英文:
How to pipe an HTTP response to a file in Go?
问题
如何将下面的代码转换为使用流/管道，以便我不需要将全部内容读入内存中？
类似于：
http.Get("http://example.com/").Pipe("./data.txt")
package main
import ("net/http";"io/ioutil")
func main() {
resp, err := http.Get("http://example.com/")
check(err)
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
check(err)
err = ioutil.WriteFile("./data.txt", body, 0666)
check(err)
}
func check(e error) {
if e != nil {
panic(e)
}
}
英文:
How do I convert the below code to use streams/pipes so that I don't need to read the full content into memory?
Something like:
http.Get("http://example.com/").Pipe("./data.txt")
package main
import ("net/http";"io/ioutil")
func main() {
resp, err := http.Get("http://example.com/")
check(err)
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
check(err)
err = ioutil.WriteFile("./data.txt", body, 0666)
check(err)
}
func check(e error) {
if e != nil {
panic(e)
}
}
答案1
得分: 81
io.Copy()怎么样？它的文档可以在这里找到：http://golang.org/pkg/io/#Copy
它非常简单。给它一个io.Reader和一个io.Writer，它会一次拷贝一小块数据（例如不会一次性全部加载到内存中）。
所以你可以尝试写出类似这样的代码：
func main() {
resp, err := http.Get("...")
check(err)
defer resp.Body.Close()
out, err := os.Create("filename.ext")
if err != nil {
// 报错？
}
defer out.Close()
io.Copy(out, resp.Body)
}
我没有测试上面的代码；我只是从你上面的示例中快速拼凑出来的，但如果不是完全正确，也应该很接近。
英文:
How about io.Copy()? Its documentation can be found at: http://golang.org/pkg/io/#Copy
It's pretty simple, though. Give it an io.Reader and an io.Writer and it copies the data over, one small chunk at a time (e.g. not all in memory at once).
So you might try writing something like:
func main() {
resp, err := http.Get("...")
check(err)
defer resp.Body.Close()
out, err := os.Create("filename.ext")
if err != nil {
// panic?
}
defer out.Close()
io.Copy(out, resp.Body)
}
I haven't tested the above; I just hacked it together quickly from your above example, but it should be close if not on the money.
答案2
得分: 8
另一个选项是File.ReadFrom：
package main
import (
"net/http"
"os"
)
func main() {
r, e := http.Get("http://speedtest.lax.hivelocity.net")
if e != nil {
panic(e)
}
defer r.Body.Close()
f, e := os.Create("index.html")
if e != nil {
panic(e)
}
defer f.Close()
f.ReadFrom(r.Body)
}
英文:
Another option is File.ReadFrom:
package main
import (
"net/http"
"os"
)
func main() {
r, e := http.Get("http://speedtest.lax.hivelocity.net")
if e != nil {
panic(e)
}
defer r.Body.Close()
f, e := os.Create("index.html")
if e != nil {
panic(e)
}
defer f.Close()
f.ReadFrom(r.Body)
}
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