Golang创建表单实现文件读写操作时遇到错误怎么解决
Golang创建表单实现文件读写操作时遇到错误怎么解决 这是我的代码
package main
import (
"fmt"
"html/template"
"io/ioutil"
"net/http"
"os"
"path/filepath"
)
var tpl *template.Template
func inti() {
tpl = template.Must(template.ParseGlob("templates/*"))
}
func main() {
http.HandleFunc("/", foo)
http.Handle("/favicon.ico", http.NotFoundHandler())
http.ListenAndServe(":8080", nil)
}
// check error
func errorCheck(err error, w http.ResponseWriter) {
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
}
//foo call for route “/”
func foo(w http.ResponseWriter, req *http.Request) {
var s string
fmt.Println(req.Method)
if req.Method == http.MethodPost {
//open...
f, h, err := req.FormFile("q")
errorCheck(err, w)
defer f.Close()
fmt.Println("\nfile name: ", f, "\nheader:", h, "\nerror:", err)
bs, err := ioutil.ReadAll(f)
errorCheck(err, w)
s = string(bs)
//store on server...
dst, err := os.Create(filepath.Join("./user/", h.Filename))
errorCheck(err, w)
defer dst.Close()
_, err = dst.Write(bs)
errorCheck(err, w)
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
tpl.ExecuteTemplate(w, "index.gohtml", s)
}
这是我遇到的错误
2020/08/01 18:03:17 http: panic serving [::1]:36012: runtime error: invalid memory address or nil pointer dereference
goroutine 19 [running]:
net/http.(*conn).serve.func1(0xc0000c0fa0)
/usr/local/go/src/net/http/server.go:1772 +0x139
panic(0x780b80, 0xadc810)
/usr/local/go/src/runtime/panic.go:975 +0x3e3
html/template.(*Template).lookupAndEscapeTemplate(0x0, 0x7e6e17, 0xc, 0x0, 0x0, 0x0)
/usr/local/go/src/html/template/template.go:144 +0x4a
html/template.(*Template).ExecuteTemplate(0x0, 0x86bde0, 0xc0000fc0e0, 0x7e6e17, 0xc, 0x761160, 0xb18220, 0xc000047b78, 0x6ffdda)
/usr/local/go/src/html/template/template.go:133 +0x43
main.foo(0x871940, 0xc0000fc0e0, 0xc000118000)
/home/niteesh/Desktop/goworkspace/src/github.com/egnimos/golang_WEB_HTTP_package/passing_data/form_file_write/main.go:73 +0x23a
net/http.HandlerFunc.ServeHTTP(0x801810, 0x871940, 0xc0000fc0e0, 0xc000118000)
/usr/local/go/src/net/http/server.go:2012 +0x44
net/http.(*ServeMux).ServeHTTP(0xaec780, 0x871940, 0xc0000fc0e0, 0xc000118000)
/usr/local/go/src/net/http/server.go:2387 +0x1a5
net/http.serverHandler.ServeHTTP(0xc0000fc000, 0x871940, 0xc0000fc0e0, 0xc000118000)
/usr/local/go/src/net/http/server.go:2807 +0xa3
net/http.(*conn).serve(0xc0000c0fa0, 0x8722c0, 0xc0000c2300)
/usr/local/go/src/net/http/server.go:1895 +0x86c
created by net/http.(*Server).Serve
/usr/local/go/src/net/http/server.go:2933 +0x35c
2020/08/01 18:03:17 http: panic serving [::1]:36014: runtime error: invalid memory address or nil pointer dereference
goroutine 20 [running]:
net/http.(*conn).serve.func1(0xc0000c1040)
/usr/local/go/src/net/http/server.go:1772 +0x139
panic(0x780b80, 0xadc810)
/usr/local/go/src/runtime/panic.go:975 +0x3e3
html/template.(*Template).lookupAndEscapeTemplate(0x0, 0x7e6e17, 0xc, 0x0, 0x0, 0x0)
/usr/local/go/src/html/template/template.go:144 +0x4a
html/template.(*Template).ExecuteTemplate(0x0, 0x86bde0, 0xc00019c000, 0x7e6e17, 0xc, 0x761160, 0xb18220, 0xc00004bb78, 0x6ffdda)
/usr/local/go/src/html/template/template.go:133 +0x43
main.foo(0x871940, 0xc00019c000, 0xc00006e000)
/home/niteesh/Desktop/goworkspace/src/github.com/egnimos/golang_WEB_HTTP_package/passing_data/form_file_write/main.go:73 +0x23a
net/http.HandlerFunc.ServeHTTP(0x801810, 0x871940, 0xc00019c000, 0xc00006e000)
/usr/local/go/src/net/http/server.go:2012 +0x44
net/http.(*ServeMux).ServeHTTP(0xaec780, 0x871940, 0xc00019c000, 0xc00006e000)
/usr/local/go/src/net/http/server.go:2387 +0x1a5
net/http.serverHandler.ServeHTTP(0xc0000fc000, 0x871940, 0xc00019c000, 0xc00006e000)
/usr/local/go/src/net/http/server.go:2807 +0xa3
net/http.(*conn).serve(0xc0000c1040, 0x8722c0, 0xc00005e040)
/usr/local/go/src/net/http/server.go:1895 +0x86c
created by net/http.(*Server).Serve
/usr/local/go/src/net/http/server.go:2933 +0x35c
2020/08/01 18:03:17 http: panic serving [::1]:36016: runtime error: invalid memory address or nil pointer dereference
goroutine 5 [running]:
net/http.(*conn).serve.func1(0xc000072000)
/usr/local/go/src/net/http/server.go:1772 +0x139
panic(0x780b80, 0xadc810)
/usr/local/go/src/runtime/panic.go:975 +0x3e3
html/template.(*Template).lookupAndEscapeTemplate(0x0, 0x7e6e17, 0xc, 0x0, 0x0, 0x0)
/usr/local/go/src/html/template/template.go:144 +0x4a
html/template.(*Template).ExecuteTemplate(0x0, 0x86bde0, 0xc00007c000, 0x7e6e17, 0xc, 0x761160, 0xb18220, 0xc00004cb78, 0x6ffdda)
/usr/local/go/src/html/template/template.go:133 +0x43
main.foo(0x871940, 0xc00007c000, 0xc00006e100)
/home/niteesh/Desktop/goworkspace/src/github.com/egnimos/golang_WEB_HTTP_package/passing_data/form_file_write/main.go:73 +0x23a
net/http.HandlerFunc.ServeHTTP(0x801810, 0x871940, 0xc00007c000, 0xc00006e100)
/usr/local/go/src/net/http/server.go:2012 +0x44
net/http.(*ServeMux).ServeHTTP(0xaec780, 0x871940, 0xc00007c000, 0xc00006e100)
/usr/local/go/src/net/http/server.go:2387 +0x1a5
net/http.serverHandler.ServeHTTP(0xc0000fc000, 0x871940, 0xc00007c000, 0xc00006e100)
/usr/local/go/src/net/http/server.go:2807 +0xa3
net/http.(*conn).serve(0xc000072000, 0x8722c0, 0xc00005e100)
/usr/local/go/src/net/http/server.go:1895 +0x86c
created by net/http.(*Server).Serve
/usr/local/go/src/net/http/server.go:2933 +0x35c
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9 回复
这段代码启动了一个服务器，监听 localhost:8080 上的 HTTP 请求。您具体是向 http://localhost:8080/ 执行了哪个 HTTP 请求，从而导致了错误？
好的，所以你的意思是，在重定向到这个
*时，重定向到这个 URL 时，
foo 函数被执行了
func main() {
fmt.Println("hello world")
}
这是该函数的代码…
func foo(w http.ResponseWriter, req *http.Request) {
var s string
fmt.Println(req.Method)
if req.Method == http.MethodPost {
//打开...
f, h, err := req.FormFile("q")
errorCheck(err, w)
defer f.Close()
fmt.Println("\n文件名: ", f, "\n头部信息:", h, "\n错误:", err)
bs, err := ioutil.ReadAll(f)
errorCheck(err, w)
s = string(bs)
//存储在服务器上...
dst, err := os.Create(filepath.Join("./user/", h.Filename))
errorCheck(err, w)
defer dst.Close()
_, err = dst.Write(bs)
errorCheck(err, w)
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
tpl.ExecuteTemplate(w, "index.gohtml", s)
}
你的代码中存在两个主要问题：
- 模板初始化函数名拼写错误：
inti()应该是init() - 模板执行时未检查错误：
tpl.ExecuteTemplate()可能返回错误
以下是修复后的代码：
package main
import (
"fmt"
"html/template"
"io/ioutil"
"net/http"
"os"
"path/filepath"
)
var tpl *template.Template
func init() {
tpl = template.Must(template.ParseGlob("templates/*"))
}
func main() {
http.HandleFunc("/", foo)
http.Handle("/favicon.ico", http.NotFoundHandler())
http.ListenAndServe(":8080", nil)
}
// check error
func errorCheck(err error, w http.ResponseWriter) {
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
}
//foo call for route “/”
func foo(w http.ResponseWriter, req *http.Request) {
var s string
fmt.Println(req.Method)
if req.Method == http.MethodPost {
//open...
f, h, err := req.FormFile("q")
errorCheck(err, w)
defer f.Close()
fmt.Println("\nfile name: ", f, "\nheader:", h, "\nerror:", err)
bs, err := ioutil.ReadAll(f)
errorCheck(err, w)
s = string(bs)
//store on server...
dst, err := os.Create(filepath.Join("./user/", h.Filename))
errorCheck(err, w)
defer dst.Close()
_, err = dst.Write(bs)
errorCheck(err, w)
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
err := tpl.ExecuteTemplate(w, "index.gohtml", s)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
关键修改：
- 将
inti()改为init()- Go会自动调用这个初始化函数 - 在
tpl.ExecuteTemplate()后添加错误检查
另外，确保你的项目目录结构正确：
project/
├── main.go
└── templates/
└── index.gohtml
index.gohtml 模板文件示例：
<!DOCTYPE html>
<html>
<head>
<title>File Upload</title>
</head>
<body>
<form method="POST" enctype="multipart/form-data">
<input type="file" name="q">
<input type="submit" value="Upload">
</form>
{{if .}}
<h3>File Content:</h3>
<pre>{{.}}</pre>
{{end}}
</body>
</html>
还需要确保 user/ 目录存在，或者在创建文件前检查目录：
// 在创建文件前添加目录检查
err = os.MkdirAll("./user/", 0755)
errorCheck(err, w)
dst, err := os.Create(filepath.Join("./user/", h.Filename))
errorCheck(err, w)
