ioutils.ReadAll()会清空对应的reader

解决办法：

//copy first, or Boby will be emptyreqBytes, err := ioutil.ReadAll(c.Request.Body)if err != nil {log.Error("fail to read requset data")return 0, err}log.Infof("%s", reqBytes)buf := bytes.NewBuffer(reqBytes)c.Request.Body = ioutil.NopCloser(buf)

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原因分析：

http://stackoverflow.com/questions/30910487/why-an-io-reader-after-read-it-became-empty-in-golang

Reading from a bytes.Buffer drains or consumes the bytes that were read. This means if you try to read again those will not be returned.

Buffer.Bytes() returns the unread portion of the buffer so it is the expected result for you to see 0 length after everything has been read (this is exactly what ioutil.ReadAll() does).

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What if you just want to "peek" and not really "read" bytes?

There is no "peek" functionality in bytes.Buffer. The easiest would be to get the bytes of the buffer, and construct another bytes.Buffer from it and read from the new buffer.

It could look something like this:

func peek(buf *bytes.Buffer, b []byte) (int, error) {    buf2 := bytes.NewBuffer(buf.Bytes())    return buf2.Read(b)}

实现代码分析: http://www.cnphp6.com/archives/110001

解决思路来源：

Reading body of http.Request without modifying request state?

http://stackoverflow.com/questions/23070876/reading-body-of-http-request-without-modifying-request-state