Get java version from batch file

问题:

How to get java version and want to get '6' out of java version from batch file. I tried below script, but it didn't work.

    REM check java exists using JAVA_HOME system variable

if "%JAVA_HOME%" == "" (
ECHO Installing java
start /w jdk.exe /s
SETX -m JAVA_HOME "C:\Program Files\Java\jdk1.6.0_31"
ECHO java installed successfully
) ELSE (
ECHO checking java version
goto check_java_version
)

REM check java version using JAVA_HOME system variable
:check_java_version
set PATH=%PATH%;%JAVA_HOME%\bin
for /f tokens^=2-5^ delims^=.-_^" %%j in ('%JAVA_HOME%/bin/java -version 2^>^&1') do set "jver=%%j%%k%%l%%m"
echo %jver%

JAVA_HOME has "C:\Program Files\Java\jdk1.6.0_31" value.

回答1:

for /f tokens^=2-5^ delims^=.-_^" %j in ('java -fullversion 2^>^&1') do @set "jver=%j%k%l%m"

This will store the java version into jver variable and as integer And you can use it for comparisons .E.G

if %jver% LSS 16000 echo not supported version

.You can use more major version by removing %k and %l and %m.This command prompt version.

For .bat use this:

@echo off
PATH %PATH%;%JAVA_HOME%\bin\
for /f tokens^=2-5^ delims^=.-_^" %%j in ('java -fullversion 2^>^&1') do set "jver=%%j%%k%%l%%m"

According to my tests this is the fastest way to get the java version from bat (as it uses only internal commands and not external ones as FIND,FINDSTR and does not use GOTO which also can slow the script). Some JDK vendors does not support -fullversion switch or their implementation is not the same as this one provided by Oracle (better avoid them).

回答2:

You can do this with awk:

>java -fullversion 2>&1|awk "{print $NF}"
"1.7.0_21-b11"

>java -fullversion 2>&1|awk -F\" "{print $(NF-1)}"
1.7.0_21-b11

---

Script example:

@ECHO OFF &SETLOCAL
FOR /f %%a IN ('java -fullversion 2^>^&1^|awk "{print $NF}"') DO SET "javaversion=%%a"
IF DEFINED javaversion (ECHO java version: %javaversion%) ELSE ECHO java NOT found

output is: java version: "1.7.0_21-b11"
awk for Windows

回答3:

it should be java -version // if environment path is already set

or %JAVA_HOME%/bin/java -version //if path is not already set

回答4:

Within a block statement, %var% would be echoed as the value of var BEFORE the block was entered.

Move the echo outside of the block or echo %%g or call echo %%javaver%% or invoke SETLOCAL enabledelayedexpansion and echo !javaver!

回答5:

it will be surly idiot but why do not just print JAVA_HOME path ?