假如让你来设计group api, 你该怎么设计呢？
group api 和普通api的区别在于前缀不同，如果group api的版本为v1.0 那么相对应的url为/v1.0/xxx, 如果是普通api的话那么api相对应的版本为/xxx
在gin web framework 中设计的原则也是以相对路径来区分。
// RouterGroup is used internally to configure router, a RouterGroup is associated with
// a prefix and an array of handlers (middleware).
type RouterGroup struct {
Handlers HandlersChain #处理函数
basePath string #相对路径
engine *Engine #存在哪个engine上
root bool #基于基树判断是否为root
}
先看gin中group 的添加规则：
router := gin.New()
users := router.Group("/users")
先看gin.New()默认的basePath是什么。
// New returns a new blank Engine instance without any middleware attached.
// By default the configuration is:
// - RedirectTrailingSlash: true
// - RedirectFixedPath: false
// - HandleMethodNotAllowed: false
// - ForwardedByClientIP: true
// - UseRawPath: false
// - UnescapePathValues: true
func New() *Engine {
debugPrintWARNINGNew()
engine := &Engine{
RouterGroup: RouterGroup{
Handlers: nil,
basePath: "/", #默认为“/”
root: true,
},
FuncMap: template.FuncMap{},
RedirectTrailingSlash: true,
RedirectFixedPath: false,
HandleMethodNotAllowed: false,
ForwardedByClientIP: true,
AppEngine: defaultAppEngine,
UseRawPath: false,
UnescapePathValues: true,
MaxMultipartMemory: defaultMultipartMemory,
trees: make(methodTrees, 0, 9),
delims: render.Delims{Left: "{{", Right: "}}"},
secureJsonPrefix: "while(1);",
}
engine.RouterGroup.engine = engine
engine.pool.New = func() interface{} {
return engine.allocateContext()
}
return engine
}
查看router.Group("/users") 的调用
// Group creates a new router group. You should add all the routes that have common middlewares or the same path prefix.
// For example, all the routes that use a common middleware for authorization could be grouped.
func (group *RouterGroup) Group(relativePath string, handlers ...HandlerFunc) *RouterGroup {
return &RouterGroup{
Handlers: group.combineHandlers(handlers),
basePath: group.calculateAbsolutePath(relativePath), #根据relativePath这个参数，计算basePath
engine: group.engine,
}
}
查看group.calculateAbsolutePath(relativePath) 的调用
func (group *RouterGroup) calculateAbsolutePath(relativePath string) string {
return joinPaths(group.basePath, relativePath)
}
再查看joinPaths的实现
func joinPaths(absolutePath, relativePath string) string {
if relativePath == "" { #如果没有relativePath 直接返回absolutePath,默认为“/”
return absolutePath
}
#处理最后的“/”
finalPath := path.Join(absolutePath, relativePath)
appendSlash := lastChar(relativePath) == '/' && lastChar(finalPath) != '/'
if appendSlash {
return finalPath + "/"
}
return finalPath
}