新版的 play framework 执行 play deps 时，会自动删除 lib 目录中，未在依赖文件中定义的 jar 包：

$ play deps
~        _            _
~  _ __ | | __ _ _  _| |
~ | '_ \| |/ _' | || |_|
~ |  __/|_|\____|\__ (_)
~ |_|            |__/
~
~ play! 1.4.5, https://www.playframework.com
~
~ Resolving dependencies using F:\Myspace\anda\aderp-admin\conf\dependencies.yml
~
~
~ Installing resolved dependencies,
~
~       modules/secure -> D:\play\play-1.4.5\modules\secure
~       modules/crud -> D:\play\play-1.4.5\modules\crud
~
~ Synchronizing, deleting unknown dependencies
~
~       Deleted: F:\Myspace\anda\aderp-admin\lib\antlr-2.7.4.jar
~       Deleted: F:\Myspace\anda\aderp-admin\lib\bonecp-0.7.0.jar
~       Deleted: F:\Myspace\anda\aderp-admin\lib\chardet-1.0.jar
~       Deleted: F:\Myspace\anda\aderp-admin\lib\commons-beanutils-1.8.3.jar
~       Deleted: ...

要解决这个问题其实很简单，在 play deps 命令后面加一个 –nosync 参数就可以了：

play deps --nosync
~        _            _
~  _ __ | | __ _ _  _| |
~ | '_ \| |/ _' | || |_|
~ |  __/|_|\____|\__ (_)
~ |_|            |__/
~
~ play! 1.4.5, https://www.playframework.com
~
~ Resolving dependencies using F:\Myspace\anda\aderp-admin\conf\dependencies.yml
~
~
~ Installing resolved dependencies,
~
~       modules/secure -> D:\play\play-1.4.5\modules\secure
~       modules/crud -> D:\play\play-1.4.5\modules\crud
~
~ *****************************************************************************
~ WARNING: Your lib/ and modules/ directories are not synced with current dependencies (don't use --nosync to automatically delete them)
~
~       Unknown: F:\Myspace\anda\aderp-admin\lib\antlr-2.7.4.jar
~       Unknown: F:\Myspace\anda\aderp-admin\lib\axis.jar
~       Unknown: F:\Myspace\anda\aderp-admin\lib\bonecp-0.7.0.jar
~       Unknown: F:\Myspace\anda\aderp-admin\lib\chardet-1.0.jar
~       Unknown: F:\Myspace\anda\aderp-admin\lib\commons-beanutils-1.8.3.jar
~       Unknown: ...