运行

 $cordova build android

 [Error: ANDROID_HOME is not set and "android" command not in your PATH. You must fulfill at least one of these conditions.]
ERROR building one of the platforms: Error: /Users/albert/Bloom/BloomateStore/platforms/android/cordova/build: Command failed with exit code 2
You may not have the required environment or OS to build this project
Error: /Users/albert/Bloom/BloomateStore/platforms/android/cordova/build: Command failed with exit code 2
    at ChildProcess.whenDone (/usr/local/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/superspawn.js:135:23)
    at ChildProcess.EventEmitter.emit (events.js:98:17)
    at maybeClose (child_process.js:735:16)
    at Process.ChildProcess._handle.onexit (child_process.js:802:5)

请问这个ANDROID_HOME应该如何设置，在网上找了一圈，都没有解决这个问题
PS:
OSX系统 build ios 成功了
android 之前 build 成功过 现在则一直报这个错，不知道是动了哪里了