java在centos中，以daemon方式启动

以下内容基于Centos 6.3版本。

java开发的时候，需要注意以下几点：

1. 在main中，建立额外线程以保证一直运行；
2. 注册runtime的shutdownhook，以执行服务线程的退出前清理工作；

其他内容，都用shell脚本来控制，主要有：

$APP_HOME/bin/daemon.sh，该shell，支持link到服务目录，负责协调服务。

#!/bin/sh
#
# chkconfig:   - 20 80
# description: Starts and stops the redis daemon.
#
# Source function library.
### BEGIN INIT INFO
# Required-Start:    $local_fs $remote_fs $network $time $named
# Required-Stop:     $local_fs $remote_fs $network $time $named
# Default-Start:     3 5
# Default-Stop:      0 1 2 6
### END INIT INFO

NAME="sangame-daemon"
APP_USER="root"

. /etc/rc.d/init.d/functions
ulimit -HSn 65534

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"`

APP_HOME=`cd "$PRGDIR/.." >/dev/null; pwd`

APP_EXEC="$APP_HOME/bin/startup.sh"
#NAME="sangame-daemon-1"
#$APP_HOME="/data/home/sangame/sangame-server/daemon-1"
#APP_USER="sangame"
#shfile="$apphome/bin/startup.sh"
#exec="sh $shfile"
APP_PIDFILE="$APP_HOME/bin/app.pid"

#[ -e /etc/sysconfig/redis ] && . /etc/sysconfig/redis

start() {
    echo "Starting $NAME: $APP_HOME"
    daemon --user $APP_USER --pidfile $APP_PIDFILE $APP_EXEC
    retval=$?
    [ $retval -eq 0 ]
    return $retval
}

stop() {
    echo $"Stopping $NAME: $APP_HOME"
    killproc -p $APP_PIDFILE $NAME
    retval=$?
    echo
    [ $retval -eq 0 ]
    return $retval
}

restart() {
    stop
    start
}

rh_status() {
    echo $"Status $NAME: $APP_HOME"
    status -p $APP_PIDFILE $NAME
}

rh_status_q() {
    rh_status >/dev/null 2>&1
}

case "$1" in
    start)
        rh_status_q && exit 0
        $1
        sleep 5s
        rh_status
        ;;
    stop)
        rh_status_q || exit 0
        $1
        ;;
    restart)
        $1
        ;;
    status)
        rh_status
        ;;
    *)
        echo $"Usage: $0 {start|stop|status|restart}"
        exit 2
esac
exit $?

$APP_HOME/bin/startup.java，该shell，主要负责启动java主程序，同时设置pid文件。

#!/bin/sh
#
ulimit -HSn 65534

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"`

APP_HOME=`cd "$PRGDIR/.." >/dev/null; pwd`

cd $APP_HOME

JVM_START="-server -Xms256m -Xmx512m -Xss256k -XX:MaxPermSize=256m -XX:+UseParallelGC -XX:ParallelGCThreads=2 -XX:+UseParallelOldGC  -XX:MaxGCPauseMillis=100 -XX:+UseAdaptiveSizePolicy -verbose:gc -Xloggc:log/gc.log -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+PrintTenuringDistribution"

CLASSPATH="`for i in $APP_HOME/lib/*.jar ; do echo -n $i: ; done`."

LOGBACK_CONFIG_FILE="config/logback.xml"

echo "Using APP_HOME:                  $APP_HOME"               > ${APP_HOME}/log/app.out
echo "Using CLASSPATH:                 $CLASSPATH"              >> ${APP_HOME}/log/app.out
echo "Using JVM_START:                 $JVM_START"              >> ${APP_HOME}/log/app.out
echo "Using LOGBACK_CONFIG_FILE:       $LOGBACK_CONFIG_FILE"    >> ${APP_HOME}/log/app.out

java -classpath $CLASSPATH $JVM_START com.baolemon.sangame.server.rts.AppMain >> ${APP_HOME}/log/app.out 2>&1 &

echo -n $! > ${APP_HOME}/bin/app.pid

脚本注册为服务的代码：

cd /etc/init.d/
ln -s $APP_HOME/bin/daemon.sh xxx-daemon-n  #连接shell脚本
chkconfig --add xxx-daemon-n
chkconfig xxx-daemon-n on   #设置为自动启动

#测试效果
service xxx-daemon-n start
service xxx-daemon-n status
service xxx-daemon-n stop
service xxx-daemon-n restart