示例如下:
下载文件过程中 生成XXX.download中间文件,下载完成后再重命名为待下载文件XXX
package mainimport (
"crypto/md5"
"errors"
"fmt"
"io"
"io/IoUtil"
"net/http"
"os"
"strconv"
"time"
)
func IsFileExist(filename string,filesize int64) bool {
info,err := os.Stat(filename)
if os.IsNotExist(err) {
fmt.Println(info)
return false
}
if filesize == info.Size() {
fmt.Println("安装包已存在!",info.Name(),info.Size(),info.ModTime())
return true
}
del := os.Remove(filename)
if del != nil {
fmt.Println(del)
}
return false
}
func downloadFile(url string,localPath string,fb func(length,downLen int64)) error {
var (
fsize int64
buf = make([]byte,32*1024)
written int64
)
tmpFilePath := localPath + ".download"
fmt.Println(tmpFilePath)
//创建一个http client
client := new(http.Client)
//client.Timeout = time.Second * 60 //设置超时时间
//get方法获取资源
resp,err := client.Get(url)
if err != nil {
return err
}
//读取服务器返回的文件大小
fsize,err = strconv.ParseInt(resp.Header.Get("Content-Length"),10,32)
if err != nil {
fmt.Println(err)
}
if IsFileExist(localPath,fsize) {
return err
}
fmt.Println("fsize",fsize)
//创建文件
file,err := os.Create(tmpFilePath)
if err != nil {
return err
}
defer file.Close()
if resp.Body == nil {
return errors.New("body is null")
}
defer resp.Body.Close()
//下面是 io.copyBuffer() 的简化版本
for {
//读取bytes
nr,er := resp.Body.Read(buf)
if nr > 0 {
//写入bytes
nw,ew := file.Write(buf[0:nr])
//数据长度大于0
if nw > 0 {
written += int64(nw)
}
//写入出错
if ew != nil {
err = ew
break
}
//读取是数据长度不等于写入的数据长度
if nr != nw {
err = io.ErrShortWrite
break
}
}
if er != nil {
if er != io.EOF {
err = er
}
break
}
//没有错误了快使用 callback
fb(fsize,written)
}
fmt.Println(err)
if err == nil {
file.Close()
err = os.Rename(tmpFilePath,localPath)
fmt.Println(err)
}
return err
}