请教一个模板问题！

为什么parseFiles总是报错 以下为代码 及报错 ```go func login(w http.ResponseWriter,r *http.Request) { fmt.Println("method",r.Method)//看是get还是post if r.Method == "GET" { t,_ := template.ParseFiles("login.html") log.Println(t.Execute(w,nil)) } else { r.ParseForm() fmt.Println("username",r.Form["username"]) fmt.Println("password",r.Form["password"]) } } ``` 错误信息 ``` 2018/03/18 22:32:42 http: panic serving [::1]:51132: runtime error: invalid memory address or nil pointer dereference goroutine 18 [running]: net/http.(*conn).serve.func1(0xc042058dc0) D:/Go/src/net/http/server.go:1726 +0x122 panic(0x8329e0, 0xa5eb50) D:/Go/src/runtime/panic.go:505 +0x258 html/template.(*Template).escape(0x0, 0x0, 0x0) D:/Go/src/html/template/template.go:95 +0x49 html/template.(*Template).Execute(0x0, 0x8ca900, 0xc04215c000, 0x852fe0, 0xc0421381b0, 0x0, 0x0) D:/Go/src/html/template/template.go:119 +0x41 main.login(0x8cd3c0, 0xc04215c000, 0xc042144000) D:/go_workspace/webProject/src/main.go:37 +0x369 net/http.HandlerFunc.ServeHTTP(0x8acd50, 0x8cd3c0, 0xc04215c000, 0xc042144000) D:/Go/src/net/http/server.go:1947 +0x4b net/http.(*ServeMux).ServeHTTP(0xa6d8c0, 0x8cd3c0, 0xc04215c000, 0xc042144000) D:/Go/src/net/http/server.go:2337 +0x1aa net/http.serverHandler.ServeHTTP(0xc042064dd0, 0x8cd3c0, 0xc04215c000, 0xc042144000) D:/Go/src/net/http/server.go:2694 +0x1eb net/http.(*conn).serve(0xc042058dc0, 0x8cd580, 0xc0420160c0) D:/Go/src/net/http/server.go:1830 +0x11f9 created by net/http.(*Server).Serve D:/Go/src/net/http/server.go:2795 +0x6eb 2018/03/18 22:32:42 http: panic serving [::1]:51133: runtime error: invalid memory address or nil pointer dereference goroutine 19 [running]: net/http.(*conn).serve.func1(0xc042058e60) D:/Go/src/net/http/server.go:1726 +0x122 panic(0x8329e0, 0xa5eb50) D:/Go/src/runtime/panic.go:505 +0x258 html/template.(*Template).escape(0x0, 0x0, 0x0) D:/Go/src/html/template/template.go:95 +0x49 html/template.(*Template).Execute(0x0, 0x8ca900, 0xc04215c0e0, 0x852fe0, 0xc0421382a0, 0x0, 0x0) D:/Go/src/html/template/template.go:119 +0x41 main.login(0x8cd3c0, 0xc04215c0e0, 0xc042146000) D:/go_workspace/webProject/src/main.go:37 +0x369 net/http.HandlerFunc.ServeHTTP(0x8acd50, 0x8cd3c0, 0xc04215c0e0, 0xc042146000) D:/Go/src/net/http/server.go:1947 +0x4b net/http.(*ServeMux).ServeHTTP(0xa6d8c0, 0x8cd3c0, 0xc04215c0e0, 0xc042146000) D:/Go/src/net/http/server.go:2337 +0x1aa net/http.serverHandler.ServeHTTP(0xc042064dd0, 0x8cd3c0, 0xc04215c0e0, 0xc042146000) D:/Go/src/net/http/server.go:2694 +0x1eb net/http.(*conn).serve(0xc042058e60, 0x8cd580, 0xc04213a040) D:/Go/src/net/http/server.go:1830 +0x11f9 created by net/http.(*Server).Serve D:/Go/src/net/http/server.go:2795 +0x6eb ```