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update the code style

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This commit is contained in:
astaxie
2015-04-02 13:22:13 +08:00
committed by James Miranda
parent 7fda55b543
commit efb458cd1b
1 changed files with 119 additions and 105 deletions
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en/04.5.md
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@@ -4,58 +4,67 @@ Suppose you have a website like Instagram and you want users to upload their bea
You have to add property `enctype` to the form that you want to use for uploading photos. There are three possible values for this property: You have to add property `enctype` to the form that you want to use for uploading photos. There are three possible values for this property:
application/x-www-form-urlencoded Transcode all characters before uploading (default). ```
multipart/form-data No transcoding. You must use this value when your form has file upload controls. application/x-www-form-urlencoded Transcode all characters before uploading (default).
text/plain Convert spaces to "+", but no transcoding for special characters. multipart/form-data No transcoding. You must use this value when your form has file upload controls.
text/plain Convert spaces to "+", but no transcoding for special characters.
```
Therefore, the HTML content of a file upload form should look like this: Therefore, the HTML content of a file upload form should look like this:
<html> ```
<head> <html>
<title>Upload file</title> <head>
</head> <title>Upload file</title>
<body> </head>
<form enctype="multipart/form-data" action="http://127.0.0.1:9090/upload" method="post"> <body>
<input type="file" name="uploadfile" /> <form enctype="multipart/form-data" action="http://127.0.0.1:9090/upload" method="post">
<input type="hidden" name="token" value="{{.}}"/> <input type="file" name="uploadfile" />
<input type="submit" value="upload" /> <input type="hidden" name="token" value="{{.}}"/>
</form> <input type="submit" value="upload" />
</body> </form>
</html> </body>
</html>
```
We need to add a function on the server side to handle this form. We need to add a function on the server side to handle this form.
http.HandleFunc("/upload", upload) ```
http.HandleFunc("/upload", upload)
// upload logic // upload logic
func upload(w http.ResponseWriter, r *http.Request) { func upload(w http.ResponseWriter, r *http.Request) {
fmt.Println("method:", r.Method) fmt.Println("method:", r.Method)
if r.Method == "GET" { if r.Method == "GET" {
crutime := time.Now().Unix() crutime := time.Now().Unix()
h := md5.New() h := md5.New()
io.WriteString(h, strconv.FormatInt(crutime, 10)) io.WriteString(h, strconv.FormatInt(crutime, 10))
token := fmt.Sprintf("%x", h.Sum(nil)) token := fmt.Sprintf("%x", h.Sum(nil))
t, _ := template.ParseFiles("upload.gtpl")
t.Execute(w, token)
} else {
r.ParseMultipartForm(32 << 20)
file, handler, err := r.FormFile("uploadfile")
if err != nil {
fmt.Println(err)
return
}
defer file.Close()
fmt.Fprintf(w, "%v", handler.Header)
f, err := os.OpenFile("./test/"+handler.Filename, os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
fmt.Println(err)
return
}
defer f.Close()
io.Copy(f, file)
}
}
```
t, _ := template.ParseFiles("upload.gtpl")
t.Execute(w, token)
} else {
r.ParseMultipartForm(32 << 20)
file, handler, err := r.FormFile("uploadfile")
if err != nil {
fmt.Println(err)
return
}
defer file.Close()
fmt.Fprintf(w, "%v", handler.Header)
f, err := os.OpenFile("./test/"+handler.Filename, os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
fmt.Println(err)
return
}
defer f.Close()
io.Copy(f, file)
}
}
As you can see, we need to call `r.ParseMultipartForm` for uploading files. The function `maxMemory` argument. After you call `ParseMultipartForm`, the file will be saved in the server memory with `maxMemory` size. If the file size is larger than `maxMemory`, the rest of the data will be saved in a system temporary file. You can use `r.FormFile` to get the file handle and use `io.Copy` to save to your file system. As you can see, we need to call `r.ParseMultipartForm` for uploading files. The function `maxMemory` argument. After you call `ParseMultipartForm`, the file will be saved in the server memory with `maxMemory` size. If the file size is larger than `maxMemory`, the rest of the data will be saved in a system temporary file. You can use `r.FormFile` to get the file handle and use `io.Copy` to save to your file system.
@@ -69,11 +78,13 @@ We use three steps for uploading files as follows:
The file handler is the `multipart.FileHeader`. It uses the following struct: The file handler is the `multipart.FileHeader`. It uses the following struct:
type FileHeader struct { ```
Filename string type FileHeader struct {
Header textproto.MIMEHeader Filename string
// contains filtered or unexported fields Header textproto.MIMEHeader
} // contains filtered or unexported fields
}
```
![](images/4.5.upload2.png?raw=true) ![](images/4.5.upload2.png?raw=true)
@@ -83,65 +94,68 @@ Figure 4.5 Print information on server after receiving file.
I showed an example of using a form to a upload a file. We can impersonate a client form to upload files in Go as well. I showed an example of using a form to a upload a file. We can impersonate a client form to upload files in Go as well.
package main ```
package main
import ( import (
"bytes" "bytes"
"fmt" "fmt"
"io" "io"
"io/ioutil" "io/ioutil"
"mime/multipart" "mime/multipart"
"net/http" "net/http"
"os" "os"
) )
func postFile(filename string, targetUrl string) error { func postFile(filename string, targetUrl string) error {
bodyBuf := &bytes.Buffer{} bodyBuf := &bytes.Buffer{}
bodyWriter := multipart.NewWriter(bodyBuf) bodyWriter := multipart.NewWriter(bodyBuf)
// this step is very important // this step is very important
fileWriter, err := bodyWriter.CreateFormFile("uploadfile", filename) fileWriter, err := bodyWriter.CreateFormFile("uploadfile", filename)
if err != nil { if err != nil {
fmt.Println("error writing to buffer") fmt.Println("error writing to buffer")
return err return err
} }
// open file handle // open file handle
fh, err := os.Open(filename) fh, err := os.Open(filename)
if err != nil { if err != nil {
fmt.Println("error opening file") fmt.Println("error opening file")
return err return err
} }
//iocopy //iocopy
_, err = io.Copy(fileWriter, fh) _, err = io.Copy(fileWriter, fh)
if err != nil { if err != nil {
return err return err
} }
contentType := bodyWriter.FormDataContentType() contentType := bodyWriter.FormDataContentType()
bodyWriter.Close() bodyWriter.Close()
resp, err := http.Post(targetUrl, contentType, bodyBuf) resp, err := http.Post(targetUrl, contentType, bodyBuf)
if err != nil { if err != nil {
return err return err
} }
defer resp.Body.Close() defer resp.Body.Close()
resp_body, err := ioutil.ReadAll(resp.Body) resp_body, err := ioutil.ReadAll(resp.Body)
if err != nil { if err != nil {
return err return err
} }
fmt.Println(resp.Status) fmt.Println(resp.Status)
fmt.Println(string(resp_body)) fmt.Println(string(resp_body))
return nil return nil
} }
// sample usage
func main() {
target_url := "http://localhost:9090/upload"
filename := "./astaxie.pdf"
postFile(filename, target_url)
}
```
// sample usage
func main() {
target_url := "http://localhost:9090/upload"
filename := "./astaxie.pdf"
postFile(filename, target_url)
}
The above example shows you how to use a client to upload files. It uses `multipart.Write` to write files into cache and sends them to the server through the POST method. The above example shows you how to use a client to upload files. It uses `multipart.Write` to write files into cache and sends them to the server through the POST method.