編寫switchjava.bat，保存到System32目錄下。
http://blog.163.com/lai_xiao_hui/blog/static/123037324201511344249176/
@echo off
rem 切換Java jdk版本
echo 請以管理員來進行切換
java -version
:menu
echo =============================================
echo 請選擇要切換的jdk版本
echo 1：Java jdk 1.7
echo 2：Java jdk 1.8
echo 3: 取消
echo =============================================
set /p ch=請選擇：
if "%ch%"=="1" goto java1.7
if "%ch%"=="2" goto java1.8
if "%ch%"=="3" goto exit
goto menu
:java1.7
set JAVA_HOME=C:\Program Files\Java\jdk1.7.0_15
set JRE_HOME=C:\Program Files\Java\jre7
set JAVA_VERSION=1.7
goto exec
:java1.8
set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_20
set JRE_HOME=C:\Program Files\Java\jre1.8.0_20
set JAVA_VERSION=1.8
goto exec
:exec
reg add "HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Development Kit" /v CurrentVersion /t REG_SZ /f /d "%JAVA_VERSION%"
reg add "HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment" /v CurrentVersion /t REG_SZ /f /d "%JAVA_VERSION%"
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v JAVA_HOME /t REG_SZ /f /d "%JAVA_HOME%"
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v JRE_HOME /t REG_SZ /f /d "%JRE_HOME%"
del /f "C:\Windows\System32\java.exe"
copy /Y "%JAVA_HOME%\bin\java.exe" "C:\Windows\System32\java.exe"
del /f "C:\Windows\System32\javaw.exe"
copy /Y "%JAVA_HOME%\bin\javaw.exe" "C:\Windows\System32\javaw.exe"
del /f "C:\Windows\System32\javaws.exe"
copy /Y "%JAVA_HOME%\bin\javaws.exe" "C:\Windows\System32\javaws.exe"
set JAVA_PATH=C:\ProgramData\Oracle\Java\javapath
del /f "%JAVA_PATH%\java.exe"
mklink "%JAVA_PATH%\java.exe" "%JAVA_HOME%\bin\java.exe"
del /f "%JAVA_PATH%\javaw.exe"
mklink "%JAVA_PATH%\javaw.exe" "%JAVA_HOME%\bin\javaw.exe"
del /f "%JAVA_PATH%\javaws.exe"
mklink "%JAVA_PATH%\javaws.exe" "%JAVA_HOME%\bin\javaws.exe"
echo 已切換到JDK %JAVA_VERSION%
goto exit
:exit