Golang实现http server提供压缩文件下载功能

func (c *Controller)Download() {
  //...文件信息的产生逻辑
  //
  //rw为responseWriter
  rw := c.Ctx.ResponseWriter
  //规定下载后的文件名
  rw.Header().Set("Content-Disposition", "attachment; filename="+"(文件名字)")
  rw.Header().Set("Content-Description", "File Transfer")
  //标明传输文件类型
  //如果是其他类型，请参照：https://www.runoob.com/http/http-content-type.html
  rw.Header().Set("Content-Type", "application/octet-stream")
  rw.Header().Set("Content-Transfer-Encoding", "binary")
  rw.Header().Set("Expires", "0")
  rw.Header().Set("Cache-Control", "must-revalidate")
  rw.Header().Set("Pragma", "public")
  rw.WriteHeader(http.StatusOK)
  //文件的传输是用byte slice类型，本例子中：b是一个bytes.Buffer，则需调用b.Bytes()
  http.ServeContent(rw, c.Ctx.Request, "(文件名字)", time.Now(), bytes.NewReader(b.Bytes()))
}

  //最内层用bytes.Buffer来进行文件的存储
  var b bytes.Buffer
  //嵌套tar包的writter和gzip包的writer
  gw := gzip.NewWriter(&b)
  tw := tar.NewWriter(gw)


  dataFile := //...文件的产生逻辑，dataFile为File类型
  info, _ := dataFile.Stat()
  header, _ := tar.FileInfoHeader(info, "")
  //下载后当前文件的路径设置
  header.Name = "report" + "/" + header.Name
  err := tw.WriteHeader(header)
  if err != nil {
    utils.LogErrorln(err.Error())
    return
  }
  _, err = io.Copy(tw, dataFile)
  if err != nil {
    utils.LogErrorln(err.Error())
  }
  //...可以继续添加文件
  //tar writer 和 gzip writer的关闭顺序一定不能反
  tw.Close()
  gw.Close()

type myFileInfo struct {
  name string
  data []byte
}

func (mif myFileInfo) Name() string    { return mif.name }
func (mif myFileInfo) Size() int64    { return int64(len(mif.data)) }
func (mif myFileInfo) Mode() os.FileMode { return 0444 }    // Read for all
func (mif myFileInfo) ModTime() time.Time { return time.Time{} } // Return whatever you want
func (mif myFileInfo) IsDir() bool    { return false }
func (mif myFileInfo) Sys() interface{}  { return nil }

type MyFile struct {
  *bytes.Reader
  mif myFileInfo
}

func (mf *MyFile) Close() error { return nil } // Noop, nothing to do

func (mf *MyFile) Readdir(count int) ([]os.FileInfo, error) {
  return nil, nil // We are not a directory but a single file
}

func (mf *MyFile) Stat() (os.FileInfo, error) {
  return mf.mif, nil
}

func testWrite(data map[string]interface{}, taskId string) http.File {
  //最后生成的html，打开html模版
  tempfileP, _ := os.Open("views/traffic/generatePage.html")
  info, _ := tempfileP.Stat()
  html := make([]byte, info.Size())
  _, err := tempfileP.Read(html)
  // 将data数据写入html
  var b bytes.Buffer
  // 创建Json编码器
  encoder := json.NewEncoder(&b)

  err = encoder.Encode(data)
  if err != nil {
    utils.LogErrorln(err.Error())
  }
  
  // 将json数据添加到html模版中
  // 方式为在html模版中插入一个特殊的替换字段，本例中为{Data_Json_Source}
  html = bytes.Replace(html, []byte("{Data_Json_Source}"), b.Bytes(), 1)

  // 将静态文件添加进html
  // 如果是.css,则前后增加<style></style>标签
  // 如果是.js,则前后增加<script><script>标签
  allStaticFiles := make([][]byte, 0)
  // jquery 需要最先进行添加
  tempfilename := "static/report/jquery.min.js"

  tempfileP, _ = os.Open(tempfilename)
  info, _ = os.Stat(tempfilename)
  curFileByte := make([]byte, info.Size())
  _, err = tempfileP.Read(curFileByte)

  allStaticFiles = append(allStaticFiles, []byte("<script>"))
  allStaticFiles = append(allStaticFiles, curFileByte)
  allStaticFiles = append(allStaticFiles, []byte("</script>"))
  //剩下的所有静态文件
  staticFiles, _ := ioutil.ReadDir("static/report/")
  for _, tempfile := range staticFiles {
    if tempfile.Name() == "jquery.min.js" {
      continue
    }
    tempfilename := "static/report/" + tempfile.Name()

    tempfileP, _ := os.Open(tempfilename)
    info, _ := os.Stat(tempfilename)
    curFileByte := make([]byte, info.Size())
    _, err := tempfileP.Read(curFileByte)
    if err != nil {
      utils.LogErrorln(err.Error())
    }
    if isJs, _ := regexp.MatchString(`\.js$`, tempfilename); isJs {
      allStaticFiles = append(allStaticFiles, []byte("<script>"))
      allStaticFiles = append(allStaticFiles, curFileByte)
      allStaticFiles = append(allStaticFiles, []byte("</script>"))
    } else if isCss, _ := regexp.MatchString(`\.css$`, tempfilename); isCss {
      allStaticFiles = append(allStaticFiles, []byte("<style>"))
      allStaticFiles = append(allStaticFiles, curFileByte)
      allStaticFiles = append(allStaticFiles, []byte("</style>"))
    }
    tempfileP.Close()
  }
  
  // 转成http.File格式进行返回
  mf := &MyFile{
    Reader: bytes.NewReader(html),
    mif: myFileInfo{
      name: "report.html",
      data: html,
    },
  }
  var f http.File = mf
  return f
}

func (c *Controller)Download() {
  var b bytes.Buffer
  gw := gzip.NewWriter(&b)

  tw := tar.NewWriter(gw)

  // 生成动态report,并添加进压缩包
  // 调用上文中的testWrite方法
  dataFile := testWrite(responseByRules, strTaskId)
  info, _ := dataFile.Stat()
  header, _ := tar.FileInfoHeader(info, "")
  header.Name = "report_" + strTaskId + "/" + header.Name
  err := tw.WriteHeader(header)
  if err != nil {
    utils.LogErrorln(err.Error())
    return
  }
  _, err = io.Copy(tw, dataFile)
  if err != nil {
    utils.LogErrorln(err.Error())
  }

  tw.Close()
  gw.Close()
  rw := c.Ctx.ResponseWriter
  rw.Header().Set("Content-Disposition", "attachment; filename="+"report_"+strTaskId+".tar.gz")
  rw.Header().Set("Content-Description", "File Transfer")
  rw.Header().Set("Content-Type", "application/octet-stream")
  rw.Header().Set("Content-Transfer-Encoding", "binary")
  rw.Header().Set("Expires", "0")
  rw.Header().Set("Cache-Control", "must-revalidate")
  rw.Header().Set("Pragma", "public")
  rw.WriteHeader(http.StatusOK)
  http.ServeContent(rw, c.Ctx.Request, "report_"+strTaskId+".tar.gz", time.Now(), bytes.NewReader(b.Bytes()))
}

<a href="/traffic/download_indicator" rel="external nofollow" >
   <button style="font-family: 'SimHei';font-size: 14px;font-weight: bold;color: #0d6aad;text-decoration: underline;margin-left: 40px;" type="button" class="btn btn-link">下载报表</button>
</a>