Unknown error: Unable to build: the file dx.jar was not loaded from the SDK folder!

　　莫名其妙出现这个错误：

[2020-04-14 05:40:51 - Dex Loader] Failed to load D:\adt-bundle-windows-x86_64-20190307\sdk\build-tools\28.0.3\lib\dx.jar
[2020-04-14 05:40:51 - Android-CameraFps] Unknown error: Unable to build: the file dx.jar was not loaded from the SDK folder!      

　　解决办法：

• 检查build-tools下有几个目录。比如吾有25.0.2和其他。
• 打开project.properties，然后加上一行：sdk.buildtools=25.0.2