识别出特定XML节点后便会执行特定的动作、或者创建Java对象，或者执行对象的某个方法。核心是：匹配模式和处理规则。

Digester是非线程安全的。

Server解析

创建Server实例

Catalina中Server默认实现 StandardServer、Digester创建Server实例后，设置Server相关属性，并将其设置到Catalina对象中(调用setServer)

digester.addObjectCreate("Server",

                         "org.apache.catalina.core.StandardServer",

                         "className");

digester.addSetProperties("Server");

digester.addSetNext("Server",

                    "setServer",

                    "org.apache.catalina.Server");

创建全局命名资源

Catalina根据GlobalNamingResources配置创建全局的命名资源上下文(JNDI)，设置属性并将其设置到Server实例中(setGlobalNamingResources)

digester.addObjectCreate("Server/GlobalNamingResources",

                         "org.apache.catalina.deploy.NamingResourcesImpl");

digester.addSetProperties("Server/GlobalNamingResources");

digester.addSetNext("Server/GlobalNamingResources",

                    "setGlobalNamingResources",

                    "org.apache.catalina.deploy.NamingResourcesImpl");

Server添加生命周期监听器

Server元素支持配置Listener节点，用于为当前的Server实例添加LifecycleListener监听器，由classNmae属性指定，默认配置了5个监听器：

digester.addObjectCreate("Server/Listener",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties("Server/Listener");

digester.addSetNext("Server/Listener",

                    "addLifecycleListener",

                    "org.apache.catalina.LifecycleListener");

digester.addObjectCreate("Server/Service",

                         "org.apache.catalina.core.StandardService",

                         "className");

digester.addSetProperties("Server/Service");

digester.addSetNext("Server/Service",

                    "addService",

                    "org.apache.catalina.Service");

创建Service实例

Server添加Service实例，Catalina默认的Service实例是 StandardServie，可以通过addService()添加到Server实例中。

digester.addObjectCreate("Server/Service",

                         "org.apache.catalina.core.StandardService",

                         "className");

digester.addSetProperties("Server/Service");

digester.addSetNext("Server/Service",

                    "addService",

                    "org.apache.catalina.Service");

Service添加生命周期监听器

由className 属性指定，默认未指定Service监听器。

digester.addObjectCreate("Server/Service/Listener",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties("Server/Service/Listener");

digester.addSetNext("Server/Service/Listener",

                    "addLifecycleListener",

                    "org.apache.catalina.LifecycleListener");

Service添加Executor

默认实现StandardThreadExecutor，由className属性指定具体实现类，Catalina共享Executor的级别是Service。默认未配置。

digester.addObjectCreate("Server/Service/Executor",

                         "org.apache.catalina.core.StandardThreadExecutor",

                         "className");

digester.addSetProperties("Server/Service/Executor");

digester.addSetNext("Server/Service/Executor",

                    "addExecutor",

                    "org.apache.catalina.Executor");

Service添加Connector

在设置属性时，将executor和sslImplementationName属性排除。在Connector创建时，会判断当前是否指定了executor属性，如果是，从Service中查找该名称的executor并设置到Connector中。在创建Connector时也会判断是否有sslImplementationName属性，如果是，将属性设置到使用的协议中，指定了一个SSL实现。

digester.addRule("Server/Service/Connector",

                 new ConnectorCreateRule());

digester.addRule("Server/Service/Connector",

                 new SetAllPropertiesRule(new String[]{"executor", "sslImplementationName"}));

digester.addSetNext("Server/Service/Connector",

                    "addConnector",

                    "org.apache.catalina.connector.Connector");

Connector添加虚拟主机SSL配置

digester.addObjectCreate("Server/Service/Connector/SSLHostConfig",

                         "org.apache.tomcat.util.net.SSLHostConfig");

digester.addSetProperties("Server/Service/Connector/SSLHostConfig");

digester.addSetNext("Server/Service/Connector/SSLHostConfig",

                    "addSslHostConfig",

                    "org.apache.tomcat.util.net.SSLHostConfig");

digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate",

                 new CertificateCreateRule());

digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate",

                 new SetAllPropertiesRule(new String[]{"type"}));

digester.addSetNext("Server/Service/Connector/SSLHostConfig/Certificate",

                    "addCertificate",

                    "org.apache.tomcat.util.net.SSLHostConfigCertificate");

Connector添加生命周期监听器

默认情况下，未指定。

digester.addObjectCreate("Server/Service/Connector/Listener",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties("Server/Service/Connector/Listener");

digester.addSetNext("Server/Service/Connector/Listener",

                    "addLifecycleListener",

                    "org.apache.catalina.LifecycleListener");

Connector添加升级协议

用于支持HTTP/2，8.5.6新增的配置。

digester.addObjectCreate("Server/Service/Connector/UpgradeProtocol",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties("Server/Service/Connector/UpgradeProtocol");

digester.addSetNext("Server/Service/Connector/UpgradeProtocol",

                    "addUpgradeProtocol",

                    "org.apache.coyote.UpgradeProtocol");

子元素解析规则

指定了Servlet容器相关的嵌套子节点的解析规则，而且每类嵌套子节点的解析封装为一个RuleSet，包含

GlobalNamingResource、Engine、Host、Cluster、Context

digester.addRuleSet(new NamingRuleSet("Server/GlobalNamingResources/"));

digester.addRuleSet(new EngineRuleSet("Server/Service/"));

digester.addRuleSet(new HostRuleSet("Server/Service/Engine/"));

digester.addRuleSet(new ContextRuleSet("Server/Service/Engine/Host/"));

addClusterRuleSet(digester, "Server/Service/Engine/Host/Cluster/");

digester.addRuleSet(new NamingRuleSet("Server/Service/Engine/Host/Context/"));

digester.addRule("Server/Service/Engine",

                 new SetParentClassLoaderRule(parentClassLoader));

addClusterRuleSet(digester, "Server/Service/Engine/Cluster/");

Engine解析

在EngineRuleSet类下，创建Engine实例，并通过setContainer方法添加到Service实例，Catalina默认实现为StandardEngine。默认为Engine添加了一个生命周期监听器 EngineConfig。（用于打印Engine启动和停止日志）

digester.addObjectCreate(prefix + "Engine",

                         "org.apache.catalina.core.StandardEngine",

                         "className");

digester.addSetProperties(prefix + "Engine");

digester.addRule(prefix + "Engine",

                 new LifecycleListenerRule

                         ("org.apache.catalina.startup.EngineConfig",

                          "engineConfigClass"));

digester.addSetNext(prefix + "Engine",

                    "setContainer",

                    "org.apache.catalina.Engine");

Engine添加集群配置

digester.addObjectCreate(prefix + "Engine/Cluster",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Engine/Cluster");

digester.addSetNext(prefix + "Engine/Cluster",

                    "setCluster",

                    "org.apache.catalina.Cluster");

Engine添加生命周期监听器

此处与EngineConfig不同，这里由server.xml 配置。默认未指定。

digester.addObjectCreate(prefix + "Engine/Listener",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Engine/Listener");

digester.addSetNext(prefix + "Engine/Listener",

                    "addLifecycleListener",

                    "org.apache.catalina.LifecycleListener");

Engine添加安全配置和Valve

为Engine添加安全配置(RealmRuleSet)，添加Valve拦截器。

digester.addObjectCreate(pattern, null /* MUST be specified in the element */,

                         "className");

digester.addSetProperties(pattern);

digester.addSetNext(pattern, methodName, "org.apache.catalina.Realm");

digester.addRuleSet(new CredentialHandlerRuleSet(pattern + "/"));

digester.addObjectCreate(prefix + "Engine/Valve",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Engine/Valve");

digester.addSetNext(prefix + "Engine/Valve",

                    "addValve",

                    "org.apache.catalina.Valve");

Host的解析

创建Host实例

位于HostRuleSet类中。创建Host实例，通过addChild方法添加到Engine中，Catalina默认实现 StandardHost，同时注册了一个生命周期监听器 HostConfig，该监听器在 Web应用部署中做了大量工作，同时Host还可以通过 Alias 支持配置别名。

digester.addObjectCreate(prefix + "Host",

                         "org.apache.catalina.core.StandardHost",

                         "className");

digester.addSetProperties(prefix + "Host");

digester.addRule(prefix + "Host",

                 new CopyParentClassLoaderRule());

digester.addRule(prefix + "Host",

                 new LifecycleListenerRule

                         ("org.apache.catalina.startup.HostConfig",

                          "hostConfigClass"));

digester.addSetNext(prefix + "Host",

                    "addChild",

                    "org.apache.catalina.Container");

digester.addCallMethod(prefix + "Host/Alias",

                       "addAlias", 0);

Host添加集群

Cluster可以配置在 Engine ，还可以配置在Engine级别。

digester.addObjectCreate(prefix + "Host/Cluster",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Host/Cluster");

digester.addSetNext(prefix + "Host/Cluster",

                    "setCluster",

                    "org.apache.catalina.Cluster");

Host添加生命周期监听器

此配置由 server.xml 配置，默认；无

digester.addObjectCreate(prefix + "Host/Listener",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Host/Listener");

digester.addSetNext(prefix + "Host/Listener",

                    "addLifecycleListener",

                    "org.apache.catalina.LifecycleListener");

Host添加安全配置和Valve

Valve默认是 AccessLogValve。用于记录访问日志。

digester.addObjectCreate(pattern, null /* MUST be specified in the element */,

                         "className");

digester.addSetProperties(pattern);

digester.addSetNext(pattern, methodName, "org.apache.catalina.Realm");

digester.addRuleSet(new CredentialHandlerRuleSet(pattern + "/"));

digester.addObjectCreate(prefix + "Host/Valve",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Host/Valve");

digester.addSetNext(prefix + "Host/Valve",

                    "addValve",

                    "org.apache.catalina.Valve");

Context解析

这里对的Context配置，仅仅指 server.xml 中配置，默认情况下，在server.xml 中不配置。通过 HostConfig 自动扫描部署目录，以 context.xml 文件为基础进行解析创建。

创建Context实例

位于ContextRuleSet类中。create==true时，创建Context实例，通过 HostConfig 自动创建Context时，create=false，默认实现类是 StandardContext。在创建实例时，添加了一个生命周期监听器 ContextConfig，用于详细配置 Context，如解析 web.xml 等。

if (create) {

    digester.addObjectCreate(prefix + "Context",

                             "org.apache.catalina.core.StandardContext", "className");

    digester.addSetProperties(prefix + "Context");

} else {

    digester.addRule(prefix + "Context", new SetContextPropertiesRule());

}

if (create) {

    digester.addRule(prefix + "Context",

                     new LifecycleListenerRule

                     ("org.apache.catalina.startup.ContextConfig",

                      "configClass"));

    digester.addSetNext(prefix + "Context",

                        "addChild",

                        "org.apache.catalina.Container");

}

Context添加生命周期监听器

此配置由 server.xml 配置，默认；无

digester.addObjectCreate(prefix + "Context/Listener",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Context/Listener");

digester.addSetNext(prefix + "Context/Listener",

                    "addLifecycleListener",

                    "org.apache.catalina.LifecycleListener");

Context指定类加载器

默认 WebappLoader。

digester.addObjectCreate(prefix + "Context/Loader",

                         "org.apache.catalina.loader.WebappLoader",

                         "className");

digester.addSetProperties(prefix + "Context/Loader");

digester.addSetNext(prefix + "Context/Loader",

                    "setLoader",

                    "org.apache.catalina.Loader");

Context添加会话管理器

默认是：StandardManager，同时为管理器指定了会话存储方式和会话标识生成器。

digester.addObjectCreate(prefix + "Context/Manager",

                         "org.apache.catalina.session.StandardManager",

                         "className");

digester.addSetProperties(prefix + "Context/Manager");

digester.addSetNext(prefix + "Context/Manager",

                    "setManager",

                    "org.apache.catalina.Manager");

digester.addObjectCreate(prefix + "Context/Manager/Store",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Context/Manager/Store");

digester.addSetNext(prefix + "Context/Manager/Store",

                    "setStore",

                    "org.apache.catalina.Store");

digester.addObjectCreate(prefix + "Context/Manager/SessionIdGenerator",

                         "org.apache.catalina.util.StandardSessionIdGenerator",

                         "className");

digester.addSetProperties(prefix + "Context/Manager/SessionIdGenerator");

digester.addSetNext(prefix + "Context/Manager/SessionIdGenerator",

                    "setSessionIdGenerator",

                    "org.apache.catalina.SessionIdGenerator");

Context添加初始化参数

digester.addObjectCreate(prefix + "Context/Parameter",

"org.apache.tomcat.util.descriptor.web.ApplicationParameter");

digester.addSetProperties(prefix + "Context/Parameter");

digester.addSetNext(prefix + "Context/Parameter",

                    "addApplicationParameter",

                    "org.apache.tomcat.util.descriptor.web.ApplicationParameter");

Context添加安全配置和Web资源配置

Tomcat8中新增了 PreResources、JarResources、PostResources三种资源的配置。在加载Web应用时使用。

digester.addRuleSet(new RealmRuleSet(prefix + "Context/"));

digester.addObjectCreate(prefix + "Context/Resources",

                         "org.apache.catalina.webresources.StandardRoot",

                         "className");

digester.addSetProperties(prefix + "Context/Resources");

digester.addSetNext(prefix + "Context/Resources",

                    "setResources",

                    "org.apache.catalina.WebResourceRoot");

digester.addObjectCreate(prefix + "Context/Resources/PreResources",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Context/Resources/PreResources");

digester.addSetNext(prefix + "Context/Resources/PreResources",

                    "addPreResources",

                    "org.apache.catalina.WebResourceSet");

digester.addObjectCreate(prefix + "Context/Resources/JarResources",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Context/Resources/JarResources");

digester.addSetNext(prefix + "Context/Resources/JarResources",

                    "addJarResources",

                    "org.apache.catalina.WebResourceSet");

digester.addObjectCreate(prefix + "Context/Resources/PostResources",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Context/Resources/PostResources");

digester.addSetNext(prefix + "Context/Resources/PostResources",

                    "addPostResources",

                    "org.apache.catalina.WebResourceSet");

Context添加资源链接

添加 ContextResourceLink，用于J2EE命名服务（JNDI）

digester.addObjectCreate(prefix + "Context/ResourceLink",

"org.apache.tomcat.util.descriptor.web.ContextResourceLink");

digester.addSetProperties(prefix + "Context/ResourceLink");

digester.addRule(prefix + "Context/ResourceLink",

                 new SetNextNamingRule("addResourceLink",                         "org.apache.tomcat.util.descriptor.web.ContextResourceLink"));

Context添加Valve

digester.addObjectCreate(prefix + "Context/Valve",

                         null, // MUST be specified in the element

                         "className");

digester.addSetProperties(prefix + "Context/Valve");

digester.addSetNext(prefix + "Context/Valve",

                    "addValve",

                    "org.apache.catalina.Valve");

Context添加守护资源配置

WatchedResource：用于为Context添加监视资源，当这些资源发生变更时，Web应用会被重新加载。默认值：/WEB-INF/web.xml。在 conf/context.xml 中配置。

WrapperLifecycle：为Context添加一个监听器类，添加到Context 包含的 Wrapper 上。

JarScanner：默认实现是 StandardJarScanner。StandardJarScanner 扫描Web应用和类加载器层级的Jar包，主要用于TLD扫描和web-fragement.xml扫描。还可以为 JarScanner 指定一个Filter，只有符合的才会被处理。默认Filter：StandardJarScanFilter。

digester.addCallMethod(prefix + "Context/WatchedResource",

                       "addWatchedResource", 0);

digester.addCallMethod(prefix + "Context/WrapperLifecycle",

                       "addWrapperLifecycle", 0);

digester.addCallMethod(prefix + "Context/WrapperListener",

                       "addWrapperListener", 0);

digester.addObjectCreate(prefix + "Context/JarScanner",

                         "org.apache.tomcat.util.scan.StandardJarScanner",

                         "className");

digester.addSetProperties(prefix + "Context/JarScanner");

digester.addSetNext(prefix + "Context/JarScanner",

                    "setJarScanner",

                    "org.apache.tomcat.JarScanner");

digester.addObjectCreate(prefix + "Context/JarScanner/JarScanFilter",

                         "org.apache.tomcat.util.scan.StandardJarScanFilter",

                         "className");

digester.addSetProperties(prefix + "Context/JarScanner/JarScanFilter");

digester.addSetNext(prefix + "Context/JarScanner/JarScanFilter",

                    "setJarScanFilter",

                    "org.apache.tomcat.JarScanFilter");

Context添加Cookie处理器

Tomcat8.5版本从 LegacyCookieProcessor 改成 Rfc6265CookieProcessor。

digester.addObjectCreate(prefix + "Context/CookieProcessor",

"org.apache.tomcat.util.http.Rfc6265CookieProcessor",

"className");

digester.addSetProperties(prefix + "Context/CookieProcessor");

digester.addSetNext(prefix + "Context/CookieProcessor",

"setCookieProcessor",

"org.apache.tomcat.util.http.CookieProcessor");