參考https://blog.csdn.net/qq_30507287/article/details/53981851
今天在服務器的tomcat上部署.war文件，雙擊startup閃退，然后在tomcat/bin目錄下，shift+右鍵，打開命令行窗口，然后把startup.bat拖進命令行窗口，回車，出現“jre_home environment variable is not defined correctly this environment variable is need”問題
在操作系統上明明已經安裝了JDK1.8並設置好了JAVA_HOME和JRE_HOME，可偏偏Tomcat在啟動過程中找不到並且在啟動startup.bat時閃退。
原因知道了，下面來看解決辦法：
1、分析startup.bat啟動腳本：發現其調用了catalina.bat,而catalina.bat調用了setclasspath.bat
2、在setclasspath.bat的頭部定義了JAVA_HOME和JRE_HOME的值，那么這里需要我們手動設置JAVA_HOME變量和JRE_HOME變量（紅色代碼為新添加）
注意：你所設置的變量要和自己的電腦中”環境變量“里的JAVA_HOME和JRE_HOME保持一致，我的是紅色的代碼。
@echo off
rem Licensed to the Apache Software Foundation (ASF) under one or more
rem contributor license agreements. See the NOTICE file distributed with
rem this work for additional information regarding copyright ownership.
rem The ASF licenses this file to You under the Apache License, Version 2.0
rem (the "License"); you may not use this file except in compliance with
rem the License. You may obtain a copy of the License at
rem
rem http://www.apache.org/licenses/LICENSE-2.0
rem
rem Unless required by applicable law or agreed to in writing, software
rem distributed under the License is distributed on an "AS IS" BASIS,
rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
rem See the License for the specific language governing permissions and
rem limitations under the License.
rem ---------------------------------------------------------------------------
rem Set JAVA_HOME or JRE_HOME if not already set, ensure any provided settings
rem are valid and consistent with the selected start-up options and set up the
rem endorsed directory.
rem ---------------------------------------------------------------------------
set JAVA_HOME=D:\Jdk8\jdk1.8.0_101
set JRE_HOME=D:\Jdk8\jdk1.8.0_101\jre
rem Make sure prerequisite environment variables are set
rem In debug mode we need a real JDK (JAVA_HOME)
if ""%1"" == ""debug"" goto needJavaHome
rem Otherwise either JRE or JDK are fine
if not "%JRE_HOME%" == "" goto gotJreHome
if not "%JAVA_HOME%" == "" goto gotJavaHome
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
:needJavaHome
rem Check if we have a usable JDK
if "%JAVA_HOME%" == "" goto noJavaHome
if not exist "%JAVA_HOME%\bin\java.exe" goto noJavaHome
if not exist "%JAVA_HOME%\bin\javaw.exe" goto noJavaHome
if not exist "%JAVA_HOME%\bin\jdb.exe" goto noJavaHome
if not exist "%JAVA_HOME%\bin\javac.exe" goto noJavaHome
set "JRE_HOME=%JAVA_HOME%"
goto okJava
:noJavaHome
echo The JAVA_HOME environment variable is not defined correctly.
echo It is needed to run this program in debug mode.
echo NB: JAVA_HOME should point to a JDK not a JRE.
goto exit
:gotJavaHome
rem No JRE given, use JAVA_HOME as JRE_HOME
set "JRE_HOME=%JAVA_HOME%"
:gotJreHome
rem Check if we have a usable JRE
if not exist "%JRE_HOME%\bin\java.exe" goto noJreHome
if not exist "%JRE_HOME%\bin\javaw.exe" goto noJreHome
goto okJava
:noJreHome
rem Needed at least a JRE
echo The JRE_HOME environment variable is not defined correctly
echo This environment variable is needed to run this program
goto exit
:okJava
rem Don't override the endorsed dir if the user has set it previously
if not "%JAVA_ENDORSED_DIRS%" == "" goto gotEndorseddir
rem Set the default -Djava.endorsed.dirs argument
set "JAVA_ENDORSED_DIRS=%CATALINA_HOME%\endorsed"
:gotEndorseddir
rem Don't override _RUNJAVA if the user has set it previously
if not "%_RUNJAVA%" == "" goto gotRunJava
rem Set standard command for invoking Java.
rem Also note the quoting as JRE_HOME may contain spaces.
set _RUNJAVA="%JRE_HOME%\bin\java.exe"
:gotRunJava
rem Don't override _RUNJDB if the user has set it previously
rem Also note the quoting as JAVA_HOME may contain spaces.
if not "%_RUNJDB%" == "" goto gotRunJdb
set _RUNJDB="%JAVA_HOME%\bin\jdb.exe"
:gotRunJdb
goto end
:exit
exit /b 1
:end
exit /b 0
3、添加變量后保存，並關閉文件，重新啟動tomcat，然后在瀏覽器中敲入http://localhost:8080驗證。顯示如下圖所示的界面則為修改成功，tomcat登錄也就成功了。