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在前一章查看tomcat启动文件都干点啥---Bootstrap.java中我们得出结论，在Bootstrap中通过反射调用Catalina类中的getServer,start,stop,stopServer等方法，下面看一下Catalina类中给外部提供的公共方法：
Start:其中Catalina类的入口当然是start方法.start方法实现了启动一个新的server事例的功能，看一下start方法的内容：
1 public void start() {
2
3 if (getServer() == null) {
4 load();
5 }
6
7 if (getServer() == null) {
8 log.fatal("Cannot start server. Server instance is not configured.");
9 return;
10 }
11
12 long t1 = System.nanoTime();
13
14 // Start the new server
15 try {
16 getServer().start();
17 } catch (LifecycleException e) {
18 log.fatal(sm.getString("catalina.serverStartFail"), e);
19 try {
20 getServer().destroy();
21 } catch (LifecycleException e1) {
22 log.debug("destroy() failed for failed Server ", e1);
23 }
24 return;
25 }
26
27 long t2 = System.nanoTime();
28 if(log.isInfoEnabled()) {
29 log.info("Server startup in " + ((t2 - t1) / 1000000) + " ms");
30 }
31
32 // Register shutdown hook
33 if (useShutdownHook) {
34 if (shutdownHook == null) {
35 shutdownHook = new CatalinaShutdownHook();
36 }
37 Runtime.getRuntime().addShutdownHook(shutdownHook);
38
39 // If JULI is being used, disable JULI's shutdown hook since
40 // shutdown hooks run in parallel and log messages may be lost
41 // if JULI's hook completes before the CatalinaShutdownHook()
42 LogManager logManager = LogManager.getLogManager();
43 if (logManager instanceof ClassLoaderLogManager) {
44 ((ClassLoaderLogManager) logManager).setUseShutdownHook(
45 false);
46 }
47 }
48
49 if (await) {
50 await();
51 stop();
52 }
53 }
View Code 在Catalina中有个很重要的对象就是Server，先说明一下，在tomcat中实现Server接口的StandardServer对象，其中定义了socketServer,在此只作此说明，不展开介绍，在下一章中会专门对StandardServer类以及Server接口进行说明。
在start方法中首先需要判断是否初始化了实现server接口的类（以后都称作server类，不要误解Server为一个类），如果没有的话，那么调用load方法。
load方法中调用了一下几个方法：
initDirs：将Bootstrap中定义的catalina.home的值赋给CATALINA_BASE_PROP属性。以及对java.io.tmpdir属性的验证，下面是initDirs的代码实现：
1 protected void initDirs() {
2
3 String catalinaHome = System.getProperty(Globals.CATALINA_HOME_PROP);
4 if (catalinaHome == null) {
5 // Backwards compatibility patch for J2EE RI 1.3
6 String j2eeHome = System.getProperty("com.sun.enterprise.home");
7 if (j2eeHome != null) {
8 catalinaHome=System.getProperty("com.sun.enterprise.home");
9 } else if (System.getProperty(Globals.CATALINA_BASE_PROP) != null) {
10 catalinaHome = System.getProperty(Globals.CATALINA_BASE_PROP);
11 }
12 }
13 // last resort - for minimal/embedded cases.
14 if(catalinaHome==null) {
15 catalinaHome=System.getProperty("user.dir");
16 }
17 if (catalinaHome != null) {
18 File home = new File(catalinaHome);
19 if (!home.isAbsolute()) {
20 try {
21 catalinaHome = home.getCanonicalPath();
22 } catch (IOException e) {
23 catalinaHome = home.getAbsolutePath();
24 }
25 }
26 System.setProperty(Globals.CATALINA_HOME_PROP, catalinaHome);
27 }
28
29 if (System.getProperty(Globals.CATALINA_BASE_PROP) == null) {
30 System.setProperty(Globals.CATALINA_BASE_PROP,
31 catalinaHome);
32 } else {
33 String catalinaBase = System.getProperty(Globals.CATALINA_BASE_PROP);
34 File base = new File(catalinaBase);
35 if (!base.isAbsolute()) {
36 try {
37 catalinaBase = base.getCanonicalPath();
38 } catch (IOException e) {
39 catalinaBase = base.getAbsolutePath();
40 }
41 }
42 System.setProperty(Globals.CATALINA_BASE_PROP, catalinaBase);
43 }
44
45 String temp = System.getProperty("java.io.tmpdir");
46 if (temp == null || (!(new File(temp)).exists())
47 || (!(new File(temp)).isDirectory())) {
48 log.error(sm.getString("embedded.notmp", temp));
49 }
50
51 }
View Code 其中首先是兼容J2EE RI 1.3，获取com.sun.enterprise.home属性的值赋值给catalinaHome，如果不存在com.sun.enterprise.home这个属性，将Bootstrap中定义的catalina.home的值赋给CATALINA_BASE_PROP属性，如果以上都不成立，那么就是获取当前目录赋给CATALINA_BASE_PROP属性。其实当前目录也就是将Bootstrap中定义的catalina.home的值。只是在tomcat中进行了很繁琐的验证，当然这是有必要的。
createStartDigester：用来生成server.xml的操作，下面是代码实现：
1 protected Digester createStartDigester() {
2 long t1=System.currentTimeMillis();
3 // Initialize the digester
4 Digester digester = new Digester();
5 digester.setValidating(false);
6 digester.setRulesValidation(true);
7 HashMap<Class<?>, List<String>> fakeAttributes =
8 new HashMap<Class<?>, List<String>>();
9 ArrayList<String> attrs = new ArrayList<String>();
10 attrs.add("className");
11 fakeAttributes.put(Object.class, attrs);
12 digester.setFakeAttributes(fakeAttributes);
13 digester.setUseContextClassLoader(true);
14
15 // Configure the actions we will be using
16 digester.addObjectCreate("Server",
17 "org.apache.catalina.core.StandardServer",
18 "className");
19 digester.addSetProperties("Server");
20 digester.addSetNext("Server",
21 "setServer",
22 "org.apache.catalina.Server");
23
24 digester.addObjectCreate("Server/GlobalNamingResources",
25 "org.apache.catalina.deploy.NamingResources");
26 digester.addSetProperties("Server/GlobalNamingResources");
27 digester.addSetNext("Server/GlobalNamingResources",
28 "setGlobalNamingResources",
29 "org.apache.catalina.deploy.NamingResources");
30
31 digester.addObjectCreate("Server/Listener",
32 null, // MUST be specified in the element
33 "className");
34 digester.addSetProperties("Server/Listener");
35 digester.addSetNext("Server/Listener",
36 "addLifecycleListener",
37 "org.apache.catalina.LifecycleListener");
38
39 digester.addObjectCreate("Server/Service",
40 "org.apache.catalina.core.StandardService",
41 "className");
42 digester.addSetProperties("Server/Service");
43 digester.addSetNext("Server/Service",
44 "addService",
45 "org.apache.catalina.Service");
46
47 digester.addObjectCreate("Server/Service/Listener",
48 null, // MUST be specified in the element
49 "className");
50 digester.addSetProperties("Server/Service/Listener");
51 digester.addSetNext("Server/Service/Listener",
52 "addLifecycleListener",
53 "org.apache.catalina.LifecycleListener");
54
55 //Executor
56 digester.addObjectCreate("Server/Service/Executor",
57 "org.apache.catalina.core.StandardThreadExecutor",
58 "className");
59 digester.addSetProperties("Server/Service/Executor");
60
61 digester.addSetNext("Server/Service/Executor",
62 "addExecutor",
63 "org.apache.catalina.Executor");
64
65
66 digester.addRule("Server/Service/Connector",
67 new ConnectorCreateRule());
68 digester.addRule("Server/Service/Connector",
69 new SetAllPropertiesRule(new String[]{"executor"}));
70 digester.addSetNext("Server/Service/Connector",
71 "addConnector",
72 "org.apache.catalina.connector.Connector");
73
74
75 digester.addObjectCreate("Server/Service/Connector/Listener",
76 null, // MUST be specified in the element
77 "className");
78 digester.addSetProperties("Server/Service/Connector/Listener");
79 digester.addSetNext("Server/Service/Connector/Listener",
80 "addLifecycleListener",
81 "org.apache.catalina.LifecycleListener");
82
83 // Add RuleSets for nested elements
84 digester.addRuleSet(new NamingRuleSet("Server/GlobalNamingResources/"));
85 digester.addRuleSet(new EngineRuleSet("Server/Service/"));
86 digester.addRuleSet(new HostRuleSet("Server/Service/Engine/"));
87 digester.addRuleSet(new ContextRuleSet("Server/Service/Engine/Host/"));
88 addClusterRuleSet(digester, "Server/Service/Engine/Host/Cluster/");
89 digester.addRuleSet(new NamingRuleSet("Server/Service/Engine/Host/Context/"));
90
91 // When the 'engine' is found, set the parentClassLoader.
92 digester.addRule("Server/Service/Engine",
93 new SetParentClassLoaderRule(parentClassLoader));
94 addClusterRuleSet(digester, "Server/Service/Engine/Cluster/");
95
96 long t2=System.currentTimeMillis();
97 if (log.isDebugEnabled()) {
98 log.debug("Digester for server.xml created " + ( t2-t1 ));
99 }
100 return (digester);
101
102 }
View Code 在具体说明之前，我觉得有必要对Digester进行一下说明，以为可能有很多人和我一样，目前为止还还不是很清楚Digester为什么东西，其实他就是一个XML解析器，在这里就是构造一下tomcat启动时候的各种参数，各种初始化方法，初始化server，listener，connector，Executor等数据，我觉得这里有很多内容可以展开来说，所以我打算把他放到下一个章节专门对tomcat中Digester进行说明。在这里特别需要注意的就是如下这部分内容：
1 digester.addObjectCreate("Server",
2 "org.apache.catalina.core.StandardServer",
3 "className");
4 digester.addSetProperties("Server");
5 digester.addSetNext("Server",
6 "setServer",
7 "org.apache.catalina.Server");
8
9 digester.addObjectCreate("Server/GlobalNamingResources",
10 "org.apache.catalina.deploy.NamingResources");
11 digester.addSetProperties("Server/GlobalNamingResources");
12 digester.addSetNext("Server/GlobalNamingResources",
13 "setGlobalNamingResources",
14 "org.apache.catalina.deploy.NamingResources");
15
16 digester.addObjectCreate("Server/Listener",
17 null, // MUST be specified in the element
18 "className");
19 digester.addSetProperties("Server/Listener");
20 digester.addSetNext("Server/Listener",
21 "addLifecycleListener",
22 "org.apache.catalina.LifecycleListener");
23
24 digester.addObjectCreate("Server/Service",
25 "org.apache.catalina.core.StandardService",
26 "className");
27 digester.addSetProperties("Server/Service");
28 digester.addSetNext("Server/Service",
29 "addService",
30 "org.apache.catalina.Service");
31
32 digester.addObjectCreate("Server/Service/Listener",
33 null, // MUST be specified in the element
34 "className");
35 digester.addSetProperties("Server/Service/Listener");
36 digester.addSetNext("Server/Service/Listener",
37 "addLifecycleListener",
38 "org.apache.catalina.LifecycleListener");
39
40 //Executor
41 digester.addObjectCreate("Server/Service/Executor",
42 "org.apache.catalina.core.StandardThreadExecutor",
43 "className");
44 digester.addSetProperties("Server/Service/Executor");
45
46 digester.addSetNext("Server/Service/Executor",
47 "addExecutor",
48 "org.apache.catalina.Executor");
比如这里面的digester.addSetNext("Server","setServer","org.apache.catalina.Server")这句话,在Digester类中的实现如下：
1 public void addSetNext(String pattern, String methodName,
2 String paramType) {
3
4 addRule(pattern,
5 new SetNextRule(methodName, paramType));
6
7 }
实现的内容就是把org.apache.catalina.Server以及setServer以SetNextRule的类型保存起来。看一下SetNextRule对象提供的方法，
其中end方法的实现如下：
public void end(String namespace, String name) throws Exception {
// Identify the objects to be used
Object child = digester.peek(0);
Object parent = digester.peek(1);
if (digester.log.isDebugEnabled()) {
if (parent == null) {
digester.log.debug("[SetNextRule]{" + digester.match +
"} Call [NULL PARENT]." +
methodName + "(" + child + ")");
} else {
digester.log.debug("[SetNextRule]{" + digester.match +
"} Call " + parent.getClass().getName() + "." +
methodName + "(" + child + ")");
}
}
if(methodName.equals("setServer")){
System.out.println("111111111111111111");
}
// Call the specified method
IntrospectionUtils.callMethod1(parent, methodName,
child, paramType, digester.getClassLoader());
}
View Code 在这里通过反射实现的方法调用。大家可能困惑到底是在哪发出rule.end调用动作的呢？下面还是要看一下Digester类，igester继承了org.xml.sax.ext.DefaultHandler2类，其中有一个endElement方法，这个方法在读完XML中每个Element的时候执行，看一下endElement方法在Digester中的实现：
@Override
public void endElement(String namespaceURI, String localName,
String qName) throws SAXException {
boolean debug = log.isDebugEnabled();
if (debug) {
if (saxLog.isDebugEnabled()) {
saxLog.debug("endElement(" + namespaceURI + "," + localName +
"," + qName + ")");
}
log.debug(" match='" + match + "'");
log.debug(" bodyText='" + bodyText + "'");
}
// Parse system properties
bodyText = updateBodyText(bodyText);
// the actual element name is either in localName or qName, depending
// on whether the parser is namespace aware
String name = localName;
if ((name == null) || (name.length() < 1)) {
name = qName;
}
// Fire "body" events for all relevant rules
List<Rule> rules = matches.pop();
if ((rules != null) && (rules.size() > 0)) {
String bodyText = this.bodyText.toString();
for (int i = 0; i < rules.size(); i++) {
try {
Rule rule = rules.get(i);
if (debug) {
log.debug(" Fire body() for " + rule);
}
rule.body(namespaceURI, name, bodyText);
} catch (Exception e) {
log.error("Body event threw exception", e);
throw createSAXException(e);
} catch (Error e) {
log.error("Body event threw error", e);
throw e;
}
}
} else {
if (debug) {
log.debug(" No rules found matching '" + match + "'.");
}
if (rulesValidation) {
log.warn(" No rules found matching '" + match + "'.");
}
}
// Recover the body text from the surrounding element
bodyText = bodyTexts.pop();
if (debug) {
log.debug(" Popping body text '" + bodyText.toString() + "'");
}
// Fire "end" events for all relevant rules in reverse order
if (rules != null) {
for (int i = 0; i < rules.size(); i++) {
int j = (rules.size() - i) - 1;
try {
Rule rule = rules.get(j);
if (debug) {
log.debug(" Fire end() for " + rule);
}
if(name.equals("setServer")){
System.out.println("1222");
}
rule.end(namespaceURI, name);
} catch (Exception e) {
log.error("End event threw exception", e);
throw createSAXException(e);
} catch (Error e) {
log.error("End event threw error", e);
throw e;
}
}
}
// Recover the previous match expression
int slash = match.lastIndexOf('/');
if (slash >= 0) {
match = match.substring(0, slash);
} else {
match = "";
}
}
View Code 主要功能就是找出对应的rule来逐一调用rule.end方法。根据在Catalina.java类中digester添加的rule，就执行到了StandardServer类中的addService方法，设置的server对象，这部分内容很重要。
configFile：返回配置文件conf/server.xml文件。在获取配置文件conf/server.xml出错的时候，就尝试去获取server-embed.xml文件，如果都不存在，那么直接返回。记录日志。
initStreams：这个方法很简单只是做了一个tomcat自定义的流的重定向，
getServer().init：设置一下server的状态，然后初始化网络配置。
OK，load方法就说完了，很长。
然后在start方法中启动server。至于start方法，我们不再本文中说明，等在以后的章节会专门介绍Server。
然后在在当期运行环境中注册一个ShutdownHook，该钩子的作于就是当程序结束时候，将Catalina程序shutdown。
到此为止，start方法就算是说完了。其中主要内容就是如何构造一个server对象。在以后会展开说明Server对象。
Stop:另外一个被外部调用的方法就是stop方法，看一下stop方法的代码实现：
public void stop() {
try {
// Remove the ShutdownHook first so that server.stop()
// doesn't get invoked twice
if (useShutdownHook) {
Runtime.getRuntime().removeShutdownHook(shutdownHook);
// If JULI is being used, re-enable JULI's shutdown to ensure
// log messages are not lost
LogManager logManager = LogManager.getLogManager();
if (logManager instanceof ClassLoaderLogManager) {
((ClassLoaderLogManager) logManager).setUseShutdownHook(
true);
}
}
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
// This will fail on JDK 1.2. Ignoring, as Tomcat can run
// fine without the shutdown hook.
}
// Shut down the server
try {
Server s = getServer();
LifecycleState state = s.getState();
if (LifecycleState.STOPPING_PREP.compareTo(state) <= 0
&& LifecycleState.DESTROYED.compareTo(state) >= 0) {
// Nothing to do. stop() was already called
} else {
s.stop();
s.destroy();
}
} catch (LifecycleException e) {
log.error("Catalina.stop", e);
}
}
View Code 首先要移除在start方法中注册的钩子，否则在程序结束以后再次触发钩子中定义的事件，肯定会出错。然后就获取server对象，检查状态，如果在运行那么停止，然后将资源释放。stop方法简单很多。
stopServer:先检查Server对象是否存在，如果不存在就创建一个新的，然后关闭server以及Server中定义的socket。
Catalina中的内容大概就这么多了，很不过瘾的地方就是内容很多，没有办法全部展开，尤其是实现Server接口的Server对象，构建server的方法，希望在下面的章节中把如何通过Digester构建server，以及与次有很重要关系的Tomca的结构比如server,services,connector,container等说清楚。
如果有不正确的地方请指正。大家共同学习。 |
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