Tomcat源码---载入相应的资源及解析四(2)

boss44

　　一,根据以上文章所讲的对server.xml的解析作下简单的分析
　　org.apache.catalina.startup.Catalina#load
　　Digester是用sax来解析server.xml的类,这一步是初始化

• //创建该对象,主要是对conf/server.xml进行解析  
  
•        Digester digester = createStartDigester(); 
  

　　tomcat文档的解析如下:
　　--------------------------------------------------------------------------------------------
　　b3) createStartDigester() 
　　Configures a digester for the main server.xml elements like
　　org.apache.catalina.core.StandardServer (can change of course :)
　　org.apache.catalina.deploy.NamingResources
　　Stores naming resources in the J2EE JNDI tree
　　org.apache.catalina.LifecycleListener
　　implements events for start/stop of major components
　　org.apache.catalina.core.StandardService
　　The single entry for a set of connectors,
　　so that a container can listen to multiple connectors
　　ie, single entry
　　org.apache.coyote.tomcat5.CoyoteConnector
　　Connectors to listen for incoming requests only
　　It also adds the following rulesets to the digester
　　NamingRuleSet
　　EngineRuleSet
　　HostRuleSet
　　ContextRuleSet
　　b4) Load the server.xml and parse it using the digester
　　    Parsing the server.xml using the digester is an automatic
　　    XML-object mapping tool, that will create the objects defined in server.xml
　　    Startup of the actual container has not started yet.
　　b5) Assigns System.out and System.err to the SystemLogHandler class
　　b6) Calls intialize on all components, this makes each object register itself with the 
　　    JMX agent.
　　    During the process call the Connectors also initialize the adapters.
　　    The adapters are the components that do the request pre-processing.
　　    Typical adapters are HTTP1.1 (default if no protocol is specified,
　　    org.apache.coyote.http11.Http11Protocol)
　　    AJP1.3 for mod_jk etc.



　　--------------------------------------------------------------------------------------------
　　org.apache.catalina.startup.Catalina#createStartDigester

//Create and configure the Digester we will be using for startup.
protected Digester createStartDigester() {
long t1=System.currentTimeMillis();
// Initialize the digester
Digester digester = new Digester();
digester.setValidating(false);
digester.setRulesValidation(true);
HashMap<Class, List<String>> fakeAttributes = new HashMap<Class, List<String>>();
ArrayList<String> attrs = new ArrayList<String>();
attrs.add("className");
fakeAttributes.put(Object.class, attrs);
digester.setFakeAttributes(fakeAttributes);
digester.setClassLoader(StandardServer.class.getClassLoader());
// Configure the actions we will be using
//1,server标签.2,默认初始化的类,若在xml上有自定义,覆盖此类,3,属性名
digester.addObjectCreate("Server",
"org.apache.catalina.core.StandardServer",
"className");
// 设定一个SetPropertiesRule，这个规则是用于堆栈顶端元素的属性设置  
digester.addSetProperties("Server");
//设置下一个server的标签,总是先外再到内,,按这三种模式可推出以下的设置
digester.addSetNext("Server",
"setServer",
"org.apache.catalina.Server");
digester.addObjectCreate("Server/GlobalNamingResources",
"org.apache.catalina.deploy.NamingResources");
digester.addSetProperties("Server/GlobalNamingResources");
digester.addSetNext("Server/GlobalNamingResources",
"setGlobalNamingResources",
"org.apache.catalina.deploy.NamingResources");
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");
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");
//Executor
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");

digester.addRule("Server/Service/Connector",
new ConnectorCreateRule());
digester.addRule("Server/Service/Connector",
new SetAllPropertiesRule(new String[]{"executor"}));
digester.addSetNext("Server/Service/Connector",
"addConnector",
"org.apache.catalina.connector.Connector");


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");
// Add RuleSets for nested elements
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/"));
digester.addRuleSet(ClusterRuleSetFactory.getClusterRuleSet("Server/Service/Engine/Host/Cluster/"));
digester.addRuleSet(new NamingRuleSet("Server/Service/Engine/Host/Context/"));
// When the 'engine' is found, set the parentClassLoader.
digester.addRule("Server/Service/Engine",
new SetParentClassLoaderRule(parentClassLoader));
digester.addRuleSet(ClusterRuleSetFactory.getClusterRuleSet("Server/Service/Engine/Cluster/"));
long t2=System.currentTimeMillis();
if (log.isDebugEnabled())
log.debug("Digester for server.xml created " + ( t2-t1 ));
return (digester);
}
 　　//要查看digester的解析可查看how tomcat work 这本书的第十五章,有详细介绍

• inputSource.setByteStream(inputStream);  
  
•            //把Catalina这个类压入栈顶部  
  
•            digester.push(this);  
  
•     //压入顶部之后,在digester中就可以此类与server.xml进行相应的解析,比如该类的server实例化  
  
•            digester.parse(inputSource);  
  
•            inputStream.close();  
  

　　digester.push(this);把该对象压入到栈中,以便为这个类中的属性进行初始化,如Server
　　digester.parse(inputSource);为对里面所设置的对象进行初始化等一系列操作.