简短答案:

仅出于副作用导入软件包.

Short answer:

It's for importing a package solely for its side-effects.

来自 Go规范:

要仅出于副作用(初始化)导入软件包，请使用空白标识符作为显式软件包名称:

To import a package solely for its side-effects (initialization), use the blank identifier as explicit package name:

导入_"lib/math"

import _ "lib/math"

在sqlite3中

对于 go-sqlite3 ，下划线import用于将sqlite3驱动程序注册为init()函数中的数据库驱动程序的副作用，而无需导入任何其他功能:

In sqlite3

In the case of go-sqlite3, the underscore import is used for the side-effect of registering the sqlite3 driver as a database driver in the init() function, without importing any other functions:

sql.Register("sqlite3", &SQLiteDriver{})

以这种方式注册后，sqlite3可以与代码中标准库的sql接口一起使用，如示例所示:

Once it's registered in this way, sqlite3 can be used with the standard library's sql interface in your code like in the example:

db, err := sql.Open("sqlite3", "./foo.db")