TomCat启动找不到配置的环境变量解决_缓存

错误描述

通过tomcat/bin/startup.bat启动tomcat时遇到报错

the jre_home environment variable is not defined correctly
this environment variable is needed to run this program

终端界面一闪而过,发现启动失败,这是由于tomcat在环境变量中检索java环境是出现错误

追根溯源

打开bat文件查看,其中没有关于jre_home的报错信息,发现又运行了catalina.bat

set "executable=%catalina_home%\bin\catalina.bat"

既没有关于catalina环境配置的报错,又执行了catalina.bat,那么我们就查看一下是不是在catalina.bat中抛出的jre环境变量报错

阅读bat代码,发现第一个有关java环境的代码块

rem get standard java environment variables
if exist "%catalina_home%\bin\setclasspath.bat" goto oksetclasspath
echo cannot find "%catalina_home%\bin\setclasspath.bat"
echo this file is needed to run this program
goto end
:oksetclasspath
call "%catalina_home%\bin\setclasspath.bat" %1
if errorlevel 1 goto end

这里尝试从setclasspath.bat中获取java environment,正符合我们的猜想,继续查看setclasspath.bat

阅读bat,发现我们触发的报错代码

: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

回溯调用源

: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

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

通过代码我们知道,如果我们不在"debug"模式下,就会继续检索jre或jdk任意一个来支持我们在非调试模式下的运行,很明显,我们在查找jre_home时就出现了问题,从而引发报错,接下来尝试解决这个问题

问题解决

1.添加jre_home环境变量

win+r 输入sysdm.cpl打开系统属性->高级->环境变量
在系统变量中新建jre_home 值为jre路径

到这里,如果问题解决了,恭喜你,但是很多人和我一样配置完毕后运行还是报错,请参考方法2

2.直接在脚本中增加静态变量

既然最终会在setclasspath.bat中查找环境变量,那么我们就直接在这里指明环境变量位置,而不必让其从系统配置中逐步检索了

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 ---------------------------------------------------------------------------

rem make sure prerequisite environment variables are set
set java_home=d:\java_8
set jre_home=d:\java_8\jre

直接在脚本开头写好home参数,注意将路径改为自己的

再次运行,成功