golang下载图片，而非预览

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1 前言

网上查询使用html5，a增加属性download和使用表单get，post提交，都是只能预览，根本原因是返回值需要加入头

w.Header().Add("Content-Type", "application/octet-stream")
w.Header().Add("Content-Disposition", "attachment; filename=\""+filename+"\"")

告知浏览器返回值是附件形式下载即可。

2 代码

package DownloadControllerimport (
"fmt"
"net/http"
"strings"
"Project/Utils"
"Project/Server/Download"
)func DownloadController(w http.ResponseWriter, r *http.Request) {defer r.Body.Close()w.Header().Set("Access-Control-Allow-Origin", "*") // 允许访问所有域
w.Header().Add("Access-Control-Allow-Headers", "Content-Type") // header的类型switch r.Method {
case "POST", "GET":
{urlname := r.FormValue("url")if strings.EqualFold(urlname, "") {
resp_json := Utils.GetRespJson(400, "请求参数错误！", nil)
fmt.Fprintln(w, string(resp_json))
return
}filename, content, err := DownloadServer.Download(urlname)w.Header().Add("Content-Type", "application/octet-stream")
w.Header().Add("Content-Disposition", "attachment; filename=\""+filename+"\"")if err != nil {
fmt.Println("Read File Err:", err.Error())
resp_json := Utils.GetRespJson(400, "下载失败！", nil)
fmt.Fprintln(w, string(resp_json))
return
} else {
w.Write(content)
fmt.Println("Download filename=" + filename + " OK")
//resp_json := Utils.GetRespJson(200, "下载成功！", nil)
//fmt.Fprintln(w, string(resp_json))
}
return
}
default:
resp_json := Utils.GetRespJson(400, "错误的请求方式！", nil)
fmt.Fprintln(w, string(resp_json))
return
}}package DownloadServerimport (
"fmt"
"Project/Utils/Config"
"os"
"io/ioutil"
"strings"
"net/url"
"time"
)func Download(urlname string) (filename string, content []byte, err error) {pos1 := strings.LastIndex(urlname,"Resources")
urlname = urlname[pos1:]path := Config.GetValue("project_path") + "/web/"
file, err := os.Open(path + urlname)
if err != nil {
fmt.Println(err)
return
}
defer file.Close()
content, err = ioutil.ReadAll(file)
pos := strings.LastIndex(urlname, "/") + 1
zipNameNew := urlname[pos:]
// 防止中文乱码
timeStr := time.Now().Format("2006010203040506")
filename = url.QueryEscape("Res" + timeStr + "_" + zipNameNew)return
}