在此示例中，我们将通过用户界面表单读取-写入-更新JSON文件中的JSON数据，获取特定记录的数据并删除特定记录的数据。
net/http标准库包提供了多种创建HTTP服务器的方法，并附带了一个基本的路由器。此处使用的net/http包用于向服务器发出请求并响应请求。
项目目录结构：
示例代码：main.go
导入net/http包。包http提供HTTP客户端和服务器实现。在main函数中，使用HandleFunc方法创建路由 /。HandleFunc为给定模式注册处理程序函数。HandleFunc阻止我们在执行处理程序之前和之后使用中间件执行任务。ListenAndServe使用给定的地址和处理程序启动HTTP服务器。
package main
import (
handlers "./handlers"
"net/http"
)
func main() {
http.HandleFunc("/addnewuser/", handlers.AddNewUserFunc)
http.HandleFunc("/notsucceded", handlers.NotSucceded)
http.HandleFunc("/deleted", handlers.DeletedFunc)
http.HandleFunc("/deleteuser/deleted", handlers.DeleteUserFunc)
http.HandleFunc("/deleteuser/", handlers.DeleteUserServe)
http.HandleFunc("/deleteuser/notsuccededdelete", handlers.NotSuccededDelete)
http.HandleFunc("/", handlers.IndexFunc)
http.HandleFunc("/showuser/show", handlers.ShowUserFunc)
http.HandleFunc("/showuser/", handlers.ShowUser)
http.HandleFunc("/showuser/notsuccededshow/", handlers.NotSuccededShow)
http.ListenAndServe(":8080", nil)
}
示例代码：list.json
[
{
"id": 1,
"firstName": "Mariya",
"lastName": "Ivanova",
"balance": 300
},
{
"id": 2,
"firstName": "EKatina",
"lastName": "Milevskaya",
"balance": 5000
},
{
"id": 3,
"firstName": "Vasek",
"lastName": "Zalupickiy",
"balance": 2000
}
]
示例代码：handlers\handlers.go
package handlers
import (
model "../model"
"encoding/json"
"fmt"
"html/template"
"io/ioutil"
"net/http"
"os"
"regexp"
"strconv"
)
//function to check correct user adding input (regular expression and non-empty field input)
func checkFormValue(w http.ResponseWriter, r *http.Request, forms ...string) (res bool, errStr string) {
for _, form := range forms {
m, _ := regexp.MatchString("^[a-zA-Z]+$", r.FormValue(form))
if r.FormValue(form) == "" {
return false, "All forms must be completed"
}
if m == false {
return false, "Use only english letters if firstname,lastname forms"
}
}
return true, ""
}
func ShowUser(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "templates/showUser.html")
}
func NotSuccededShow(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "templates/notSuccededShow.html")
}
//handler to show user with id input
func ShowUserFunc(w http.ResponseWriter, r *http.Request) {
if r.Method == "GET" {
t, _ := template.ParseFiles("templates/showUserPage.html")
t.Execute(w, nil)
} else {
id, err := strconv.Atoi(r.FormValue("id"))
checkError(err)
var alUsrs model.AllUsers
file, err := os.OpenFile("list.json", os.O_RDONLY, 0666)
checkError(err)
b, err := ioutil.ReadAll(file)
checkError(err)
json.Unmarshal(b, &alUsrs.Users)
var allID []int
for _, usr := range alUsrs.Users {
allID = append(allID, usr.Id)
}
for _, usr := range alUsrs.Users {
if model.IsValueInSlice(allID, id) != true {
http.Redirect(w, r, "/showuser/notsuccededshow/", 302)
return
}
if usr.Id != id {
continue
} else {
t, err := template.ParseFiles("templates/showUserPage.html")
checkError(err)
t.Execute(w, usr)
}
}
}
}
//function to handle page with successful deletion
func DeletedFunc(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "templates/deleted.html")
}
//serving file with error (add function:empty field input or uncorrect input)
func NotSucceded(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "templates/notSucceded.html")
}
//function,which serve html file,when deleting was not succesful(id input is not correct)
func NotSuccededDelete(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "templates/notSuccededDelete.html")
}
//function,which serve page with delete information input
func DeleteUserServe(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "templates/deleteUser.html")
}
//function to delete user
func DeleteUserFunc(w http.ResponseWriter, r *http.Request) {
if r.Method == "GET" {
t, _ := template.ParseFiles("templates/deleteUser.html")
t.Execute(w, nil)
} else {
r.ParseForm()
id, err := strconv.Atoi(r.FormValue("id"))
checkError(err)
//open file with users
file, err := os.OpenFile("list.json", os.O_RDWR|os.O_APPEND, 0666)
defer file.Close()
//read file and unmarshall json to []users
b, err := ioutil.ReadAll(file)
var alUsrs model.AllUsers
err = json.Unmarshal(b, &alUsrs.Users)
checkError(err)
var allID []int
for _, usr := range alUsrs.Users {
allID = append(allID, usr.Id)
}
for i, usr := range alUsrs.Users {
if model.IsValueInSlice(allID, id) != true {
http.Redirect(w, r, "/deleteuser/notsuccededdelete", 302)
return
}
if usr.Id != id {
continue
} else {
alUsrs.Users = append(alUsrs.Users[:i], alUsrs.Users[i+1:]...)
}
}
newUserBytes, err := json.MarshalIndent(&alUsrs.Users, "", " ")
checkError(err)
ioutil.WriteFile("list.json", newUserBytes, 0666)
http.Redirect(w, r, "/deleted", 301)
}
}
func checkError(err error) {
if err != nil {
fmt.Println(err)
}
}
//function to add user
func AddNewUserFunc(w http.ResponseWriter, r *http.Request) {
//creating new instance and checking method
newUser := &model.User{}
if r.Method == "GET" {
t, _ := template.ParseFiles("templates/addNewUser.html")
t.Execute(w, nil)
} else {
resBool, errStr := checkFormValue(w, r, "firstname", "lastname")
if resBool == false {
t, err := template.ParseFiles("templates/notSucceded.html")
checkError(err)
t.Execute(w, errStr)
return
}
newUser.FirstName = r.FormValue("firstname")
newUser.LastName = r.FormValue("lastname")
var err error
newUser.Balance, err = strconv.ParseFloat(r.FormValue("balance"), 64)
checkError(err)
//open file
file, err := os.OpenFile("list.json", os.O_RDWR, 0644)
checkError(err)
defer file.Close()
//read file and unmarshall json file to slice of users
b, err := ioutil.ReadAll(file)
var alUsrs model.AllUsers
err = json.Unmarshal(b, &alUsrs.Users)
checkError(err)
max := 0
//generation of id(last id at the json file+1)
for _, usr := range alUsrs.Users {
if usr.Id > max {
max = usr.Id
}
}
id := max + 1
newUser.Id = id
//appending newUser to slice of all Users and rewrite json file
alUsrs.Users = append(alUsrs.Users, newUser)
newUserBytes, err := json.MarshalIndent(&alUsrs.Users, "", " ")
checkError(err)
ioutil.WriteFile("list.json", newUserBytes, 0666)
http.Redirect(w, r, "/", 301)
}
}
//Index page handler
func IndexFunc(w http.ResponseWriter, r *http.Request) {
au := model.ShowAllUsers()
t, err := template.ParseFiles("templates/indexPage.html")
checkError(err)
t.Execute(w, au)
}
示例代码：model/model.go
package model
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
)
func checkError(err error) {
if err != nil {
fmt.Println(err)
}
}
func IsValueInSlice(slice []int, value int) (result bool) {
for _, n := range slice {
if n == value {
return true
}
}
return false
}
type User struct {
Id int `json:"id"`
FirstName string `json:"firstName"`
LastName string `json:"lastName"`
Balance float64 `json:"balance"`
}
type AllUsers struct {
Users []*User
}
func ShowAllUsers() (au *AllUsers) {
file, err := os.OpenFile("list.json", os.O_RDWR|os.O_APPEND, 0666)
checkError(err)
b, err := ioutil.ReadAll(file)
var alUsrs AllUsers
json.Unmarshal(b, &alUsrs.Users)
checkError(err)
return &alUsrs
}
示例代码：templates\indexPage.html
<html>
<head>
<title>User info</title>
</head>
<body>
{{range .Users}}
<div><h3> ID:{{ .Id }} </h3></div>
<div> First Name:{{ .FirstName }}</div>
<div> Last Name:{{ .LastName }} </div>
<div> Balance:{{ .Balance }}</div>
{{end}}
<h1>Options</h1>
<form action="/addnewuser/">
<button type="submit">Add new user</button>
</form>
<form action="/deleteuser/">
<button type="submit">Delete user</button>
</form>
<form action="/showuser/">
<button type="submit">Show user</button>
</form>
</body>
</html>
示例代码：templates\addNewUser.html
<html>
<head>
<title>Adding new user</title>
</head>
<body>
<h2>New user's data</h2>
<form method="POST" action="useraded">
<label>Enter firstname</label><br>
<input type="text" name="firstname" /><br><br>
<label>Enter lastname</label><br>
<input type="text" name="lastname" /><br><br>
<label>Enter balance</label><br>
<input type="number" name="balance" /><br><br>
<input type="submit" value="Submit" />
</form>
</body>
</html>
示例代码：templates\deleteUser.html
<html>
<head>
<title>Delete user</title>
</head>
<body>
<h2>Please,write an id of user you want to delete</h2>
<form method="POST" action="deleted">
<label>Enter id</label><br>
<input type="text" name="id" /><br><br>
<input type="submit" value="Submit" />
</form>
</body>
</html>
示例代码：templates\deleted.html
<html>
<head>
<title>User info</title>
</head>
<body>
<div>Done</div><br><br>
<form action="/">
<button type="submit">Back to main</button>
</form>
</body>
</html>
示例代码：templates\notSuccededDelete.html
<html>
<head>
<title>User info</title>
</head>
<body>
<div>There is no user with such ID</div><br><br>
<form action="/">
<button type="submit">Back to main</button>
</form>
</body>
</html>
示例代码：templates\notSuccededShow.html
<html>
<head>
<title>User info</title>
</head>
<body>
<div>Error:Cant find User with such ID,try again</div><br><br>
<form action="/">
<button type="submit">Back to main</button>
</form>
</body>
</html>
示例代码：templates\showUser.html
<html>
<head>
<title>Show user</title>
</head>
<body>
<h2>Please,write an id of user you want to show</h2>
<form method="POST" action="show">
<label>Enter id</label><br>
<input type="text" name="id" /><br><br>
<input type="submit" value="Submit" />
</form>
</body>
</html>
示例代码：templates\showUserPage.html
<html>
<head>
<title>User info</title>
</head>
<body>
<div><h3> ID:{{.Id}} </h3></div>
<div> First Name:{{ .FirstName }}</div>
<div> Last Name:{{ .LastName }} </div>
<div> Balance:{{ .Balance }}</div>
</body>
</html>
示例代码：templates\notSucceded.html
<html>
<head>
<title>User info</title>
</head>
<body>
<div>Error:{{.}}</div><br><br>
<form action="/">
<button type="submit">Back to main</button>
</form>
</body>
</html>
运行应用程序：
go run main.go
在浏览器访问http://localhost:8080即可看到如下页面
