tomcat源码研究(1).doc

Tomcat源码研究作者：陈康作品：原创QQ:26237933Email:22tomcat启动过程分析（1）以tomcat为例，看tomcat是怎样启动的。tomcat中有一个startup.bat 批处理文件，这个文件会启动另一个批处理文件 catalina.bat 而这个批处理会设置set CLASSPATH=%CLASSPATH%;%CATALINA_HOME%binbootstrap.jar 也就是把bootstrap.jar所在目录加入classpath中，这样就可以通过jre来运行bootstrap.jar，我们看到在这个包中的 MANIFEST.MF的文件内容如下： Manifest-Version: 1.0Ant-Version: Apache Ant 1.6.5Created-By: 1.5.0_06-b05 (Sun Microsystems Inc.)Main-Class: org.apache.catalina.startup.BootstrapSpecification-Title: CatalinaSpecification-Version: 6.0Class-Path: commons-daemon.jar commons-logging-api.jar tomcat-juli.jar tomcat-coyote.jar 这里Main-Class: org.apache.catalina.startup.Bootstrap 指定了主函数所在的类，很显然，JVM通过这个文件找到 主函数，并进入这个类中的主函数入口执行。然后就一步步完成tomcat的启过程。tomcat启动批处理startup.batecho offif %OS% = Windows_NT setlocal /如果为window_nt系统，开始批处理文件中环境改动的本地化操作rem -rem Start script for the CATALINA Serverremrem $Id: startup.bat 467182 2006-10-23 23:47:06Z markt $rem -rem Guess CATALINA_HOME if not definedset CURRENT_DIR=%cd% /把环境变量CURRENT_DIR设置为当前批处理执行所在目录if not %CATALINA_HOME% = goto gotHome /如果CATALINA_HOME不等于，将路到跳到gotHome标志处set CATALINA_HOME=%CURRENT_DIR% /设置CATALINA_HOME等于当前批处理执行路径if exist %CATALINA_HOME%bincatalina.bat goto okHome /看catalina.bat文件是否存在，存在就转到okHome标志处，不存在向下执行。cd . /返回上一层目录set CATALINA_HOME=%cd% /设置CATALINA_HOME等于当前目录cd %CURRENT_DIR% /进入批处理执行所在目录:gotHomeif exist %CATALINA_HOME%bincatalina.bat goto okHome /查看catalina.bat是否存在，存在就转到okHome执行。echo The CATALINA_HOME environment variable is not defined correctly /不存在输出错误echo This environment variable is needed to run this programgoto end /输出错误后跳到最后结束批处理执行。:okHomeset EXECUTABLE=%CATALINA_HOME%bincatalina.bat /设置变量EXECUTABLE为catalina.bat所在的绝对路径rem Check that target executable existsif exist %EXECUTABLE% goto okExec /如果catalina.bat存在转到okExec执行。echo Cannot find %EXECUTABLE% /不存在输出错误信息并结束批处理执行。echo This file is needed to run this programgoto end:okExecrem Get remaining unshifted command line arguments and save them in theset CMD_LINE_ARGS= /设置变量CMD_LINE_ARGS:setArgsif %1= goto doneSetArgsset CMD_LINE_ARGS=%CMD_LINE_ARGS% %1shiftgoto setArgs:doneSetArgscall %EXECUTABLE% start %CMD_LINE_ARGS% /调用批处理catalina.bat，start 后应为参数。:end注：此批处理的作用主要是为了设置CATALINA_HOME，并找到catalina.bat执行。tomcat启动批处理catalina.batecho offif %OS% = Windows_NT setlocalrem -rem Start/Stop Script for the CATALINA Serverremrem Environment Variable Prequisitesremrem CATALINA_HOME May point at your Catalina build directory.remrem CATALINA_BASE (Optional) Base directory for resolving dynamic portionsrem of a Catalina installation. If not present, resolves torem the same directory that CATALINA_HOME points to.remrem CATALINA_OPTS (Optional) Java runtime options used when the start,rem stop, or run command is executed.remrem CATALINA_TMPDIR (Optional) Directory path location of temporary directoryrem the JVM should use (java.io.tmpdir). Defaults torem %CATALINA_BASE%temp.remrem JAVA_HOME Must point at your Java Development Kit installation.rem Required to run the with the debug argument.remrem JRE_HOME Must point at your Java Runtime installation.rem Defaults to JAVA_HOME if empty.remrem JAVA_OPTS (Optional) Java runtime options used when the start,rem stop, or run command is executed.remrem JSSE_HOME (Optional) May point at your Java Secure Sockets Extensionrem (JSSE) installation, whose JAR files will be added to therem system class path used to start Tomcat.remrem JPDA_TRANSPORT (Optional) JPDA transport used when the jpda startrem command is executed. The default is dt_shmem.remrem JPDA_ADDRESS (Optional) Java runtime options used when the jpda startrem command is executed. The default is jdbconn.remrem JPDA_SUSPEND (Optional) Java runtime options used when the jpda startrem command is executed. Specifies whether JVM should suspendrem execution immediately after startup. Default is n.remrem JPDA_OPTS (Optional) Java runtime options used when the jpda startrem command is executed. If used, JPDA_TRANSPORT, JPDA_ADDRESS,rem and JPDA_SUSPEND are ignored. Thus, all required jpdarem options MUST be specified. The default is:remrem -Xdebug -Xrunjdwp:transport=%JPDA_TRANSPORT%,rem address=%JPDA_ADDRESS%,server=y,suspend=%JPDA_SUSPEND%remrem $Id: catalina.bat 537518 2007-05-12 21:11:40Z markt $rem -rem Guess CATALINA_HOME if not definedset CURRENT_DIR=%cd% /设置当前所有目录if not %CATALINA_HOME% = goto gotHomeset CATALINA_HOME=%CURRENT_DIR% /设置CATALINA_HOME为当前目录if exist %CATALINA_HOME%bincatalina.bat goto okHomecd .set CATALINA_HOME=%cd%cd %CURRENT_DIR%:gotHomeif exist %CATALINA_HOME%bincatalina.bat goto okHomeecho The CATALINA_HOME environment variable is not defined correctlyecho This environment variable is needed to run this programgoto end:okHomerem Get standard environment variablesif exist %CATALINA_HOME%binsetenv.bat call %CATALINA_HOME%binsetenv.bat /setenv.bat是否存在，如果存在将执行。rem Get standard Java environment variablesif exist %CATALINA_HOME%binsetclasspath.bat goto okSetclasspath /如果setclasspath.bat存在转到标志okSetclasspathecho Cannot find %CATALINA_HOME%binsetclasspath.bat /如果不存在，将退出。echo This file is needed to run this programgoto end:okSetclasspathset BASEDIR=%CATALINA_HOME% /设置BASEDIR等于tomcat所在目录，也就是bin上层目录call %CATALINA_HOME%binsetclasspath.bat %1 /调用setclasspath.bat执行。if errorlevel 1 goto end /如果执行发生错误将退出。rem Add on extra jar files to CLASSPATHif %JSSE_HOME% = goto noJsse /如果JSSE_HOME不存为空，将转到标志noJsse处set CLASSPATH=%CLASSPATH%;%JSSE_HOME%libjcert.jar;%JSSE_HOME%libjnet.jar;%JSSE_HOME%libjsse.jar /设置classpath等于自己再加上后面的两个。:noJsseset CLASSPATH=%CLASSPATH%;%CATALINA_HOME%binbootstrap.jar /把bootstrap.jar加入classpath中if not %CATALINA_BASE% = goto gotBaseset CATALINA_BASE=%CATALINA_HOME%:gotBaseif not %CATALINA_TMPDIR% = goto gotTmpdirset CATALINA_TMPDIR=%CATALINA_BASE%temp:gotTmpdirif not exist %CATALINA_BASE%perties goto noJuliset JAVA_OPTS=%JAVA_OPTS% -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=%CATALINA_BASE%perties:noJulirem - Execute The Requested Command -echo Using CATALINA_BASE: %CATALINA_BASE%echo Using CATALINA_HOME: %CATALINA_HOME%echo Using CATALINA_TMPDIR: %CATALINA_TMPDIR%if %1 = debug goto use_jdkecho Using JRE_HOME: %JRE_HOME%goto java_dir_displayed:use_jdkecho Using JAVA_HOME: %JAVA_HOME%:java_dir_displayedset _EXECJAVA=%_RUNJAVA% /执行JAVAset MAINCLASS=org.apache.catalina.startup.Bootstrap /主方法类set ACTION=start /执行参数set SECURITY_POLICY_FILE=set DEBUG_OPTS=set JPDA=if not %1 = jpda goto noJpdaset JPDA=jpdaif not %JPDA_TRANSPORT% = goto gotJpdaTransportset JPDA_TRANSPORT=dt_shmem:gotJpdaTransportif not %JPDA_ADDRESS% = goto gotJpdaAddressset JPDA_ADDRESS=jdbconn:gotJpdaAddressif not %JPDA_SUSPEND% = goto gotJpdaSuspendset JPDA_SUSPEND=n:gotJpdaSuspendif not %JPDA_OPTS% = goto gotJpdaOptsset JPDA_OPTS=-Xdebug -Xrunjdwp:transport=%JPDA_TRANSPORT%,address=%JPDA_ADDRESS%,server=y,suspend=%JPDA_SUSPEND%:gotJpdaOptsshift:noJpdaif %1 = debug goto doDebugif %1 = run goto doRunif %1 = start goto doStartif %1 = stop goto doStopif %1 = version goto doVersionecho Usage: catalina ( commands . )echo commands:echo debug Start Catalina in a debuggerecho debug -security Debug Catalina with a security managerecho jpda start Start Catalina under JPDA debuggerecho run Start Catalina in the current windowecho run -security Start in the current window with security managerecho start Start Catalina in a separate windowecho start -security Start in a separate window with security managerecho stop Stop Catalinaecho version What version of tomcat are you running?goto end:doDebugshiftset _EXECJAVA=%_RUNJDB%set DEBUG_OPTS=-sourcepath %CATALINA_HOME%.javaif not %1 = -security goto execCmdshiftecho Using Security Managerset SECURITY_POLICY_FILE=%CATALINA_BASE%confcatalina.policygoto execCmd:doRunshiftif not %1 = -security goto execCmdshiftecho Using Security Managerset SECURITY_POLICY_FILE=%CATALINA_BASE%confcatalina.policygoto execCmd:doStartshiftif not %OS% = Windows_NT goto noTitleset _EXECJAVA=start Tomcat %_RUNJAVA%goto gotTitle:noTitleset _EXECJAVA=start %_RUNJAVA%:gotTitleif not %1 = -security goto execCmdshiftecho Using Security Managerset SECURITY_POLICY_FILE=%CATALINA_BASE%confcatalina.policygoto execCmd:doStopshiftset ACTION=stopgoto execCmd:doVersion%_EXECJAVA% -classpath %CATALINA_HOME%libcatalina.jar org.apache.catalina.util.ServerInfogoto end:execCmdrem Get remaining unshifted command line arguments and save them in theset CMD_LINE_ARGS=:setArgsif %1= goto doneSetArgsset CMD_LINE_ARGS=%CMD_LINE_ARGS% %1shiftgoto setArgs:doneSetArgs/以下是执行的启动命令。rem Execute Java with the applicable propertiesif not %JPDA% = goto doJpdaif not %SECURITY_POLICY_FILE% = goto doSecurity%_EXECJAVA% %JAVA_OPTS% %CATALINA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs=%JAVA_ENDORSED_DIRS% -classpath %CLASSPATH% -Dcatalina.base=%CATALINA_BASE% -Dcatalina.home=%CATALINA_HOME% -Djava.io.tmpdir=%CATALINA_TMPDIR% %MAINCLASS% %CMD_LINE_ARGS% %ACTION%goto end:doSecurity%_EXECJAVA% %JAVA_OPTS% %CATALINA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs=%JAVA_ENDORSED_DIRS% -classpath %CLASSPATH% -Djava.security.manager -Djava.security.policy=%SECURITY_POLICY_FILE% -Dcatalina.base=%CATALINA_BASE% -Dcatalina.home=%CATALINA_HOME% -Djava.io.tmpdir=%CATALINA_TMPDIR% %MAINCLASS% %CMD_LINE_ARGS% %ACTION%goto end:doJpdaif not %SECURITY_POLICY_FILE% = goto doSecurityJpda%_EXECJAVA% %JAVA_OPTS% %CATALINA_OPTS% %JPDA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs=%JAVA_ENDORSED_DIRS% -classpath %CLASSPATH% -Dcatalina.base=%CATALINA_BASE% -Dcatalina.home=%CATALINA_HOME% -Djava.io.tmpdir=%CATALINA_TMPDIR% %MAINCLASS% %CMD_LINE_ARGS% %ACTION%goto end:doSecurityJpda%_EXECJAVA% %JAVA_OPTS% %CATALINA_OPTS% %JPDA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs=%JAVA_ENDORSED_DIRS% -classpath %CLASSPATH% -Djava.security.manager -Djava.security.policy=%SECURITY_POLICY_FILE% -Dcatalina.base=%CATALINA_BASE% -Dcatalina.home=%CATALINA_HOME% -Djava.io.tmpdir=%CATALINA_TMPDIR% %MAINCLASS% %CMD_LINE_ARGS% %ACTION%goto end:endtomcat启动批处理setclasspath.batrem -rem Set CLASSPATH and Java optionsremrem $Id: setclasspath.bat 545668 2007-06-09 00:18:22Z markt $rem -rem Make sure prerequisite environment variables are setif not %JAVA_HOME% = goto gotJdkHomeif not %JRE_HOME% = goto gotJreHomeecho Neither the JAVA_HOME nor the JRE_HOME environment variable is definedecho At least one of these environment variable is needed to run this programgoto exit:gotJreHomeif not exist %JRE_HOME%binjava.exe goto noJavaHomeif not exist %JRE_HOME%binjavaw.exe goto noJavaHomeif not %1 = debug goto okJavaHomeecho JAVA_HOME should point to a JDK in order to run in debug mode.goto exit:gotJdkHomeif not exist %JAVA_HOME%binjava.exe goto noJavaHomeif not exist %JAVA_HOME%binjavaw.exe goto noJavaHomeif not exist %JAVA_HOME%binjdb.exe goto noJavaHomeif not exist %JAVA_HOME%binjavac.exe goto noJavaHomeif not %JRE_HOME% = goto okJavaHomeset JRE_HOME=%JAVA_HOME%goto okJavaHome:noJavaHomeecho The JAVA_HOME environment variable is not defined correctlyecho This environment variable is needed to run this programecho NB: JAVA_HOME should point to a JDK not a JREgoto exit:okJavaHomeif not %BASEDIR% = goto gotBasedirecho The BASEDIR environment variable is not definedecho This environment variable is needed to run this programgoto exit:gotBasedirif exist %BASEDIR%binsetclasspath.bat goto okBasedirecho The BASEDIR environment variable is not defined correctlyecho This environment variable is needed to run this programgoto exit:okBasedirrem Set the default -Djava.endorsed.dirs argumentset JAVA_ENDORSED_DIRS=%BASEDIR%endorsedrem Set standard CLASSPATHrem Note that there are no quotes as we do not want to introduce randomrem quotes into the CLASSPATHif not exist %JAVA_HOME%libtools.jar goto noJavacset CLASSPATH=%JAVA_HOME%libtools.jar:noJavacrem Set standard command for invoking Java.rem Note that NT requires a window name argument when using start.rem Also note the quoting as JAVA_HOME may contain spaces.set _RUNJAVA=%JRE_HOME%binjavaset _RUNJAVAW=%JRE_HOME%binjavawset _RUNJDB=%JAVA_HOME%binjdbset _RUNJAVAC=%JAVA_HOME%binjavacgoto end:exitexit /b 1:endtomcat批处理最后执行命令D:apache-tomcat-6.0.14binstartup.batUsing CATALINA_BASE: D:apache-tomcat-6.0.14Using CATALINA_HOME: D:apache-tomcat-6.0.14Using CATALINA_TMPDIR: D:apache-tomcat-6.0.14tempUsing JRE_HOME: C:Javajdk1.5.0_16start Tomcat C:Javajdk1.5.0_16binjava -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=D:perties -Djava.endorsed.dirs=D:apache-tomcat-6.0.14endorsed -classpath C:Javajdk1.5.0_16libtools.jar;D:apache-tomcat-6.0.14binbootstrap.jar -Dcatalina.base=D:apache-tomcat-6.0.14 -Dcatalina.home=D:apache-tomcat-6.0.14 -Djava.io.tmpdir=D:apache-tomcat-6.0.14temp org.apache.catalina.startup.Bootstrap start注：从中我们可以看到，其实启动tomcat就是一个 java -D -classpth org.apache.catalina.startup.Bootstrap start过程，设置资源，设置classpath，然后启动org.apache.catalina.startup.Bootstrap这个类的主方法main方法，带参数starttomcat原码目录结构及说明1)org.apache.catalina.startup :启动相关的一类.2)org.apache.catalina :tomcat的核心接口3)org.apache.catalina.core :tomcat的核心接口实现类.tomcat(1)之Bootstrap.java此类的作用,就是 * Initialize daemon. 初始化 * 主要有以下过程 * 1)设置环境变量,初始化类加载器,事实上就是为commonLoader,catalinaLoader,sharedLoader,不过这里其实都为 * commonLoader,因为其它几个并没配置,配置文件位于 org.apache,catalina.startup中的perties。 common.loader=$catalina.home/lib,$catalina.home/lib/*.jar server.loader= shared.loader= * 2)设置当前线程当前类加载器,也是commonLoader,其实commonLoader就是批向tomcat/lib中的一个加载器. 也是tomcat的核心类库的加载位置，相然用的一些包也可以放在这个目录，同样可以被tomcat默认加载器 加载。 * 3)加载org.apache.catalina.startup.Catalina,并设置父加载器为commonLoader,最后把实例附值给catalinaDaemon 通过反射方式得到Catalina实例，同时设置Catalina的一个属性（也就是父加载器）为：commonLoader 然后把实例传给属性catalinaDaemon，其它方法通这个实例来操作类Catalina的实例。 * 初始化完成. * 从这个初始化来看,只处理两个方面,1)设置加载器 2)产生Catalina实例 * 然后如一些start,load,stop都是调用类Catalina中相应方法来完成.(利用反射的方式) 我们看批处理最后执行的命令为：.apache.catalina.startup.Bootstrap start,显然带的参数是start. 在启动时主要执行Catalina实例的二个方法： 1)load 2)start 源码： daemon.load(args); /加载参数，这里args为main方法中的参数，从最后批处理执行来看，只一个参数start,因此 /args中只有一个元素的数组，这个元素值为:start daemon.start(); 我们来看看方法Bootstrap中的load做了什么事。 - /* * Load daemon. */ private void load(String arguments) throws Exception / Call the load() method String methodName = load; Object param; /定义参数 Class paramTypes; /定义方法参数类型 if (arguments=null | arguments.length=0) paramTypes = null; param = null; else paramTypes = new Class1; paramTypes0 = arguments.getClass(); param = new Object1; param0 = arguments; Method method = catalinaDaemon.getClass().getMethod(methodName, paramTypes); if (log.isDebugEnabled() log.debug(Calling startup class + method); method.invoke(catalinaDaemon, param); 注：从原码看得出来，这个