"Go" Golang file operations read and write files, upload files, traverse files, delete files

This is a creation in Article, where the information may have evolved or changed.

1. Create and Open
To create a file function:
Func Create (name string) (file *file, err Error)
Func NewFile (fd int, name string) *file
To open a file function:
Func Open (name string) (file *file, err Error)
Func OpenFile (name string, flag int, perm uint32) (file *file, err Error)

2. Writing files
Write file function:
Func (file *file) Write (b []byte) (n int, err Error)
Func (file *file) writeat (b []byte, off Int64) (n int, err Error)
Func (file *file) writestring (S string) (ret int, err Error)

Instance:
Package Main
Import (
"OS"
"FMT"
)
Func Main () {
UserFile: = "Test.txt"
Fout,err: = os. Create (UserFile)
Defer Fout. Close ()
If err! = Nil {
Fmt. Println (Userfile,err)
Return
}
For i:= 0;i<10;i++ {
Fout. WriteString ("www.godeye.org!\r\n")
Fout. Write ([]byte ("www.godeye.org!\r\n"))
}
}

3. Read the file
Read File function:
Func (file *file) Read (b []byte) (n int, err Error)
Func (file *file) readat (b []byte, off Int64) (n int, err Error)
Instance:
Package Main

Import (
"FMT"
"OS"
)

Func Main () {
UserFile: = "Test.txt"
Fin, err: = OS. Open (UserFile)
Defer fin. Close ()
If err! = Nil {
Fmt. Println (UserFile, err)
Return
}
BUF: = Make ([]byte, 1024)
for {
N, _: = Fin. Read (BUF)
if 0 = = n {
Break
}
Os. Stdout.write (Buf[:n])
}
}

4. deleting files
Go language inside Delete file and delete folder is the same function
Func Remove (name string) Error
Instance:
Package Main

Import (
"OS"
)

Func Main () {
UserFile: = "Godeye.txt"
Os. Remove (UserFile)
}

5. Traverse a Folder
Package Main
Import (
"Flag"
"FMT"
"OS"
"Path/filepath"
)

Func getfilelist (path string) {
ERR: = FilePath. Walk (Path, func (path string, f OS). FileInfo, err Error) error {
if f = = nil {
return err
}
If F.isdir () {
return Nil
}
Fmt. Printf (PATH)
return Nil
})
If err! = Nil {
Fmt. Printf ("filepath. Walk () returned%v\n ", err)
}
}
Func Main () {
Getfilelist ("src")
}

6. classic File Upload
Here are 2 files, one is the server handler Upload.go, and the other is the template page upload.html

See Upload.go first.
Package Main

Import (
"FMT"
"Html/template"
"IO"
"Log"
"Net/http"
"OS"
)

var buf []byte

Func Upload (w http. Responsewriter, R *http. Request) {
R.parseform ()
if R.method = = "GET" {
T, err: = template. Parsefiles ("upload.html")
Checkerr (ERR)
T.execute (W, Nil)
} else {
File, handle, err: = R.formfile ("file")
Checkerr (ERR)
F, err: = OS. OpenFile ("./test/" +handle. Filename, OS. O_wronly|os. O_create, 0666)
Io. Copy (f, file)
Checkerr (ERR)
Defer F.close ()
Defer file. Close ()
Fmt. Println ("Upload success")
}
}

Func Checkerr (err error) {
If err! = Nil {
Err. Error ()
}
}

Func Main () {
http. Handlefunc ("/upload", upload)
ERR: = http. Listenandserve (": 8888", nil)
If err! = Nil {
Log. Fatal ("Listenandserve:", err)
}
}