我已经深究了这个问题，原来我错过了另一个android env变量.

I've got to the bottom of this issue, turns out I've missed another android env variable.

在上述情况下，我错过了 ANDROID_BUILD_TOOLS

In the above case I've missed ANDROID_BUILD_TOOLS

在撰写本文时，以下是鸦片所需的Env变量列表.

At the point of writing this, below are the list of Env variables required for appium.

ANDROID_HOME=/Users/n.nadarajah/Library/Android/sdk
JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_151.jdk/
Contents/Home/bin
ANDROID_PLATFORM_TOOLS=$ANDROID_HOME/platform-tools
ANDROID_TOOLS=$ANDROID_HOME/tools
ANDROID_BUILD_TOOLS=$ANDROID_HOME/build-tools/27.0.3

将上述所有env变量附加到$ PATH

Append all the above env variables to $PATH