func GenerateRequestBody(c *gin.Context) string {
	body, err := c.GetRawData() // 讀取 request body 的內容
	if err != nil {
		body = utils.StringToBytes("failed to get request body")
	}
	c.Request.Body = ioutil.NopCloser(bytes.NewBuffer(body)) // 創(chuàng)建 io.ReadCloser 對象傳給 request body
	return utils.BytesToString(body) // 返回 request body 的值
}

// GetRawData returns stream data.
func (c *Context) GetRawData() ([]byte, error) {
	return ioutil.ReadAll(c.Request.Body)
}

// NopCloser returns a ReadCloser with a no-op Close method wrapping
// the provided Reader r.
//
// As of Go 1.16, this function simply calls io.NopCloser.
func NopCloser(r io.Reader) io.ReadCloser {
	return io.NopCloser(r)
}

// NopCloser returns a ReadCloser with a no-op Close method wrapping
// the provided Reader r.
func NopCloser(r Reader) ReadCloser {
	return nopCloser{r}
}
type nopCloser struct {
	Reader
}
func (nopCloser) Close() error { return nil }

package main
import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
)
func main() {
	resp, _ := doGet("http://www.baidu.com")
	defer resp.Body.Close() //go的特殊語法，main函數執(zhí)行結束前會執(zhí)行 resp.Body.Close()
	fmt.Println(resp.StatusCode)          //有http的響應碼輸出
	if resp.StatusCode == http.StatusOK { //如果響應碼為200
		body, err := ioutil.ReadAll(resp.Body) //把響應的body讀出
		if err != nil {                        //如果有異常
			fmt.Println(err) //把異常打印
			log.Fatal(err)   //日志
		}
		fmt.Println(string(body)) //把響應的文本輸出到console
	}
}
/**
  以GET的方式請求
  **/
func doGet(url string) (r *http.Response, e error) {
	resp, err := http.Get(url)
	if err != nil {
		fmt.Println(resp.StatusCode)
		fmt.Println(err)
		log.Fatal(err)
	}
	return resp, err
}

bodyBytes, _ := ioutil.ReadAll(req.Body)
req.Body.Close()  //  這里調用Close
req.Body = ioutil.NopCloser(bytes.NewBuffer(bodyBytes))

// Serve a new connection.
func (c *conn) serve(ctx context.Context) {
	...
	for {
		w, err := c.readRequest(ctx) // 讀取 request 內容
		...
		}
	...
	// HTTP cannot have multiple simultaneous active requests.[*]
	// Until the server replies to this request, it can't read another,
	// so we might as well run the handler in this goroutine.
	// [*] Not strictly true: HTTP pipelining. We could let them all process
	// in parallel even if their responses need to be serialized.
	// But we're not going to implement HTTP pipelining because it
	// was never deployed in the wild and the answer is HTTP/2.
	inFlightResponse = w
	serverHandler{c.server}.ServeHTTP(w, w.req) // 處理請求
	inFlightResponse = nil
	w.cancelCtx()
	if c.hijacked() {
		return
	}
	w.finishRequest() // 關閉請求
	...
	}

func (w *response) finishRequest() {
	...
	// Close the body (regardless of w.closeAfterReply) so we can
	// re-use its bufio.Reader later safely.
	w.reqBody.Close() // 關閉 request body ???，在這里？
	...
}

// A response represents the server side of an HTTP response.
type response struct {
	...
	req              *Request // request for this response
	reqBody          io.ReadCloser
	...
}

// Read next request from connection.
func (c *conn) readRequest(ctx context.Context) (w *response, err error) {
	...
	req, err := readRequest(c.bufr)
	if err != nil {
		if c.r.hitReadLimit() {
			return nil, errTooLarge
		}
		return nil, err
	}
	...
	w = &response{
		...
		req:           req,
		reqBody:       req.Body,
		...
	}
	...
}

func GenerateRequestBody(c *gin.Context) string {
	body, err := c.GetRawData() // 讀取 request body 的內容
	if err != nil {
		body = utils.StringToBytes("failed to get request body")
	}
	c.Request.Body = ioutil.NopCloser(bytes.NewBuffer(body)) // 創(chuàng)建 io.ReadCloser 對象傳給 request body
	return utils.BytesToString(body) // 返回 request body 的值
}

func ginRequestBodyBuffer() gin.HandlerFunc {
	return func(c *gin.Context) {
		var b *RequestBodyBuff
		// 創(chuàng)建緩存對象
		b = bodyBufferPool.Get().(*RequestBodyBuff)
		b.bodyBuf.Reset()
		c.Set(ConstRequestBodyBufferKey, b)
		// 下一個請求
		c.Next()
		// 歸還緩存對象
		if o, ok := c.Get(ConstRequestBodyBufferKey); ok {
			b = o.(*RequestBodyBuff)
			b.bodyBuf.Reset()                     // bytes.Buffer 要 reset，但是 slice 就不能，這個做 io.CopyBuffer 用的
			c.Set(ConstRequestBodyBufferKey, nil) // 釋放指向 RequestBodyBuff 對象
			bodyBufferPool.Put(o)                 // 歸還對象
			c.Request.Body = nil                  // 釋放指向創(chuàng)建的 io.NopCloser 對象
		}
	}
}

func GenerateRequestBody(c *gin.Context) string {
	var b *RequestBodyBuff
	if o, ok := c.Get(ConstRequestBodyBufferKey); ok {
		b = o.(*RequestBodyBuff)
	} else {
		b = newRequestBodyBuff()
	}
	body, err := boostio.ReadAllWithBuffer(c.Request.Body, b.swapBuf) // 讀取 request body 的內容，此時 body 的 []byte 是全新的一個數據 copy
	if err != nil {
		body = utils.StringToBytes("failed to get request body")
		boost.Logger.Errorw(utils.BytesToString(body), "error", err)
	}
	_, err = b.bodyBuf.Write(body) // 把內容重新寫入 bytes.Buffer
	if err != nil {
		c.Request.Body = ioutil.NopCloser(bytes.NewBuffer(body))
		boost.Logger.Errorw(utils.BytesToString(body), "error", err)
	} else {
		c.Request.Body = ioutil.NopCloser(b.bodyBuf)
	}
	return utils.BytesToString(body)
}

while true;do curl -i http://127.0.0.1:8080/yy/; done