package main

import (

    "bytes"

    "fmt"

    "io"

    "mime/multipart"

    "net/http"

    "os"

)

func postFile(filename string, target_url string) (*http.Response, error) {

    body_buf := bytes.NewBufferString("")

    body_writer := multipart.NewWriter(body_buf)

    // use the body_writer to write the Part headers to the buffer

    _, err := body_writer.CreateFormFile("userfile", filename)

    if err != nil {

        fmt.Println("error writing to buffer")

        return nil, err

    }

    // the file data will be the second part of the body

    fh, err := os.Open(filename)

    if err != nil {

        fmt.Println("error opening file")

        return nil, err

    }

    // need to know the boundary to properly close the part myself.

    boundary := body_writer.Boundary()

    //close_string := fmt.Sprintf("\r\n--%s--\r\n", boundary)

    close_buf := bytes.NewBufferString(fmt.Sprintf("\r\n--%s--\r\n", boundary))

    // use multi-reader to defer the reading of the file data until

    // writing to the socket buffer.

    request_reader := io.MultiReader(body_buf, fh, close_buf)

    fi, err := fh.Stat()

    if err != nil {

        fmt.Printf("Error Stating file: %s", filename)

        return nil, err

    }

    req, err := http.NewRequest("POST", target_url, request_reader)

    if err != nil {

        return nil, err

    }

    // Set headers for multipart, and Content Length

    req.Header.Add("Content-Type", "multipart/form-data; boundary="+boundary)

    req.ContentLength = fi.Size() + int64(body_buf.Len()) + int64(close_buf.Len())

    return http.DefaultClient.Do(req)

}

// sample usage

func main() {

    target_url := "http://localhost:8086/upload"

    filename := "/Users/wei/Downloads/21dian_1.9_10"

    postFile(filename, target_url)

}

参考文章 https://matt.aimonetti.net/posts/2013/07/01/golang-multipart-file-upload-example/ 25

package main

import (

    "bytes"

    "fmt"

    "log"

    "mime/multipart"

    "net/http"

)

// Creates a new file upload http request with optional extra params

func newMultipartRequest(url string, params map[string]string) (*http.Request, error) {

    body := &bytes.Buffer{}

    writer := multipart.NewWriter(body)

    for key, val := range params {

        _ = writer.WriteField(key, val)

    }

    writer.Close()

    return http.NewRequest("POST", url, body)

}

func main() {

    extraParams := map[string]string{

        "title":       "My Document",

        "author":      "zieckey",

        "description": "A document with all the Go programming language secrets",

    }

    request, err := newMultipartRequest("http://127.0.0.1:8091/echo", extraParams)

    if err != nil {

        log.Fatal(err)

    }

    client := &http.Client{}

    resp, err := client.Do(request)

    if err != nil {

        log.Fatal(err)

    } else {

        body := &bytes.Buffer{}

        _, err := body.ReadFrom(resp.Body)

        if err != nil {

            log.Fatal(err)

        }

        resp.Body.Close()

        fmt.Println(resp.StatusCode)

        fmt.Println(resp.Header)

        fmt.Println(body)

    }

}

multipart 的例子

package main

import (

    "bytes"

    "fmt"

    "io"

    "log"

    "mime/multipart"

    "net/http"

    "os"

    "path/filepath"

)

// Creates a new file upload http request with optional extra params

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, filepath.Base(path))

    if err != nil {

        return nil, err

    }

    _, 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.Add("Content-Type", writer.FormDataContentType())

    return request, err

}

func main() {

    path, _ := os.Getwd()

    path += "/test.pdf"

    extraParams := map[string]string{

        "title":       "My Document",

        "author":      "Matt Aimonetti",

        "description": "A document with all the Go programming language secrets",

    }

    request, err := newfileUploadRequest("http://localhost:8086/upload", extraParams, "userfile", "/Users/wei/Downloads/21dian_1.9_10")

    if err != nil {

        log.Fatal(err)

    }

    client := &http.Client{}

    resp, err := client.Do(request)

    if err != nil {

        log.Fatal(err)

    } else {

        body := &bytes.Buffer{}

        _, err := body.ReadFrom(resp.Body)

        if err != nil {

            log.Fatal(err)

        }

        resp.Body.Close()

        fmt.Println(resp.StatusCode)

        fmt.Println(resp.Header)

        fmt.Println(body)

    }

}