保存成bat（utf-8 无签名 编码）
右键以管理员权限运行
修改JAVAINSTALLPATH 为JAVA SDK 安装目录（默认用C:\PROGRAM FILES\JAVA\）即可；
只在 用户变量下 创建，会事先保存好用户原有的“JAVA_HOME,JRE_HOME,PATH,CLASSPATH”等变量到"OlD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT"（按JAVA_HOME,JRE_HOME,PATH,CLASSPATH顺序保存），然后删除用户JAVA_HOME,JRE_HOME,PATH,CLASSPATH”变量，并创建JAVA SDK变量。之后会打开环境变量设置窗口和"OlD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT"，按需补充原有变量值。
CD /D "%~dp0" ::PAUSE SET JAVAINSTALLPATH=C:\PROGRAM FILES\JAVA START SYSTEMPROPERTIESCOMPUTERNAME.EXE DEL "OlD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT" WMIC ENVIRONMENT WHERE "NAME=‘JAVA_HOME‘ AND USERNAME LIKE ‘%%%USERNAME%‘" GET VARIABLEVALUE >> "OlD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT" WMIC ENVIRONMENT WHERE "NAME=‘JRE_HOME‘ AND USERNAME LIKE ‘%%%USERNAME%‘" GET VARIABLEVALUE >> "OlD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT" WMIC ENVIRONMENT WHERE "NAME=‘PATH‘ AND USERNAME LIKE ‘%%%USERNAME%‘" GET VARIABLEVALUE >> "OlD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT" WMIC ENVIRONMENT WHERE "NAME=‘CLASSPATH‘ AND USERNAME LIKE ‘%%%USERNAME%‘" GET VARIABLEVALUE >> "OlD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT" ::PAUSE WMIC ENVIRONMENT WHERE "NAME=‘JAVA_HOME‘ AND USERNAME LIKE ‘%%%USERNAME%‘" DELETE WMIC ENVIRONMENT WHERE "NAME=‘JRE_HOME‘ AND USERNAME LIKE ‘%%%USERNAME%‘" DELETE WMIC ENVIRONMENT WHERE "NAME=‘PATH‘ AND USERNAME LIKE ‘%%%USERNAME%‘" DELETE WMIC ENVIRONMENT WHERE "NAME=‘CLASSPATH‘ AND USERNAME LIKE ‘%%%USERNAME%‘" DELETE ::PAUSE WMIC ENVIRONMENT CREATE NAME="JAVA_HOME",USERNAME="%USERNAME%",VARIABLEVALUE="‘%JAVAINSTALLPATH%JDK-9‘" WMIC ENVIRONMENT CREATE NAME="JRE_HOME", USERNAME="%USERNAME%",VARIABLEVALUE="‘%JAVAINSTALLPATH%JRE-9‘" WMIC ENVIRONMENT CREATE NAME="PATH", USERNAME="%USERNAME%",VARIABLEVALUE=".;%%JAVA_HOME%%\BIN;%%JRE_HOME%%\BIN" WMIC ENVIRONMENT CREATE NAME="CLASSPATH",USERNAME="%USERNAME%",VARIABLEVALUE=".;%%JAVA_HOME%%\LIB;%%JRE_HOME%%\LIB" START "OLD-JAVA_HOME,JRE_HOME,PATH,CLASSPATH.TXT" PAUSE
原文：http://www.cnblogs.com/Chary/p/7742098.html