Golang Http Server Download File

本来是很简单的代码，如下图

package main

import (
   "encoding/csv"
   "fmt"
   "net/http"
)

func getCsvFile(w http.ResponseWriter, r *http.Request) {
   var (
       csvHeader = []string{"name", "age", "gender"}
       records   = [][]string{
           {"X", "10", "M"},
           {"Y", "11", "M"},
           {"Z", "12", "M"},
       }
   )
   w.Header().Set("Content-Type", "application/octet-stream")
   w.Header().Set("Content-Disposition", fmt.Sprintf("attachment;filename=%s.csv", "result"))
   w.Header().Set("Content-Transfer-Encoding", "binary")
   w.Header().Set("Expires", "0")
   w.WriteHeader(http.StatusOK)
   f := csv.NewWriter(w)
   _ = f.Write(csvHeader)
   _ = f.WriteAll(records)
   f.Flush()
}

func main() {
   http.HandleFunc("/api/csv/download", getCsvFile)
   _ = http.ListenAndServe(":11111", nil)
}

在浏览器输入 127.0.0.1:11111/api/csv/download，就会下载一份 result.csv 文件。

坑

原本很简单的代码踩坑
把 w.WriteHeader(http.StatusOK) 放到 w.Header().Set() 之前就会失败，直接显示 response 的内容。WHY...没看源码，唔知道