golang几种post方式

用golang进行http请求类型多了，总结备忘一下。

1.普通的post\get请求

　　 var r http.Request
    r.ParseForm()
    r.Form.Add("uuid", orderUUID)
    bodystr := strings.TrimSpace(r.Form.Encode())
    request, err := http.NewRequest("GET", url, strings.NewReader(bodystr))
    if err != nil {
     　　//TODO:
    }
    request.Header.Set("Content-Type", "application/x-www-form-urlencoded")
    request.Header.Set("Connection", "Keep-Alive")

    var resp *http.Response
    resp, err = http.DefaultClient.Do(request)
    if err != nil {
　　　　//TODO:
    }

2. body全部二进制数据流进行post

//body提交二进制数据
func DoBytesPost(url string, data []byte) ([]byte, error) {

    body := bytes.NewReader(data)
    request, err := http.NewRequest(POST_METHOD, url, body)
    if err != nil {
        log.Println("http.NewRequest,[err=%s][url=%s]", err, url)
        return []byte(""), err
    }
    request.Header.Set("Connection", "Keep-Alive")
    var resp *http.Response
    resp, err = http.DefaultClient.Do(request)
    if err != nil {
        log.Println("http.Do failed,[err=%s][url=%s]", err, url)
        return []byte(""), err
    }
    defer resp.Body.Close()
    b, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        log.Println("http.Do failed,[err=%s][url=%s]", err, url)
    }
    return b, err
}

3. 模拟web表单文件上传进行post

func newfileUploadRequest(uri string, params map[string]string, paramName, path string) (*http.Request, error) {
    file, err := os.Open(path)
    if err != nil {
        return nil, err
    }
    defer file.Close()

    body := &bytes.Buffer{}
    writer := multipart.NewWriter(body)
    part, err := writer.CreateFormFile(paramName, path)
    if err != nil {
        return nil, err
    }
    # 这里的io.Copy实现,会把file文件都读取到内存里面，然后当做一个buffer传给NewRequest. 对于大文件来说会占用很多内存
    _, err = io.Copy(part, file)

    for key, val := range params {
        _ = writer.WriteField(key, val)
    }
    err = writer.Close()
    if err != nil {
        return nil, err
    }
    request, err := http.NewRequest("POST", uri, body)
    request.Header.Set("Content-Type", writer.FormDataContentType())
    return request, err
}

下面这种方式，就是传入文件句柄,然后由request copy到socket的缓冲区，而不用全部读取到内存中：

    bodyBuf := bytes.NewBufferString("")
    bodyWriter := multipart.NewWriter(bodyBuf)

    //建立文件的http第一部分数据,文件信息
    _, err := bodyWriter.CreateFormFile(paramName, path)
    if err != nil {
        return nil, err
    }

    //读取文件,当做http第二部分数据
    fh, err := os.Open(path)
    if err != nil {
        return nil, err
    }
    //mulitipart/form-data时,需要获取自己关闭的boundary
    boundary := bodyWriter.Boundary()
    closeBuf := bytes.NewBufferString(fmt.Sprintf("\r\n--%s--\r\n", boundary))

    //建立写入socket的reader对象
    requestReader := io.MultiReader(bodyBuf, fh, closeBuf)

    fi, err := fh.Stat()
    if err != nil {
        return nil, err
    }
    req, err := http.NewRequest("POST", uri, requestReader)
    if err != nil {
        return nil, err
    }
    //设置http头
    req.Header.Add("Content-Type", "multipart/form-data; boundary="+boundary)
    req.ContentLength = fi.Size() + int64(bodyBuf.Len()) + int64(closeBuf.Len())

go package 的实现源码：

http://golang.org/src/io/io.go?s=12247:12307#L340

https://golang.org/src/io/multi.go?h=MultiReader#L31

https://golang.org/src/net/http/transfer.go?h=WriteBody#L199

https://golang.org/src/net/http/request.go?h=write#L366

参考连接：

https://groups.google.com/forum/#!topic/golang-nuts/Zjg5l4nKcQ0