Tomcat源码 - 1. 目录结构与配置文件 - 在码圈-专注编程技术分享-代码改变未来，努力coding

简介

Tomcat是Apache 软件基金会（Apache Software Foundation）的Jakarta 项目中的一个核心项目，由Apache、Sun 和其他一些公司及个人共同开发而成。

Tomcat 服务器是一个免费的开放源代码的Web 应用服务器，属于轻量级应用服务器，在中小型系统和并发访问用户不是很多的场合下被普遍使用，是开发和调试JSP 程序的首选。

Tomcat 8.5
官网地址 https://tomcat.apache.org/
文档地址 https://tomcat.apache.org/tomcat-8.5-doc/introduction.html

什么是Tomcat？

The Apache Tomcat® software is an open source implementation of the Jakarta Servlet, Jakarta Server Pages, Jakarta Expression Language, Jakarta WebSocket, Jakarta Annotations and Jakarta Authentication specifications. The Jakarta EE platform is the evolution of the Java EE platform. Tomcat 10 and later implement specifications developed as part of Jakarta EE. Tomcat 9 and earlier implement specifications developed as part of Java EE

Tomcat是属于Apache基金会，它是一个开源软件，软件实现了Jakarta Servlet, Jakarta Server Pages, Jakarta Expression Language, Jakarta WebSocket, Jakarta Annotations and Jakarta Authentication 等规范。

Tomcat是一个容器，用于承载Servlet，那么我们说Tomcat就是一个实现了部分J2EE规范的服务器。J2 EE和Jakarta EE（Eclipse基金会）这两是啥？用于Tomcat10以后都是Jakarta EE，而9之前就是J2EE，那么研究源码版本：8.x即可。

什么是规范？

Java 是一门语言，那么语言是不是需要依赖第三方对于他们自己的产品实现，以一种jar包的方式提供给我们直接调用，那么这个jar包称之为：SDK（Software Development Kit）。那么问题来了？若以数据库操作举例，现在的数据库有：DB2、ORACLE、MYSQL.....诸多数据库，so？如果没有一个规范，那么每个开发商自己定义一些自己的写法，就代表了你每换一个数据库，你就要重新编写代码。那么以动态服务器为例：JBOSS、Tomcat、WebLogic.....假如没有一个规范，那么还是那句话，更换一个服务器你就重新写一遍代码。这种是不能够忍受的。这时候就需要有人出来搞规范。用于约束第三方如何实现，来提供一个统一的上层接口即可。所以，总结一下：规范在java层面就是面向接口编程。

核心术语

根据Tomcat 8.5 的文档描述
Context - In a nutshell, a Context is a web application. (一个上下文就是一个Web应用)

文件夹和文件

These are some of the key tomcat directories:

/bin - Startup, shutdown, and other scripts. The *.sh files (for Unix systems) are functional duplicates of the *.bat files (for Windows systems). Since the Win32 command-line lacks certain functionality, there are some additional files in here. binary 二进制，执行文件，大部分都是脚本，脚本分为：windows（bat）、linux（sh）
/conf - Configuration files and related DTDs. The most important file in here is server.xml. It is the main configuration file for the container. configuration 配置文件
/logs - Log files are here by default. 日志
/webapps - This is where your webapps go. 这里放你的web应用

Tomcat的脚本文件

启动脚本 `startup.sh`

#!/bin/sh
os400=false
case "`uname`" in
OS400*) os400=true;;
esac
PRG="$0"

while [ -h "$PRG" ] ; do
  ls=`ls -ld "$PRG"`
  link=`expr "$ls" : '.*-> \(.*\)$'`
  if expr "$link" : '/.*' > /dev/null; then
    PRG="$link"
  else
    PRG=`dirname "$PRG"`/"$link"
  fi
done

PRGDIR=`dirname "$PRG"`
EXECUTABLE=catalina.sh

if $os400; then
  eval
else
  if [ ! -x "$PRGDIR"/"$EXECUTABLE" ]; then
    echo "Cannot find $PRGDIR/$EXECUTABLE"
    echo "The file is absent or does not have execute permission"
    echo "This file is needed to run this program"
    exit 1
  fi
fi

exec "$PRGDIR"/"$EXECUTABLE" start "$@"

得出结论最终调用 EXECUTABLE=catalina.sh 执行 start

核心脚本 `catalina.sh`

直接调用了org.apache.catalina.startup.Bootstrap类（类的全限定名：包名+类名，因为这里Bootstrap翻译成中文叫做启动、初始化的意思，所以这里可能和前端的Bootstrap框架产生了同名） start方法完成了启动。

#!/bin/sh

# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# -----------------------------------------------------------------------------
# Control Script for the CATALINA Server
#
# For supported commands call "catalina.sh help" or see the usage section at
# the end of this file.
#
# Environment Variable Prerequisites
#
#   Do not set the variables in this script. Instead put them into a script
#   setenv.sh in CATALINA_BASE/bin to keep your customizations separate.
#
#   CATALINA_HOME   May point at your Catalina "build" directory.
#
#   CATALINA_BASE   (Optional) Base directory for resolving dynamic portions
#                   of a Catalina installation.  If not present, resolves to
#                   the same directory that CATALINA_HOME points to.
#
#   CATALINA_OUT    (Optional) Full path to a file where stdout and stderr
#                   will be redirected.
#                   Default is $CATALINA_BASE/logs/catalina.out
#
#   CATALINA_OUT_CMD (Optional) Command which will be executed and receive
#                   as its stdin the stdout and stderr from the Tomcat java
#                   process. If CATALINA_OUT_CMD is set, the value of
#                   CATALINA_OUT will be used as a named pipe.
#                   No default.
#                   Example (all one line)
#                   CATALINA_OUT_CMD="/usr/bin/rotatelogs -f $CATALINA_BASE/logs/catalina.out.%Y-%m-%d.log 86400"
#
#   CATALINA_OPTS   (Optional) Java runtime options used when the "start",
#                   "run" or "debug" command is executed.
#                   Include here and not in JAVA_OPTS all options, that should
#                   only be used by Tomcat itself, not by the stop process,
#                   the version command etc.
#                   Examples are heap size, GC logging, JMX ports etc.
#
#   CATALINA_TMPDIR (Optional) Directory path location of temporary directory
#                   the JVM should use (java.io.tmpdir).  Defaults to
#                   $CATALINA_BASE/temp.
#
#   JAVA_HOME       Must point at your Java Development Kit installation.
#                   Required to run the with the "debug" argument.
#
#   JRE_HOME        Must point at your Java Runtime installation.
#                   Defaults to JAVA_HOME if empty. If JRE_HOME and JAVA_HOME
#                   are both set, JRE_HOME is used.
#
#   JAVA_OPTS       (Optional) Java runtime options used when any command
#                   is executed.
#                   Include here and not in CATALINA_OPTS all options, that
#                   should be used by Tomcat and also by the stop process,
#                   the version command etc.
#                   Most options should go into CATALINA_OPTS.
#
#   JAVA_ENDORSED_DIRS (Optional) Lists of of colon separated directories
#                   containing some jars in order to allow replacement of APIs
#                   created outside of the JCP (i.e. DOM and SAX from W3C).
#                   It can also be used to update the XML parser implementation.
#                   This is only supported for Java <= 8.
#                   Defaults to $CATALINA_HOME/endorsed.
#
#   JPDA_TRANSPORT  (Optional) JPDA transport used when the "jpda start"
#                   command is executed. The default is "dt_socket".
#
#   JPDA_ADDRESS    (Optional) Java runtime options used when the "jpda start"
#                   command is executed. The default is localhost:8000.
#
#   JPDA_SUSPEND    (Optional) Java runtime options used when the "jpda start"
#                   command is executed. Specifies whether JVM should suspend
#                   execution immediately after startup. Default is "n".
#
#   JPDA_OPTS       (Optional) Java runtime options used when the "jpda start"
#                   command is executed. If used, JPDA_TRANSPORT, JPDA_ADDRESS,
#                   and JPDA_SUSPEND are ignored. Thus, all required jpda
#                   options MUST be specified. The default is:
#
#                   -agentlib:jdwp=transport=$JPDA_TRANSPORT,
#                       address=$JPDA_ADDRESS,server=y,suspend=$JPDA_SUSPEND
#
#   JSSE_OPTS       (Optional) Java runtime options used to control the TLS
#                   implementation when JSSE is used. Default is:
#                   "-Djdk.tls.ephemeralDHKeySize=2048"
#
#   CATALINA_PID    (Optional) Path of the file which should contains the pid
#                   of the catalina startup java process, when start (fork) is
#                   used
#
#   CATALINA_LOGGING_CONFIG (Optional) Override Tomcat's logging config file
#                   Example (all one line)
#                   CATALINA_LOGGING_CONFIG="-Djava.util.logging.config.file=$CATALINA_BASE/conf/logging.properties"
#
#   LOGGING_CONFIG  Deprecated
#                   Use CATALINA_LOGGING_CONFIG
#                   This is only used if CATALINA_LOGGING_CONFIG is not set
#                   and LOGGING_CONFIG starts with "-D..."
#
#   LOGGING_MANAGER (Optional) Override Tomcat's logging manager
#                   Example (all one line)
#                   LOGGING_MANAGER="-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager"
#
#   UMASK           (Optional) Override Tomcat's default UMASK of 0027
#
#   USE_NOHUP       (Optional) If set to the string true the start command will
#                   use nohup so that the Tomcat process will ignore any hangup
#                   signals. Default is "false" unless running on HP-UX in which
#                   case the default is "true"
# -----------------------------------------------------------------------------

# OS specific support.  $var _must_ be set to either true or false.
cygwin=false
darwin=false
os400=false
hpux=false
case "`uname`" in
CYGWIN*) cygwin=true;;
Darwin*) darwin=true;;
OS400*) os400=true;;
HP-UX*) hpux=true;;
esac

# resolve links - $0 may be a softlink
PRG="$0"

while [ -h "$PRG" ]; do
  ls=`ls -ld "$PRG"`
  link=`expr "$ls" : '.*-> \(.*\)$'`
  if expr "$link" : '/.*' > /dev/null; then
    PRG="$link"
  else
    PRG=`dirname "$PRG"`/"$link"
  fi
done

# Get standard environment variables
PRGDIR=`dirname "$PRG"`

# Only set CATALINA_HOME if not already set
[ -z "$CATALINA_HOME" ] && CATALINA_HOME=`cd "$PRGDIR/.." >/dev/null; pwd`

# Copy CATALINA_BASE from CATALINA_HOME if not already set
[ -z "$CATALINA_BASE" ] && CATALINA_BASE="$CATALINA_HOME"

# Ensure that any user defined CLASSPATH variables are not used on startup,
# but allow them to be specified in setenv.sh, in rare case when it is needed.
CLASSPATH=

if [ -r "$CATALINA_BASE/bin/setenv.sh" ]; then
  . "$CATALINA_BASE/bin/setenv.sh"
elif [ -r "$CATALINA_HOME/bin/setenv.sh" ]; then
  . "$CATALINA_HOME/bin/setenv.sh"
fi

# For Cygwin, ensure paths are in UNIX format before anything is touched
if $cygwin; then
  [ -n "$JAVA_HOME" ] && JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
  [ -n "$JRE_HOME" ] && JRE_HOME=`cygpath --unix "$JRE_HOME"`
  [ -n "$CATALINA_HOME" ] && CATALINA_HOME=`cygpath --unix "$CATALINA_HOME"`
  [ -n "$CATALINA_BASE" ] && CATALINA_BASE=`cygpath --unix "$CATALINA_BASE"`
  [ -n "$CLASSPATH" ] && CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
fi

# Ensure that neither CATALINA_HOME nor CATALINA_BASE contains a colon
# as this is used as the separator in the classpath and Java provides no
# mechanism for escaping if the same character appears in the path.
case $CATALINA_HOME in
  *:*) echo "Using CATALINA_HOME:   $CATALINA_HOME";
       echo "Unable to start as CATALINA_HOME contains a colon (:) character";
       exit 1;
esac
case $CATALINA_BASE in
  *:*) echo "Using CATALINA_BASE:   $CATALINA_BASE";
       echo "Unable to start as CATALINA_BASE contains a colon (:) character";
       exit 1;
esac

# For OS400
if $os400; then
  # Set job priority to standard for interactive (interactive - 6) by using
  # the interactive priority - 6, the helper threads that respond to requests
  # will be running at the same priority as interactive jobs.
  COMMAND='chgjob job('$JOBNAME') runpty(6)'
  system $COMMAND

  # Enable multi threading
  export QIBM_MULTI_THREADED=Y
fi

# Get standard Java environment variables
if $os400; then
  # -r will Only work on the os400 if the files are:
  # 1. owned by the user
  # 2. owned by the PRIMARY group of the user
  # this will not work if the user belongs in secondary groups
  . "$CATALINA_HOME"/bin/setclasspath.sh
else
  if [ -r "$CATALINA_HOME"/bin/setclasspath.sh ]; then
    . "$CATALINA_HOME"/bin/setclasspath.sh
  else
    echo "Cannot find $CATALINA_HOME/bin/setclasspath.sh"
    echo "This file is needed to run this program"
    exit 1
  fi
fi

# Add on extra jar files to CLASSPATH
if [ ! -z "$CLASSPATH" ] ; then
  CLASSPATH="$CLASSPATH":
fi
CLASSPATH="$CLASSPATH""$CATALINA_HOME"/bin/bootstrap.jar

if [ -z "$CATALINA_OUT" ] ; then
  CATALINA_OUT="$CATALINA_BASE"/logs/catalina.out
fi

if [ -z "$CATALINA_TMPDIR" ] ; then
  # Define the java.io.tmpdir to use for Catalina
  CATALINA_TMPDIR="$CATALINA_BASE"/temp
fi

# Add tomcat-juli.jar to classpath
# tomcat-juli.jar can be over-ridden per instance
if [ -r "$CATALINA_BASE/bin/tomcat-juli.jar" ] ; then
  CLASSPATH=$CLASSPATH:$CATALINA_BASE/bin/tomcat-juli.jar
else
  CLASSPATH=$CLASSPATH:$CATALINA_HOME/bin/tomcat-juli.jar
fi

# Bugzilla 37848: When no TTY is available, don't output to console
have_tty=0
if [ -t 0 ]; then
    have_tty=1
fi

# For Cygwin, switch paths to Windows format before running java
if $cygwin; then
  JAVA_HOME=`cygpath --absolute --windows "$JAVA_HOME"`
  JRE_HOME=`cygpath --absolute --windows "$JRE_HOME"`
  CATALINA_HOME=`cygpath --absolute --windows "$CATALINA_HOME"`
  CATALINA_BASE=`cygpath --absolute --windows "$CATALINA_BASE"`
  CATALINA_TMPDIR=`cygpath --absolute --windows "$CATALINA_TMPDIR"`
  CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
  [ -n "$JAVA_ENDORSED_DIRS" ] && JAVA_ENDORSED_DIRS=`cygpath --path --windows "$JAVA_ENDORSED_DIRS"`
fi

if [ -z "$JSSE_OPTS" ] ; then
  JSSE_OPTS="-Djdk.tls.ephemeralDHKeySize=2048"
fi
JAVA_OPTS="$JAVA_OPTS $JSSE_OPTS"

# Register custom URL handlers
# Do this here so custom URL handles (specifically 'war:...') can be used in the security policy
JAVA_OPTS="$JAVA_OPTS -Djava.protocol.handler.pkgs=org.apache.catalina.webresources"

# Check for the deprecated LOGGING_CONFIG
# Only use it if CATALINA_LOGGING_CONFIG is not set and LOGGING_CONFIG starts with "-D..."
if [ -z "$CATALINA_LOGGING_CONFIG" ]; then
  case $LOGGING_CONFIG in
    -D*) CATALINA_LOGGING_CONFIG="$LOGGING_CONFIG"
  esac
fi

# Set juli LogManager config file if it is present and an override has not been issued
if [ -z "$CATALINA_LOGGING_CONFIG" ]; then
  if [ -r "$CATALINA_BASE"/conf/logging.properties ]; then
    CATALINA_LOGGING_CONFIG="-Djava.util.logging.config.file=$CATALINA_BASE/conf/logging.properties"
  else
    # Bugzilla 45585
    CATALINA_LOGGING_CONFIG="-Dnop"
  fi
fi

if [ -z "$LOGGING_MANAGER" ]; then
  LOGGING_MANAGER="-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager"
fi

# Set UMASK unless it has been overridden
if [ -z "$UMASK" ]; then
    UMASK="0027"
fi
umask $UMASK

# Java 9 no longer supports the java.endorsed.dirs
# system property. Only try to use it if
# JAVA_ENDORSED_DIRS was explicitly set
# or CATALINA_HOME/endorsed exists.
ENDORSED_PROP=ignore.endorsed.dirs
if [ -n "$JAVA_ENDORSED_DIRS" ]; then
    ENDORSED_PROP=java.endorsed.dirs
fi
if [ -d "$CATALINA_HOME/endorsed" ]; then
    ENDORSED_PROP=java.endorsed.dirs
fi

# Make the umask available when using the org.apache.catalina.security.SecurityListener
JAVA_OPTS="$JAVA_OPTS -Dorg.apache.catalina.security.SecurityListener.UMASK=`umask`"

if [ -z "$USE_NOHUP" ]; then
    if $hpux; then
        USE_NOHUP="true"
    else
        USE_NOHUP="false"
    fi
fi
unset _NOHUP
if [ "$USE_NOHUP" = "true" ]; then
    _NOHUP="nohup"
fi

# Add the JAVA 9 specific start-up parameters required by Tomcat
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.base/java.lang=ALL-UNNAMED"
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.base/java.io=ALL-UNNAMED"
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.base/java.util=ALL-UNNAMED"
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.base/java.util.concurrent=ALL-UNNAMED"
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.rmi/sun.rmi.transport=ALL-UNNAMED"
export JDK_JAVA_OPTIONS

# ----- Execute The Requested Command -----------------------------------------

# Bugzilla 37848: only output this if we have a TTY
if [ $have_tty -eq 1 ]; then
  echo "Using CATALINA_BASE:   $CATALINA_BASE"
  echo "Using CATALINA_HOME:   $CATALINA_HOME"
  echo "Using CATALINA_TMPDIR: $CATALINA_TMPDIR"
  if [ "$1" = "debug" ] ; then
    echo "Using JAVA_HOME:       $JAVA_HOME"
  else
    echo "Using JRE_HOME:        $JRE_HOME"
  fi
  echo "Using CLASSPATH:       $CLASSPATH"
  echo "Using CATALINA_OPTS:   $CATALINA_OPTS"
  if [ ! -z "$CATALINA_PID" ]; then
    echo "Using CATALINA_PID:    $CATALINA_PID"
  fi
fi

if [ "$1" = "jpda" ] ; then
  if [ -z "$JPDA_TRANSPORT" ]; then
    JPDA_TRANSPORT="dt_socket"
  fi
  if [ -z "$JPDA_ADDRESS" ]; then
    JPDA_ADDRESS="localhost:8000"
  fi
  if [ -z "$JPDA_SUSPEND" ]; then
    JPDA_SUSPEND="n"
  fi
  if [ -z "$JPDA_OPTS" ]; then
    JPDA_OPTS="-agentlib:jdwp=transport=$JPDA_TRANSPORT,address=$JPDA_ADDRESS,server=y,suspend=$JPDA_SUSPEND"
  fi
  CATALINA_OPTS="$JPDA_OPTS $CATALINA_OPTS"
  shift
fi

if [ "$1" = "debug" ] ; then
  if $os400; then
    echo "Debug command not available on OS400"
    exit 1
  else
    shift
    if [ "$1" = "-security" ] ; then
      if [ $have_tty -eq 1 ]; then
        echo "Using Security Manager"
      fi
      shift
      eval exec "\"$_RUNJDB\"" "\"$CATALINA_LOGGING_CONFIG\"" $LOGGING_MANAGER "$JAVA_OPTS" "$CATALINA_OPTS" \
        -D$ENDORSED_PROP="$JAVA_ENDORSED_DIRS" \
        -classpath "$CLASSPATH" \
        -sourcepath "$CATALINA_HOME"/../../java \
        -Djava.security.manager \
        -Djava.security.policy=="$CATALINA_BASE"/conf/catalina.policy \
        -Dcatalina.base="$CATALINA_BASE" \
        -Dcatalina.home="$CATALINA_HOME" \
        -Djava.io.tmpdir="$CATALINA_TMPDIR" \
        org.apache.catalina.startup.Bootstrap "$@" start
    else
      eval exec "\"$_RUNJDB\"" "\"$CATALINA_LOGGING_CONFIG\"" $LOGGING_MANAGER "$JAVA_OPTS" "$CATALINA_OPTS" \
        -D$ENDORSED_PROP="$JAVA_ENDORSED_DIRS" \
        -classpath "$CLASSPATH" \
        -sourcepath "$CATALINA_HOME"/../../java \
        -Dcatalina.base="$CATALINA_BASE" \
        -Dcatalina.home="$CATALINA_HOME" \
        -Djava.io.tmpdir="$CATALINA_TMPDIR" \
        org.apache.catalina.startup.Bootstrap "$@" start
    fi
  fi

elif [ "$1" = "run" ]; then

  shift
  if [ "$1" = "-security" ] ; then
    if [ $have_tty -eq 1 ]; then
      echo "Using Security Manager"
    fi
    shift
    eval exec "\"$_RUNJAVA\"" "\"$CATALINA_LOGGING_CONFIG\"" $LOGGING_MANAGER "$JAVA_OPTS" "$CATALINA_OPTS" \
      -D$ENDORSED_PROP="\"$JAVA_ENDORSED_DIRS\"" \
      -classpath "\"$CLASSPATH\"" \
      -Djava.security.manager \
      -Djava.security.policy=="\"$CATALINA_BASE/conf/catalina.policy\"" \
      -Dcatalina.base="\"$CATALINA_BASE\"" \
      -Dcatalina.home="\"$CATALINA_HOME\"" \
      -Djava.io.tmpdir="\"$CATALINA_TMPDIR\"" \
      org.apache.catalina.startup.Bootstrap "$@" start
  else
    eval exec "\"$_RUNJAVA\"" "\"$CATALINA_LOGGING_CONFIG\"" $LOGGING_MANAGER "$JAVA_OPTS" "$CATALINA_OPTS" \
      -D$ENDORSED_PROP="\"$JAVA_ENDORSED_DIRS\"" \
      -classpath "\"$CLASSPATH\"" \
      -Dcatalina.base="\"$CATALINA_BASE\"" \
      -Dcatalina.home="\"$CATALINA_HOME\"" \
      -Djava.io.tmpdir="\"$CATALINA_TMPDIR\"" \
      org.apache.catalina.startup.Bootstrap "$@" start
  fi

elif [ "$1" = "start" ] ; then

  if [ ! -z "$CATALINA_PID" ]; then
    if [ -f "$CATALINA_PID" ]; then
      if [ -s "$CATALINA_PID" ]; then
        echo "Existing PID file found during start."
        if [ -r "$CATALINA_PID" ]; then
          PID=`cat "$CATALINA_PID"`
          ps -p $PID >/dev/null 2>&1
          if [ $? -eq 0 ] ; then
            echo "Tomcat appears to still be running with PID $PID. Start aborted."
            echo "If the following process is not a Tomcat process, remove the PID file and try again:"
            ps -f -p $PID
            exit 1
          else
            echo "Removing/clearing stale PID file."
            rm -f "$CATALINA_PID" >/dev/null 2>&1
            if [ $? != 0 ]; then
              if [ -w "$CATALINA_PID" ]; then
                cat /dev/null > "$CATALINA_PID"
              else
                echo "Unable to remove or clear stale PID file. Start aborted."
                exit 1
              fi
            fi
          fi
        else
          echo "Unable to read PID file. Start aborted."
          exit 1
        fi
      else
        rm -f "$CATALINA_PID" >/dev/null 2>&1
        if [ $? != 0 ]; then
          if [ ! -w "$CATALINA_PID" ]; then
            echo "Unable to remove or write to empty PID file. Start aborted."
            exit 1
          fi
        fi
      fi
    fi
  fi

  shift
  if [ -z "$CATALINA_OUT_CMD" ] ; then
    touch "$CATALINA_OUT"
  else
    if [ ! -e "$CATALINA_OUT" ]; then
      if ! mkfifo "$CATALINA_OUT"; then
        echo "cannot create named pipe $CATALINA_OUT. Start aborted."
        exit 1
      fi
    elif [ ! -p "$CATALINA_OUT" ]; then
      echo "$CATALINA_OUT exists and is not a named pipe. Start aborted."
      exit 1
    fi
    $CATALINA_OUT_CMD <"$CATALINA_OUT" &
  fi
  if [ "$1" = "-security" ] ; then
    if [ $have_tty -eq 1 ]; then
      echo "Using Security Manager"
    fi
    shift
    eval $_NOHUP "\"$_RUNJAVA\"" "\"$CATALINA_LOGGING_CONFIG\"" $LOGGING_MANAGER "$JAVA_OPTS" "$CATALINA_OPTS" \
      -D$ENDORSED_PROP="\"$JAVA_ENDORSED_DIRS\"" \
      -classpath "\"$CLASSPATH\"" \
      -Djava.security.manager \
      -Djava.security.policy=="\"$CATALINA_BASE/conf/catalina.policy\"" \
      -Dcatalina.base="\"$CATALINA_BASE\"" \
      -Dcatalina.home="\"$CATALINA_HOME\"" \
      -Djava.io.tmpdir="\"$CATALINA_TMPDIR\"" \
      org.apache.catalina.startup.Bootstrap "$@" start \
      >> "$CATALINA_OUT" 2>&1 "&"

  else
    eval $_NOHUP "\"$_RUNJAVA\"" "\"$CATALINA_LOGGING_CONFIG\"" $LOGGING_MANAGER "$JAVA_OPTS" "$CATALINA_OPTS" \
      -D$ENDORSED_PROP="\"$JAVA_ENDORSED_DIRS\"" \
      -classpath "\"$CLASSPATH\"" \
      -Dcatalina.base="\"$CATALINA_BASE\"" \
      -Dcatalina.home="\"$CATALINA_HOME\"" \
      -Djava.io.tmpdir="\"$CATALINA_TMPDIR\"" \
      org.apache.catalina.startup.Bootstrap "$@" start \
      >> "$CATALINA_OUT" 2>&1 "&"

  fi

  if [ ! -z "$CATALINA_PID" ]; then
    echo $! > "$CATALINA_PID"
  fi

  echo "Tomcat started."

elif [ "$1" = "stop" ] ; then

  shift

  SLEEP=5
  if [ ! -z "$1" ]; then
    echo $1 | grep "[^0-9]" >/dev/null 2>&1
    if [ $? -gt 0 ]; then
      SLEEP=$1
      shift
    fi
  fi

  FORCE=0
  if [ "$1" = "-force" ]; then
    shift
    FORCE=1
  fi

  if [ ! -z "$CATALINA_PID" ]; then
    if [ -f "$CATALINA_PID" ]; then
      if [ -s "$CATALINA_PID" ]; then
        kill -0 `cat "$CATALINA_PID"` >/dev/null 2>&1
        if [ $? -gt 0 ]; then
          echo "PID file found but either no matching process was found or the current user does not have permission to stop the process. Stop aborted."
          exit 1
        fi
      else
        echo "PID file is empty and has been ignored."
      fi
    else
      echo "\$CATALINA_PID was set but the specified file does not exist. Is Tomcat running? Stop aborted."
      exit 1
    fi
  fi

  eval "\"$_RUNJAVA\"" $LOGGING_MANAGER "$JAVA_OPTS" \
    -D$ENDORSED_PROP="\"$JAVA_ENDORSED_DIRS\"" \
    -classpath "\"$CLASSPATH\"" \
    -Dcatalina.base="\"$CATALINA_BASE\"" \
    -Dcatalina.home="\"$CATALINA_HOME\"" \
    -Djava.io.tmpdir="\"$CATALINA_TMPDIR\"" \
    org.apache.catalina.startup.Bootstrap "$@" stop

  # stop failed. Shutdown port disabled? Try a normal kill.
  if [ $? != 0 ]; then
    if [ ! -z "$CATALINA_PID" ]; then
      echo "The stop command failed. Attempting to signal the process to stop through OS signal."
      kill -15 `cat "$CATALINA_PID"` >/dev/null 2>&1
    fi
  fi

  if [ ! -z "$CATALINA_PID" ]; then
    if [ -f "$CATALINA_PID" ]; then
      while [ $SLEEP -ge 0 ]; do
        kill -0 `cat "$CATALINA_PID"` >/dev/null 2>&1
        if [ $? -gt 0 ]; then
          rm -f "$CATALINA_PID" >/dev/null 2>&1
          if [ $? != 0 ]; then
            if [ -w "$CATALINA_PID" ]; then
              cat /dev/null > "$CATALINA_PID"
              # If Tomcat has stopped don't try and force a stop with an empty PID file
              FORCE=0
            else
              echo "The PID file could not be removed or cleared."
            fi
          fi
          echo "Tomcat stopped."
          break
        fi
        if [ $SLEEP -gt 0 ]; then
          sleep 1
        fi
        if [ $SLEEP -eq 0 ]; then
          echo "Tomcat did not stop in time."
          if [ $FORCE -eq 0 ]; then
            echo "PID file was not removed."
          fi
          echo "To aid diagnostics a thread dump has been written to standard out."
          kill -3 `cat "$CATALINA_PID"`
        fi
        SLEEP=`expr $SLEEP - 1 `
      done
    fi
  fi

  KILL_SLEEP_INTERVAL=5
  if [ $FORCE -eq 1 ]; then
    if [ -z "$CATALINA_PID" ]; then
      echo "Kill failed: \$CATALINA_PID not set"
    else
      if [ -f "$CATALINA_PID" ]; then
        PID=`cat "$CATALINA_PID"`
        echo "Killing Tomcat with the PID: $PID"
        kill -9 $PID
        while [ $KILL_SLEEP_INTERVAL -ge 0 ]; do
            kill -0 `cat "$CATALINA_PID"` >/dev/null 2>&1
            if [ $? -gt 0 ]; then
                rm -f "$CATALINA_PID" >/dev/null 2>&1
                if [ $? != 0 ]; then
                    if [ -w "$CATALINA_PID" ]; then
                        cat /dev/null > "$CATALINA_PID"
                    else
                        echo "The PID file could not be removed."
                    fi
                fi
                echo "The Tomcat process has been killed."
                break
            fi
            if [ $KILL_SLEEP_INTERVAL -gt 0 ]; then
                sleep 1
            fi
            KILL_SLEEP_INTERVAL=`expr $KILL_SLEEP_INTERVAL - 1 `
        done
        if [ $KILL_SLEEP_INTERVAL -lt 0 ]; then
            echo "Tomcat has not been killed completely yet. The process might be waiting on some system call or might be UNINTERRUPTIBLE."
        fi
      fi
    fi
  fi

elif [ "$1" = "configtest" ] ; then

    eval "\"$_RUNJAVA\"" $LOGGING_MANAGER "$JAVA_OPTS" \
      -D$ENDORSED_PROP="\"$JAVA_ENDORSED_DIRS\"" \
      -classpath "\"$CLASSPATH\"" \
      -Dcatalina.base="\"$CATALINA_BASE\"" \
      -Dcatalina.home="\"$CATALINA_HOME\"" \
      -Djava.io.tmpdir="\"$CATALINA_TMPDIR\"" \
      org.apache.catalina.startup.Bootstrap configtest
    result=$?
    if [ $result -ne 0 ]; then
        echo "Configuration error detected!"
    fi
    exit $result

elif [ "$1" = "version" ] ; then

    "$_RUNJAVA"   \
      -classpath "$CATALINA_HOME/lib/catalina.jar" \
      org.apache.catalina.util.ServerInfo

else

  echo "Usage: catalina.sh ( commands ... )"
  echo "commands:"
  if $os400; then
    echo "  debug             Start Catalina in a debugger (not available on OS400)"
    echo "  debug -security   Debug Catalina with a security manager (not available on OS400)"
  else
    echo "  debug             Start Catalina in a debugger"
    echo "  debug -security   Debug Catalina with a security manager"
  fi
  echo "  jpda start        Start Catalina under JPDA debugger"
  echo "  run               Start Catalina in the current window"
  echo "  run -security     Start in the current window with security manager"
  echo "  start             Start Catalina in a separate window"
  echo "  start -security   Start in a separate window with security manager"
  echo "  stop              Stop Catalina, waiting up to 5 seconds for the process to end"
  echo "  stop n            Stop Catalina, waiting up to n seconds for the process to end"
  echo "  stop -force       Stop Catalina, wait up to 5 seconds and then use kill -KILL if still running"
  echo "  stop n -force     Stop Catalina, wait up to n seconds and then use kill -KILL if still running"
  echo "  configtest        Run a basic syntax check on server.xml - check exit code for result"
  echo "  version           What version of tomcat are you running?"
  echo "Note: Waiting for the process to end and use of the -force option require that \$CATALINA_PID is defined"
  exit 1

fi

得出结论 org.apache.catalina.startup.Bootstrap 为 Tomcat的核心启动类

Tomcat 配置文件

`web.xml`


This document defines default values for *all* web applications loaded into this instance of Tomcat.  As each application is         deployed, this file is processed, followed by the   "/WEB-INF/web.xml" deployment descriptor from your own applications.   

所有的web应用，它们的默认值都取决于conf/web.xml， 你配置的web.xml的信息，是可以覆盖的，可以类比于类的继承和方法的复写。

`context.xml`

The contents of this file will be loaded for each web application 

每个web应用都加载conf/context.xml。
我们说Context代表了一个web应用，那么web应用的目录：WEB-INF（web的元数据目录）、META-INF（元数据目录）。这里的WatchedResource标签，翻译一下：监听资源，也即监听了WEB-INF/web.xml和/${catalina.base}/conf/web.xml，改动后，立马重新加载应用，如果我需要监听其他资源呢？

<Context>
    <WatchedResource>WEB-INF/web.xml</WatchedResource>
    <WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>
</Context>

Tomcat的work目录

jsp最终要转变为Servlet，而Servlet是一个java类，类是需要编译处理的，这时是不是需要一个目录，来保存jsp生成的servlet文件，而这个目录就称之为工作目录。

简介