在XP上明明已经安装了JDK1.5并设置好了JAVA_HOME，可偏偏Tomcat在启动过程中找不到。
 
报错信息如下：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;提示找不到java_home各jre_home路径，何解？
原因不知道了，下面来看解决办法：
 
1、分析startup.bat启动脚本：发现其调用了catalina.bat,而catalina.bat调用了setclasspath.bat
2、在setclasspath.bat的头部定义了JAVA_HOME和JRE_HOME的值，那么在这里手动设置JAVA_HOME变量

复制代码代码如下:
rem ---------------------------------------------------------------------------
rem Set CLASSPATH and Java options
rem
rem $Id: setclasspath.bat 505241 2007-02-09 10:22:58Z jfclere $
rem ---------------------------------------------------------------------------
set JAVA_HOME=C:\Program Files\Java\jdk1.5.0_05
set JRE_HOME=C:\Program Files\Java\jre1.5.0_05
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
:gotJreHome
if not exist "%JRE_HOME%\bin\java.exe" goto noJavaHome
if not exist "%JRE_HOME%\bin\javaw.exe" goto noJavaHome
if not ""%1"" == ""debug"" goto okJavaHome
echo JAVA_HOME should point to a JDK in order to run in debug mode.
goto exit
:gotJdkHome
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
if not "%JRE_HOME%" == "" goto okJavaHome
set JRE_HOME=%JAVA_HOME%
goto okJavaHome
:noJavaHome
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
goto exit
:okJavaHome
if not "" == "" goto gotBasedir
echo The BASEDIR environment variable is not defined
echo This environment variable is needed to run this program
goto exit
:gotBasedir
if exist "" goto okBasedir
echo The BASEDIR environment variable is not defined correctly
echo This environment variable is needed to run this program
goto exit
:okBasedir
rem Set the default -Djava.endorsed.dirs argument
set JAVA_ENDORSED_DIRS="%JAVA_HOME%\bin\tools.jar" goto noJavac
set CLASSPATH=%JAVA_HOME%\lib\tools.jar
:noJavac
rem Set standard command for invoking Java.
rem Note that NT requires a window name argument when using start.
rem Also note the quoting as JAVA_HOME may contain spaces.
set _RUNJAVA="%JRE_HOME%\bin\java"
set _RUNJAVAW="%JRE_HOME%\bin\javaw"
set _RUNJDB="%JAVA_HOME%\bin\jdb"
set _RUNJAVAC="%JAVA_HOME%\bin\javac"
goto end
:exit
exit /b 1
:end

3、重启tomcat，敲入http://localhost:8080验证，问题解决。
 
tomcat5需要jdk1.6做支撑，jdk1.5不能够。