特性
- 中间件抽象支持: handlersChain
- 简介的API抽象使用: gin.Context
- 强大的路由解析支持: radix-tree 路由树
Gin 对 net/http的封装·
gin的 gin.Engine 是net/http的 Handler ，使用net/http提供的http服务，由实现路由注册匹配、请求链路处理
Gin 的 API
- 构造
gin.Engine实例:gin.Default - 路由组注册中间件:
Engine.Use - 路由组注册
GET/POST方法下的handler:Engine.GET/Engine.POST - 路由组组织代码:
Engine.Group - 启动·server:
Engine.Run
gin.Engine 结构
本质上是一个http Handler （实现了HTPServe方法）
type Engine struct {
RouterGroup
// RedirectTrailingSlash enables automatic redirection if the current route can't be matched but a
// handler for the path with (without) the trailing slash exists.
RedirectTrailingSlash bool
// RedirectFixedPath if enabled, the router tries to fix the current request path, if no
// handle is registered for it.
// First superfluous path elements like ../ or // are removed.
// Afterwards the router does a case-insensitive lookup of the cleaned path.
// If a handle can be found for this route, the router makes a redirection
// to the corrected path with status code 301 for GET requests and 307 for
// all other request methods.
// For example /FOO and /..//Foo could be redirected to /foo.
// RedirectTrailingSlash is independent of this option.
RedirectFixedPath bool
// HandleMethodNotAllowed if enabled, the router checks if another method is allowed for the
HandleMethodNotAllowed bool
// ForwardedByClientIP if enabled, client IP will be parsed from the request's headers that
ForwardedByClientIP bool
// AppEngine was deprecated.
AppEngine bool
// UseRawPath if enabled, the url.RawPath will be used to find parameters.
UseRawPath bool
// UnescapePathValues if true, the path value will be unescaped.
UnescapePathValues bool
// RemoveExtraSlash a parameter can be parsed from the URL even with extra slashes.
RemoveExtraSlash bool
// RemoteIPHeaders list of headers used to obtain the client IP when
RemoteIPHeaders []string
// TrustedPlatform if set to a constant of value gin.Platform*, trusts the headers set by
TrustedPlatform string
// MaxMultipartMemory value of 'maxMemory' param that is given to http.Request's ParseMultipartForm
MaxMultipartMemory int64
// UseH2C enable h2c support.
UseH2C bool
// ContextWithFallback enable fallback Context.Deadline(), Context.Done(), Context.Err() and Context.Value() when Context.Request.Context() is not nil.
ContextWithFallback bool
delims render.Delims
secureJSONPrefix string
HTMLRender render.HTMLRender
FuncMap template.FuncMap
allNoRoute HandlersChain
allNoMethod HandlersChain
noRoute HandlersChain
noMethod HandlersChain
pool sync.Pool
trees methodTrees
maxParams uint16
maxSections uint16
trustedProxies []string
trustedCIDRs []*net.IPNet
}
RouterGroup
type RouterGroup struct {
Handlers HandlersChain
basePath string
engine *Engine
root bool
}RouterGroup 将前缀和处理链联系起来 bool 表示是否是前缀树的根节点 Handlers 是处理函数链路
gin.Default
- gin.Default
func Default(opts ...OptionFunc) *Engine {
debugPrintWARNINGDefault()
engine := New()
engine.Use(Logger(), Recovery())
return engine.With(opts...)
}- New
func New(opts ...OptionFunc) *Engine {
debugPrintWARNINGNew()
engine := &Engine{
RouterGroup: RouterGroup{
Handlers: nil,
basePath: "/",
root: true,
},
FuncMap: template.FuncMap{},
RedirectTrailingSlash: true,
RedirectFixedPath: false,
HandleMethodNotAllowed: false,
ForwardedByClientIP: true,
RemoteIPHeaders: []string{"X-Forwarded-For", "X-Real-IP"},
TrustedPlatform: defaultPlatform,
UseRawPath: false,
RemoveExtraSlash: false,
UnescapePathValues: true,
MaxMultipartMemory: defaultMultipartMemory,
trees: make(methodTrees, 0, 9),
delims: render.Delims{Left: "{{", Right: "}}"},
secureJSONPrefix: "while(1);",
trustedProxies: []string{"0.0.0.0/0", "::/0"},
trustedCIDRs: defaultTrustedCIDRs,
}
engine.RouterGroup.engine = engine
engine.pool.New = func() any {
return engine.allocateContext(engine.maxParams)
}
return engine.With(opts...)
}Engine.Run
func (engine *Engine) Run(addr ...string) (err error) {
defer func() { debugPrintError(err) }()
if engine.isUnsafeTrustedProxies() {
debugPrint("[WARNING] You trusted all proxies, this is NOT safe. We recommend you to set a value.\n" +
"Please check https://pkg.go.dev/github.com/gin-gonic/gin#readme-don-t-trust-all-proxies for details.")
}
address := resolveAddress(addr)
debugPrint("Listening and serving HTTP on %s\n", address)
err = http.ListenAndServe(address, engine.Handler())
return
}可以看到gin通过
net/http来实现HTTP服务
Engine的ServeHTTP方法
func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
c := engine.pool.Get().(*Context)
c.writermem.reset(w)
c.Request = req
c.reset()
engine.handleHTTPRequest(c)
engine.pool.Put(c)
}通过Context pool 中获取Context 逻辑实现在
Engine.handleHTTPRequest
Engine的handleHTTPRequest方法
func (engine *Engine) handleHTTPRequest(c *Context) {
httpMethod := c.Request.Method
rPath := c.Request.URL.Path
unescape := false
if engine.UseRawPath && len(c.Request.URL.RawPath) > 0 {
rPath = c.Request.URL.RawPath
unescape = engine.UnescapePathValues
}
if engine.RemoveExtraSlash {
rPath = cleanPath(rPath)
}
// Find root of the tree for the given HTTP method
t := engine.trees
for i, tl := 0, len(t); i < tl; i++ {
if t[i].method != httpMethod {
continue
}
root := t[i].root
// Find route in tree
value := root.getValue(rPath, c.params, c.skippedNodes, unescape)
if value.params != nil {
c.Params = *value.params
}
if value.handlers != nil {
c.handlers = value.handlers
c.fullPath = value.fullPath
c.Next()
c.writermem.WriteHeaderNow()
return
}
if httpMethod != http.MethodConnect && rPath != "/" {
if value.tsr && engine.RedirectTrailingSlash {
redirectTrailingSlash(c)
return
}
if engine.RedirectFixedPath && redirectFixedPath(c, root, engine.RedirectFixedPath) {
return
}
}
break
}
if engine.HandleMethodNotAllowed {
// According to RFC 7231 section 6.5.5, MUST generate an Allow header field in response
// containing a list of the target resource's currently supported methods.
allowed := make([]string, 0, len(t)-1)
for _, tree := range engine.trees {
if tree.method == httpMethod {
continue
}
if value := tree.root.getValue(rPath, nil, c.skippedNodes, unescape); value.handlers != nil {
allowed = append(allowed, tree.method)
}
}
if len(allowed) > 0 {
c.handlers = engine.allNoMethod
c.writermem.Header().Set("Allow", strings.Join(allowed, ", "))
serveError(c, http.StatusMethodNotAllowed, default405Body)
return
}
}
c.handlers = engine.allNoRoute
serveError(c, http.StatusNotFound, default404Body)
}根据Method和URL来匹配相应的handlersChain，然后调用Context.Next执行对应Handlers 所有元信息都由Context携带
Context.Next方法
func (c *Context) Next() {
c.index++
for c.index < int8(len(c.handlers)) {
c.handlers[c.index](c)
c.index++
}
}执行相应方法完成服务响应