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启动流程分析

启动服务

服务源码

package main

import (
    "github.com/gin-gonic/gin"
)

func main() {
    // 创建一个默认的路由引擎
    engine := gin.Default()
    // 注册路由并设置一个匿名的 handlers，返回 JSON 格式数据
    engine.GET("/", func(ctx *gin.Context) {
        ctx.JSON(200, gin.H{
            "msg": "请求成功",
        })
    })
    // 启动服务，并监听端口 9090
    // 不填默认监听 0.0.0.0:8080
    _ = engine.Run(":9090")
}

启动输出

> go run main.go 
Alias tip: gor main.go
[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.

[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] GET    /                         --> main.main.func1 (3 handlers)
[GIN-debug] [WARNING] You trusted all proxies, this is NOT safe. We recommend you to set a value.
Please check https://pkg.go.dev/github.com/gin-gonic/gin#readme-don-t-trust-all-proxies for details.
[GIN-debug] Listening and serving HTTP on :9090
[GIN] 2023/02/25 - 13:53:44 | 200 |      24.987µs |       127.0.0.1 | GET      "/"

代码分析

import

在引入Gin框架时，包内相关的init()方法都会被执行

下面两个init方法：

  • github.com/gin-gonic/gin/context_appengine.go
  • github.com/gin-gonic/gin/mode.go

（1）github.com/gin-gonic/gin/context_appengine.go

源码：https://github.com/gin-gonic/gin/blob/v1.9.0/context_appengine.go#L10-L12

func init() {
    defaultPlatform = PlatformGoogleAppEngine
}

设置 defaultPlatform 为 PlatformGoogleAppEngine

源码：https://github.com/gin-gonic/gin/blob/v1.9.0/gin.go#L72-L80

// Trusted platforms
const (
    // PlatformGoogleAppEngine when running on Google App Engine. Trust X-Appengine-Remote-Addr
    // for determining the client's IP
    PlatformGoogleAppEngine = "X-Appengine-Remote-Addr"
    // PlatformCloudflare when using Cloudflare's CDN. Trust CF-Connecting-IP for determining
    // the client's IP
    PlatformCloudflare = "CF-Connecting-IP"
)

（2）github.com/gin-gonic/gin/mode.go

源码：https://github.com/gin-gonic/gin/blob/v1.9.0/mode.go#L51-L54

func init() {
    mode := os.Getenv(EnvGinMode)
    SetMode(mode)
}

设置服务的运行模式，默认是 DebugMode

分别有三种模式：DebugMode=0 (开发模式)、releaseCode=1 (生产模式)、testCode=2 (测试模式)

源码：https://github.com/gin-gonic/gin/blob/v1.9.0/mode.go#L15-L25

// EnvGinMode indicates environment name for gin mode.
const EnvGinMode = "GIN_MODE"

const (
    // DebugMode indicates gin mode is debug.
    DebugMode = "debug"
    // ReleaseMode indicates gin mode is release.
    ReleaseMode = "release"
    // TestMode indicates gin mode is test.
    TestMode = "test"
)