Go 是一种静态编译型语言，写完源代码后，需要编译成二进制可执行文件，才能运行程序看到相应的效果。我们在开发 Go 程序的过程中经常需要调试，如果没有热加载功能，这将是非常痛苦的一件事。
Air 是 Go 生态中一个可以实现热加载的库，在开发 Go 项目的时候引入 Air，可以很大程度上提升开发调试的效率。
安装Air
go get -u github.com/cosmtrek/air
安装完成后，我们执行air -h可以看到Air的基本用法：
$ air -h
Usage of air:
-c string
config path
-d debug mode
-v show version
热加载配置
在要开发的 Go 项目目录下新建一个 .air.conf，写入基本的配置信息。
# Config file for [Air](https://github.com/cosmtrek/air) in TOML format
# Working directory
# . or absolute path, please note that the directories following must be under root.
root = "."
tmp_dir = "tmp"
[build]
# Just plain old shell command. You could use `make` as well.
cmd = "make build"
# Binary file yields from `cmd`.
bin = "webapi server"
# Customize binary.
full_bin = "APP_ENV=dev APP_USER=air ./webapi server"
# Watch these filename extensions.
include_ext = ["go", "yaml"]
# Ignore these filename extensions or directories.
exclude_dir = ["config", "tmp", "vendor", "tests"]
# Watch these directories if you specified.
include_dir = []
# Exclude files.
exclude_file = []
# This log file places in your tmp_dir.
log = "air.log"
# It's not necessary to trigger build each time file changes if it's too frequent.
delay = 1000 # ms
# Stop running old binary when build errors occur.
stop_on_error = true
# Send Interrupt signal before killing process (windows does not support this feature)
send_interrupt = false
# Delay after sending Interrupt signal
kill_delay = 500 # ms
[log]
# Show log time
time = false
[color]
# Customize each part's color. If no color found, use the raw app log.
main = "magenta"
watcher = "cyan"
build = "yellow"
runner = "green"
[misc]
# Delete tmp directory on exit
clean_on_exit = true
例如我们开发的项目名称叫做 webapi ，在引入热加载配置之前，我们要调试程序，需要进行的操作为：
## 编译生成可执行文件
go build -o webapi main.go
## 启动http服务
./webapi server
那么我们可以在热加载文件中配置成：
[build]
cmd = "go build -o webapi main.go"
bin = "webapi server"
full_bin = "APP_ENV=dev APP_USER=air ./webapi server"
include_ext = ["go", "yaml"]
热加载方式运行
air -c .air.conf
我们在项目根目录下运行上面的命令，项目就启动了，Air 会监听项目中的 .go、.yaml 类型文件，一旦文件有修改，Air 会自动编译程序，并重新启动。
有了热加载，我们就可以专注于写业务逻辑了，预览调试起来方便的很。