一个Tomcat的问题。很多人兴冲冲的下载了一个Tomcat，跑到bin看到一个startup.bat就去执行，结果提示Neither the JAVA_HOME nor the JRE_HOME environment variable is defined At least one of these environment variable is needed to run this program。好，再去下载个最新版本的JDK,Install完成之后却还是提示Neither the JAVA_HOME nor the JRE_HOME environment variable is defined At least one of these environment variable is needed to run this program。搞得对Tomcat的学习热情冷了一半。

原因是后来较新版本的JDK（例如我使用的JDK1.6）安装完不会自动登记环境变量JAVA_HOME，JRE_HOME。像我在单位的环境，我的用户是受限制的(PowerUser)，不方便设环境变量，于是我就找到了另外一个方法。

先看Tomcat的startup.bat，它调用了catalina.bat,而catalina.bat则调用了setclasspath.bat。只要在setclasspath.bat的开头声明环境变量，如我的就是：

rem ---------------------------------------------------------------------------
rem Set CLASSPATH and Java options
rem
rem $Id: setclasspath.bat 505241 2007-02-09 10:22:58Z jfclere $
rem ---------------------------------------------------------------------------

set JAVA_HOME=D:\Java\jdk1.6.0_11
set JRE_HOME=D:\Java\jre6

rem Make sure prerequisite environment variables are set
if not "%JAVA_HOME%" == "" goto gotJdkHome
if not "%JRE_HOME%" == "" goto gotJreHome
echo Neither the JAVA_HOME nor the JRE_HOME environment variable is defined
echo At least one of these environment variable is needed to run this program
goto exit
......

这样在每次运行startup.bat时就注册了JAVA_HOME，JRE_HOME。控制台窗口关闭后，这两个变量也将消失，不会再占用内存

在linux中安装tomcat 同样的问题解决方法

在linux下安装好tomcat启动时报如下错误：

Neither the JAVA_HOME nor the JRE_HOME environment variable is defined 
At least one of these environment variable is needed to run this program

原因：找不到jdk或者jre路径。

解决办法：在setclasspath.bat的开头声明环境变量，打开tomcat的bin目录下面的setclasspath.sh，添加红色部分，路径修改为自己机器jdk和jre路径即可。

#!/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.

# -----------------------------------------------------------------------------
#  Set CLASSPATH and Java options
#
#  $Id: setclasspath.sh 795037 2009-07-17 10:52:16Z markt $
# -----------------------------------------------------------------------------

export JAVA_HOME=/usr/local/jdk1.6.0_31
export JRE_HOME=/usr/local/jdk1.6.0_31/jre 

# Make sure prerequisite environment variables are set
if [ -z "$JAVA_HOME" -a -z "$JRE_HOME" ]; then
  # Bugzilla 37284 (reviewed).
  if $darwin; then
    if [ -d "/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home" ]; then
      export JAVA_HOME="/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home"
    fi
  else
    JAVA_PATH=`which java 2>/dev/null`
    if [ "x$JAVA_PATH" != "x" ]; then
      JAVA_PATH=`dirname $JAVA_PATH 2>/dev/null`
      JRE_HOME=`dirname $JAVA_PATH 2>/dev/null`
    fi
    if [ "x$JRE_HOME" = "x" ]; then
      # XXX: Should we try other locations?
      if [ -x /usr/bin/java ]; then
        JRE_HOME=/usr
      fi
    fi
  fi
  if [ -z "$JAVA_HOME" -a -z "$JRE_HOME" ]; then
    echo "Neither the JAVA_HOME nor the JRE_HOME environment variable is defined"
    echo "At least one of these environment variable is needed to run this program"
    exit 1
  fi
fi
if [ -z "$JAVA_HOME" -a "$1" = "debug" ]; then
  echo "JAVA_HOME should point to a JDK in order to run in debug mode."
  exit 1
fi
if [ -z "$JRE_HOME" ]; then
  JRE_HOME="$JAVA_HOME"
fi

# If we're running under jdb, we need a full jdk.
if [ "$1" = "debug" ] ; then
  if [ "$os400" = "true" ]; then
    if [ ! -x "$JAVA_HOME"/bin/java -o ! -x "$JAVA_HOME"/bin/javac ]; then
      echo "The JAVA_HOME environment variable is not defined correctly"
      echo "This environment variable is needed to run this program"
      echo "NB: JAVA_HOME should point to a JDK not a JRE"
      exit 1
    fi
  else
    if [ ! -x "$JAVA_HOME"/bin/java -o ! -x "$JAVA_HOME"/bin/jdb -o ! -x "$JAVA_HOME"/bin/javac ]; then
      echo "The JAVA_HOME environment variable is not defined correctly"
      echo "This environment variable is needed to run this program"
      echo "NB: JAVA_HOME should point to a JDK not a JRE"
      exit 1
    fi
  fi
fi
if [ -z "$BASEDIR" ]; then
  echo "The BASEDIR environment variable is not defined"
  echo "This environment variable is needed to run this program"
  exit 1
fi
if [ ! -x "$BASEDIR"/bin/setclasspath.sh ]; then
  if $os400; then
    # -x 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
    eval
  else
    echo "The BASEDIR environment variable is not defined correctly"
    echo "This environment variable is needed to run this program"
    exit 1
  fi
fi

# Don't override the endorsed dir if the user has set it previously
if [ -z "$JAVA_ENDORSED_DIRS" ]; then
  # Set the default -Djava.endorsed.dirs argument
  JAVA_ENDORSED_DIRS="$BASEDIR"/endorsed
fi

# OSX hack to CLASSPATH
JIKESPATH=
if [ `uname -s` = "Darwin" ]; then
  OSXHACK="/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Classes"
  if [ -d "$OSXHACK" ]; then
    for i in "$OSXHACK"/*.jar; do
      JIKESPATH="$JIKESPATH":"$i"
    done
  fi
fi

# Set standard commands for invoking Java.
_RUNJAVA="$JRE_HOME"/bin/java
if [ "$os400" != "true" ]; then
  _RUNJDB="$JAVA_HOME"/bin/jdb
fi