在 Mac 设备的终端执行命令 ./gradlew :xxx:clean :xxx:assembleRelease 编译 xxx.aar 时，报错：
> Task :xxx:compileReleaseJavaWithJavac FAILED
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':xxx:compileReleaseJavaWithJavac'.
> Could not find tools.jar. Please check that /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home contains a valid JDK installation.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
解决方案：
第一步：查看 java 版本，执行命令：java -version
第二步：查看 javac 版本，执行命令：javac -version
第三步：如果 java 和 javac 版本不一致，或者需要升级 java, javac 版本，在终端执行命令 /usr/libexec/java_home -V | grep jdk，获取 java 虚拟机列表
/usr/libexec/java_home -V | grep jdk
Matching Java Virtual Machines (2):
1.8.321.07 (x86_64) "Oracle Corporation" - "Java" /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home
1.8.0_321 (x86_64) "Oracle Corporation" - "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_321.jdk/Contents/Home
第四步：移除所有 java 虚拟机
rm -rf /Library/Internet Plug-Ins/JavaAppletPlugin.plugin
rm -rf /Library/Java/JavaVirtualMachines
第五步：下载 JDK（Java SE Developent Kit) 并安装，下载地址：https://www.oracle.com/java/technologies/downloads/#java8-mac
第六步：在 ~/.zshrc 或者 ~/.bash_profile 文件里配置环境变量 JAVA_HOME，此处以 ~/.zshrc 为例，在终端执行命令 vi ~/.zshrc，配置环境变量
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_321.jdk/Contents/Home
export PATH=$JAVA_HOME/bin:$PATH
温馨提示：
- 不要使用路径 Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home，使用该路径会报错 “Could not find tools.jar. Please check that /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home contains a valid JDK installation.”
- 不配置环境变量 JAVA_HOME，也会报错 “Could not find tools.jar. Please check that /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home contains a valid JDK installation.”
第七步：执行命令 source ~/.zshrc后，重启下终端
第八步：再次执行编译 xxx.aar 的命令：./gradlew :xxx:clean :xxx:assembleRelease ，成功打包出 .aar
