Context結(jié)構(gòu)

Context結(jié)構(gòu)定義

type Context struct {
    // responseWriter對(duì)ResponseWriter封裝
    writermem responseWriter

    // http請(qǐng)求及響應(yīng)writer
    Request   *http.Request
    Writer    ResponseWriter

    // 鍵值對(duì)切片類型
    Params   Params

    // HandlerFunc切片類型
    handlers HandlersChain
    index    int8
    fullPath string

    // 當(dāng)前上下文屬于哪個(gè)引擎
    engine *Engine

    // 每個(gè)請(qǐng)求上下文專用鍵值對(duì)
    Keys map[string]interface{}

    // *Error切片類型汤善，Error封裝error類型
    //所有使用當(dāng)前上下文的handlers/middlewares對(duì)應(yīng)的出錯(cuò)信息都存放在這里
    Errors errorMsgs

    // Accepted defines a list of manually accepted formats for content negotiation.
    Accepted []string

    // queryCache use url.ParseQuery cached the param query result from c.Request.URL.Query()
    queryCache url.Values

    // formCache use url.ParseQuery cached PostForm contains the parsed form data from POST, PATCH,
    // or PUT body parameters.
    formCache url.Values
}

url.Values

類型定義

// key類型為string枕赵，value類型為[]string牌柄，一個(gè)key對(duì)應(yīng)多個(gè)value
type Values map[string][]string

方法集

// 通過(guò)key獲取對(duì)應(yīng)的value，如果存在，總會(huì)返回v[key][0]，否則為""
func (v Values) Get(key string) string

// 設(shè)置鍵值對(duì)key/[]string{value}丑慎，若key之前有數(shù)據(jù)，會(huì)被替換掉
func (v Values) Set(key, value string)

// 給key的value列表增加數(shù)據(jù)value
func (v Values) Add(key, value string)

// 刪除key及對(duì)應(yīng)的所有values
func (v Values) Del(key string)

有HTTP請(qǐng)求時(shí)瓤摧，gin處理流程：

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)
}

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
    }
    rPath = cleanPath(rPath)

    // 通過(guò)給定的HTTP請(qǐng)求方法找到方法樹(shù)
    t := engine.trees
    for i, tl := 0, len(t); i < tl; i++ {
        if t[i].method != httpMethod {
            continue
        }
        root := t[i].root
        // 找到樹(shù)中的路由
        value := root.getValue(rPath, c.Params, unescape)
        if value.handlers != nil {
            c.handlers = value.handlers
            c.Params = value.params
            c.fullPath = value.fullPath
            c.Next()
            c.writermem.WriteHeaderNow()
            return
        }
        if httpMethod != "CONNECT" && rPath != "/" {
            if value.tsr && engine.RedirectTrailingSlash {
                redirectTrailingSlash(c)
                return
            }
            if engine.RedirectFixedPath && redirectFixedPath(c, root, engine.RedirectFixedPath) {
                return
            }
        }
        break
    }

    if engine.HandleMethodNotAllowed {
        for _, tree := range engine.trees {
            if tree.method == httpMethod {
                continue
            }
            if value := tree.root.getValue(rPath, nil, unescape); value.handlers != nil {
                c.handlers = engine.allNoMethod
                serveError(c, http.StatusMethodNotAllowed, default405Body)
                return
            }
        }
    }
    c.handlers = engine.allNoRoute
    serveError(c, http.StatusNotFound, default404Body)
}