golang 官方代码汇总

go1.22.2

序章

golang 官网的代码汇总，汇总到一起，方便查阅。

注，如有侵权，请通知我处理🥂。

go.dev 首页

说明，go.dev 访问时，可能存在访问失败的情况。

搜索：Try Go

package main

import "fmt"

func main() {
	fmt.Println("Hello, 世界")
}

// An implementation of Conway's Game of Life.
package main

import (
	"bytes"
	"fmt"
	"math/rand"
	"time"
)

// Field represents a two-dimensional field of cells.
type Field struct {
	s    [][]bool
	w, h int
}

// NewField returns an empty field of the specified width and height.
func NewField(w, h int) *Field {
	s := make([][]bool, h)
	for i := range s {
		s[i] = make([]bool, w)
	}
	return &Field{s: s, w: w, h: h}
}

// Set sets the state of the specified cell to the given value.
func (f *Field) Set(x, y int, b bool) {
	f.s[y][x] = b
}

// Alive reports whether the specified cell is alive.
// If the x or y coordinates are outside the field boundaries they are wrapped
// toroidally. For instance, an x value of -1 is treated as width-1.
func (f *Field) Alive(x, y int) bool {
	x += f.w
	x %= f.w
	y += f.h
	y %= f.h
	return f.s[y][x]
}

// Next returns the state of the specified cell at the next time step.
func (f *Field) Next(x, y int) bool {
	// Count the adjacent cells that are alive.
	alive := 0
	for i := -1; i <= 1; i++ {
		for j := -1; j <= 1; j++ {
			if (j != 0 || i != 0) && f.Alive(x+i, y+j) {
				alive++
			}
		}
	}
	// Return next state according to the game rules:
	//   exactly 3 neighbors: on,
	//   exactly 2 neighbors: maintain current state,
	//   otherwise: off.
	return alive == 3 || alive == 2 && f.Alive(x, y)
}

// Life stores the state of a round of Conway's Game of Life.
type Life struct {
	a, b *Field
	w, h int
}

// NewLife returns a new Life game state with a random initial state.
func NewLife(w, h int) *Life {
	a := NewField(w, h)
	for i := 0; i < (w * h / 4); i++ {
		a.Set(rand.Intn(w), rand.Intn(h), true)
	}
	return &Life{
		a: a, b: NewField(w, h),
		w: w, h: h,
	}
}

// Step advances the game by one instant, recomputing and updating all cells.
func (l *Life) Step() {
	// Update the state of the next field (b) from the current field (a).
	for y := 0; y < l.h; y++ {
		for x := 0; x < l.w; x++ {
			l.b.Set(x, y, l.a.Next(x, y))
		}
	}
	// Swap fields a and b.
	l.a, l.b = l.b, l.a
}

// String returns the game board as a string.
func (l *Life) String() string {
	var buf bytes.Buffer
	for y := 0; y < l.h; y++ {
		for x := 0; x < l.w; x++ {
			b := byte(' ')
			if l.a.Alive(x, y) {
				b = '*'
			}
			buf.WriteByte(b)
		}
		buf.WriteByte('\n')
	}
	return buf.String()
}

func main() {
	l := NewLife(40, 15)
	for i := 0; i < 300; i++ {
		l.Step()
		fmt.Print("\x0c", l) // Clear screen and print field.
		time.Sleep(time.Second / 30)
	}
}

package main

import "fmt"

// fib returns a function that returns
// successive Fibonacci numbers.
func fib() func() int {
	a, b := 0, 1
	return func() int {
		a, b = b, a+b
		return a
	}
}

func main() {
	f := fib()
	// Function calls are evaluated left-to-right.
	fmt.Println(f(), f(), f(), f(), f())
}

// This program demonstrates that Go's automatic
// stack management can handle heavily recursive
// computations.

package main

import "fmt"

// Number is a pointer to a Number
type Number *Number

// The arithmetic value of a Number is the
// count of the nodes comprising the list.
// (See the count function below.)

// -------------------------------------
// Peano primitives

func zero() *Number {
	return nil
}

func isZero(x *Number) bool {
	return x == nil
}

func add1(x *Number) *Number {
	e := new(Number)
	*e = x
	return e
}

func sub1(x *Number) *Number {
	return *x
}

func add(x, y *Number) *Number {
	if isZero(y) {
		return x
	}
	return add(add1(x), sub1(y))
}

func mul(x, y *Number) *Number {
	if isZero(x) || isZero(y) {
		return zero()
	}
	return add(mul(x, sub1(y)), x)
}

func fact(n *Number) *Number {
	if isZero(n) {
		return add1(zero())
	}
	return mul(fact(sub1(n)), n)
}

// -------------------------------------
// Helpers to generate/count Peano integers

func gen(n int) *Number {
	if n > 0 {
		return add1(gen(n - 1))
	}
	return zero()
}

func count(x *Number) int {
	if isZero(x) {
		return 0
	}
	return count(sub1(x)) + 1
}

// -------------------------------------
// Print i! for i in [0,9]

func main() {
	for i := 0; i <= 9; i++ {
		f := count(fact(gen(i)))
		fmt.Println(i, "! =", f)
	}
}

// Concurrent computation of pi.
// The implementation uses the Nilakantha Series.
//
// This demonstrates Go's ability to handle
// large numbers of concurrent processes.
// It is an unreasonable way to calculate pi.
package main

import (
	"fmt"
	"math"
)

func main() {
	fmt.Println("          math.Pi:", math.Pi)
	fmt.Println("Nilakantha Series:", pi(5000))
}

// pi launches n goroutines to compute an
// approximation of pi.
func pi(n int) float64 {
	ch := make(chan float64)
	for k := 0; k < n; k++ {
		go term(ch, float64(k))
	}
	f := 3.0
	for k := 0; k < n; k++ {
		f += <-ch
	}
	return f
}

func term(ch chan float64, k float64) {
	ch <- 4 * math.Pow(-1, k) / ((2*k + 2) * (2*k + 3) * (2*k + 4))
}

// A concurrent prime sieve

package main

import "fmt"

// Send the sequence 2, 3, 4, ... to channel 'ch'.
func Generate(ch chan<- int) {
	for i := 2; ; i++ {
		ch <- i // Send 'i' to channel 'ch'.
	}
}

// Copy the values from channel 'in' to channel 'out',
// removing those divisible by 'prime'.
func Filter(in <-chan int, out chan<- int, prime int) {
	for {
		i := <-in // Receive value from 'in'.
		if i%prime != 0 {
			out <- i // Send 'i' to 'out'.
		}
	}
}

// The prime sieve: Daisy-chain Filter processes.
func main() {
	ch := make(chan int) // Create a new channel.
	go Generate(ch)      // Launch Generate goroutine.
	for i := 0; i < 10; i++ {
		prime := <-ch
		fmt.Println(prime)
		ch1 := make(chan int)
		go Filter(ch, ch1, prime)
		ch = ch1
	}
}

// This program solves the (English) peg
// solitaire board game.
// http://en.wikipedia.org/wiki/Peg_solitaire

package main

import "fmt"

const N = 11 + 1 // length of a row (+1 for \n)

// The board must be surrounded by 2 illegal
// fields in each direction so that move()
// doesn't need to check the board boundaries.
// Periods represent illegal fields,
// ● are pegs, and ○ are holes.

var board = []rune(
	`...........
...........
....●●●....
....●●●....
..●●●●●●●..
..●●●○●●●..
..●●●●●●●..
....●●●....
....●●●....
...........
...........
`)

// center is the position of the center hole if
// there is a single one; otherwise it is -1.
var center int

func init() {
	n := 0
	for pos, field := range board {
		if field == '○' {
			center = pos
			n++
		}
	}
	if n != 1 {
		center = -1 // no single hole
	}
}

var moves int // number of times move is called

// move tests if there is a peg at position pos that
// can jump over another peg in direction dir. If the
// move is valid, it is executed and move returns true.
// Otherwise, move returns false.
func move(pos, dir int) bool {
	moves++
	if board[pos] == '●' && board[pos+dir] == '●' && board[pos+2*dir] == '○' {
		board[pos] = '○'
		board[pos+dir] = '○'
		board[pos+2*dir] = '●'
		return true
	}
	return false
}

// unmove reverts a previously executed valid move.
func unmove(pos, dir int) {
	board[pos] = '●'
	board[pos+dir] = '●'
	board[pos+2*dir] = '○'
}

// solve tries to find a sequence of moves such that
// there is only one peg left at the end; if center is
// >= 0, that last peg must be in the center position.
// If a solution is found, solve prints the board after
// each move in a backward fashion (i.e., the last
// board position is printed first, all the way back to
// the starting board position).
func solve() bool {
	var last, n int
	for pos, field := range board {
		// try each board position
		if field == '●' {
			// found a peg
			for _, dir := range [...]int{-1, -N, +1, +N} {
				// try each direction
				if move(pos, dir) {
					// a valid move was found and executed,
					// see if this new board has a solution
					if solve() {
						unmove(pos, dir)
						fmt.Println(string(board))
						return true
					}
					unmove(pos, dir)
				}
			}
			last = pos
			n++
		}
	}
	// tried each possible move
	if n == 1 && (center < 0 || last == center) {
		// there's only one peg left
		fmt.Println(string(board))
		return true
	}
	// no solution found for this board
	return false
}

func main() {
	if !solve() {
		fmt.Println("no solution found")
	}
	fmt.Println(moves, "moves tried")
}

// Go's concurrency primitives make it easy to
// express concurrent concepts, such as
// this binary tree comparison.
//
// Trees may be of different shapes,
// but have the same contents. For example:
//
//        4               6
//      2   6          4     7
//     1 3 5 7       2   5
//                  1 3
//
// This program compares a pair of trees by
// walking each in its own goroutine,
// sending their contents through a channel
// to a third goroutine that compares them.

package main

import (
	"fmt"
	"math/rand"
)

// A Tree is a binary tree with integer values.
type Tree struct {
	Left  *Tree
	Value int
	Right *Tree
}

// Walk traverses a tree depth-first,
// sending each Value on a channel.
func Walk(t *Tree, ch chan int) {
	if t == nil {
		return
	}
	Walk(t.Left, ch)
	ch <- t.Value
	Walk(t.Right, ch)
}

// Walker launches Walk in a new goroutine,
// and returns a read-only channel of values.
func Walker(t *Tree) <-chan int {
	ch := make(chan int)
	go func() {
		Walk(t, ch)
		close(ch)
	}()
	return ch
}

// Compare reads values from two Walkers
// that run simultaneously, and returns true
// if t1 and t2 have the same contents.
func Compare(t1, t2 *Tree) bool {
	c1, c2 := Walker(t1), Walker(t2)
	for {
		v1, ok1 := <-c1
		v2, ok2 := <-c2
		if !ok1 || !ok2 {
			return ok1 == ok2
		}
		if v1 != v2 {
			break
		}
	}
	return false
}

// New returns a new, random binary tree
// holding the values 1k, 2k, ..., nk.
func New(n, k int) *Tree {
	var t *Tree
	for _, v := range rand.Perm(n) {
		t = insert(t, (1+v)*k)
	}
	return t
}

func insert(t *Tree, v int) *Tree {
	if t == nil {
		return &Tree{nil, v, nil}
	}
	if v < t.Value {
		t.Left = insert(t.Left, v)
		return t
	}
	t.Right = insert(t.Right, v)
	return t
}

func main() {
	t1 := New(100, 1)
	fmt.Println(Compare(t1, New(100, 1)), "Same Contents")
	fmt.Println(Compare(t1, New(99, 1)), "Differing Sizes")
	fmt.Println(Compare(t1, New(100, 2)), "Differing Values")
	fmt.Println(Compare(t1, New(101, 2)), "Dissimilar")
}

Go Tutorials

https://golang.google.cn/doc/tutorial/

注，其中【Create a module】下有多个页面。

Getting started

package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}

package main

import "fmt"

import "rsc.io/quote"

func main() {
    fmt.Println(quote.Go())
}

Create a module

package greetings

import "fmt"

// Hello returns a greeting for the named person.
func Hello(name string) string {
    // Return a greeting that embeds the name in a message.
    message := fmt.Sprintf("Hi, %v. Welcome!", name)
    return message
}

package main

import (
    "fmt"

    "example.com/greetings"
)

func main() {
    // Get a greeting message and print it.
    message := greetings.Hello("Gladys")
    fmt.Println(message)
}

package greetings

import (
    "errors"
    "fmt"
)

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
    // If no name was given, return an error with a message.
    if name == "" {
        return "", errors.New("empty name")
    }

    // If a name was received, return a value that embeds the name
    // in a greeting message.
    message := fmt.Sprintf("Hi, %v. Welcome!", name)
    return message, nil
}

package main

import (
    "fmt"
    "log"

    "example.com/greetings"
)

func main() {
    // Set properties of the predefined Logger, including
    // the log entry prefix and a flag to disable printing
    // the time, source file, and line number.
    log.SetPrefix("greetings: ")
    log.SetFlags(0)

    // Request a greeting message.
    message, err := greetings.Hello("")
    // If an error was returned, print it to the console and
    // exit the program.
    if err != nil {
        log.Fatal(err)
    }

    // If no error was returned, print the returned message
    // to the console.
    fmt.Println(message)
}

package greetings

import (
    "errors"
    "fmt"
    "math/rand"
)

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
    // If no name was given, return an error with a message.
    if name == "" {
        return name, errors.New("empty name")
    }
    // Create a message using a random format.
    message := fmt.Sprintf(randomFormat(), name)
    return message, nil
}

// randomFormat returns one of a set of greeting messages. The returned
// message is selected at random.
func randomFormat() string {
    // A slice of message formats.
    formats := []string{
        "Hi, %v. Welcome!",
        "Great to see you, %v!",
        "Hail, %v! Well met!",
    }

    // Return a randomly selected message format by specifying
    // a random index for the slice of formats.
    return formats[rand.Intn(len(formats))]
}

package main

import (
    "fmt"
    "log"

    "example.com/greetings"
)

func main() {
    // Set properties of the predefined Logger, including
    // the log entry prefix and a flag to disable printing
    // the time, source file, and line number.
    log.SetPrefix("greetings: ")
    log.SetFlags(0)

    // Request a greeting message.
    message, err := greetings.Hello("Gladys")
    // If an error was returned, print it to the console and
    // exit the program.
    if err != nil {
        log.Fatal(err)
    }

    // If no error was returned, print the returned message
    // to the console.
    fmt.Println(message)
}

package greetings

import (
    "errors"
    "fmt"
    "math/rand"
)

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
    // If no name was given, return an error with a message.
    if name == "" {
        return name, errors.New("empty name")
    }
    // Create a message using a random format.
    message := fmt.Sprintf(randomFormat(), name)
    return message, nil
}

// Hellos returns a map that associates each of the named people
// with a greeting message.
func Hellos(names []string) (map[string]string, error) {
    // A map to associate names with messages.
    messages := make(map[string]string)
    // Loop through the received slice of names, calling
    // the Hello function to get a message for each name.
    for _, name := range names {
        message, err := Hello(name)
        if err != nil {
            return nil, err
        }
        // In the map, associate the retrieved message with
        // the name.
        messages[name] = message
    }
    return messages, nil
}

// randomFormat returns one of a set of greeting messages. The returned
// message is selected at random.
func randomFormat() string {
    // A slice of message formats.
    formats := []string{
        "Hi, %v. Welcome!",
        "Great to see you, %v!",
        "Hail, %v! Well met!",
    }

    // Return one of the message formats selected at random.
    return formats[rand.Intn(len(formats))]
}

package main

import (
    "fmt"
    "log"

    "example.com/greetings"
)

func main() {
    // Set properties of the predefined Logger, including
    // the log entry prefix and a flag to disable printing
    // the time, source file, and line number.
    log.SetPrefix("greetings: ")
    log.SetFlags(0)

    // A slice of names.
    names := []string{"Gladys", "Samantha", "Darrin"}

    // Request greeting messages for the names.
    messages, err := greetings.Hellos(names)
    if err != nil {
        log.Fatal(err)
    }
    // If no error was returned, print the returned map of
    // messages to the console.
    fmt.Println(messages)
}

Add a test

package greetings

import (
    "testing"
    "regexp"
)

// TestHelloName calls greetings.Hello with a name, checking
// for a valid return value.
func TestHelloName(t *testing.T) {
    name := "Gladys"
    want := regexp.MustCompile(`\b`+name+`\b`)
    msg, err := Hello("Gladys")
    if !want.MatchString(msg) || err != nil {
        t.Fatalf(`Hello("Gladys") = %q, %v, want match for %#q, nil`, msg, err, want)
    }
}

// TestHelloEmpty calls greetings.Hello with an empty string,
// checking for an error.
func TestHelloEmpty(t *testing.T) {
    msg, err := Hello("")
    if msg != "" || err == nil {
        t.Fatalf(`Hello("") = %q, %v, want "", error`, msg, err)
    }
}

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
    // If no name was given, return an error with a message.
    if name == "" {
        return name, errors.New("empty name")
    }
    // Create a message using a random format.
    // message := fmt.Sprintf(randomFormat(), name)
    message := fmt.Sprint(randomFormat())
    return message, nil
}

Getting started with multi-module workspaces

package main

import (
    "fmt"

    "golang.org/x/example/hello/reverse"
)

func main() {
    fmt.Println(reverse.String("Hello"))
}

package reverse

import "strconv"

// Int returns the decimal reversal of the integer i.
func Int(i int) int {
    i, _ = strconv.Atoi(String(strconv.Itoa(i)))
    return i
}

package main

import (
    "fmt"

    "golang.org/x/example/hello/reverse"
)

func main() {
    fmt.Println(reverse.String("Hello"), reverse.Int(24601))
}

Accessing a relational database

# mysql

var db *sql.DB

func main() {
    // Capture connection properties.
    cfg := mysql.Config{
        User:   os.Getenv("DBUSER"),
        Passwd: os.Getenv("DBPASS"),
        Net:    "tcp",
        Addr:   "127.0.0.1:3306",
        DBName: "recordings",
    }
    // Get a database handle.
    var err error
    db, err = sql.Open("mysql", cfg.FormatDSN())
    if err != nil {
        log.Fatal(err)
    }

    pingErr := db.Ping()
    if pingErr != nil {
        log.Fatal(pingErr)
    }
    fmt.Println("Connected!")
}

package main

import (
    "database/sql"
    "fmt"
    "log"
    "os"

    "github.com/go-sql-driver/mysql"
)

完整代码 Completed code

package main

import (
    "database/sql"
    "fmt"
    "log"
    "os"

    "github.com/go-sql-driver/mysql"
)

var db *sql.DB

type Album struct {
    ID     int64
    Title  string
    Artist string
    Price  float32
}

func main() {
    // Capture connection properties.
    cfg := mysql.Config{
        User:   os.Getenv("DBUSER"),
        Passwd: os.Getenv("DBPASS"),
        Net:    "tcp",
        Addr:   "127.0.0.1:3306",
        DBName: "recordings",
    }
    // Get a database handle.
    var err error
    db, err = sql.Open("mysql", cfg.FormatDSN())
    if err != nil {
        log.Fatal(err)
    }

    pingErr := db.Ping()
    if pingErr != nil {
        log.Fatal(pingErr)
    }
    fmt.Println("Connected!")

    albums, err := albumsByArtist("John Coltrane")
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("Albums found: %v\n", albums)

    // Hard-code ID 2 here to test the query.
    alb, err := albumByID(2)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("Album found: %v\n", alb)

    albID, err := addAlbum(Album{
        Title:  "The Modern Sound of Betty Carter",
        Artist: "Betty Carter",
        Price:  49.99,
    })
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("ID of added album: %v\n", albID)
}

// albumsByArtist queries for albums that have the specified artist name.
func albumsByArtist(name string) ([]Album, error) {
    // An albums slice to hold data from returned rows.
    var albums []Album

    rows, err := db.Query("SELECT * FROM album WHERE artist = ?", name)
    if err != nil {
        return nil, fmt.Errorf("albumsByArtist %q: %v", name, err)
    }
    defer rows.Close()
    // Loop through rows, using Scan to assign column data to struct fields.
    for rows.Next() {
        var alb Album
        if err := rows.Scan(&alb.ID, &alb.Title, &alb.Artist, &alb.Price); err != nil {
            return nil, fmt.Errorf("albumsByArtist %q: %v", name, err)
        }
        albums = append(albums, alb)
    }
    if err := rows.Err(); err != nil {
        return nil, fmt.Errorf("albumsByArtist %q: %v", name, err)
    }
    return albums, nil
}

// albumByID queries for the album with the specified ID.
func albumByID(id int64) (Album, error) {
    // An album to hold data from the returned row.
    var alb Album

    row := db.QueryRow("SELECT * FROM album WHERE id = ?", id)
    if err := row.Scan(&alb.ID, &alb.Title, &alb.Artist, &alb.Price); err != nil {
        if err == sql.ErrNoRows {
            return alb, fmt.Errorf("albumsById %d: no such album", id)
        }
        return alb, fmt.Errorf("albumsById %d: %v", id, err)
    }
    return alb, nil
}

// addAlbum adds the specified album to the database,
// returning the album ID of the new entry
func addAlbum(alb Album) (int64, error) {
    result, err := db.Exec("INSERT INTO album (title, artist, price) VALUES (?, ?, ?)", alb.Title, alb.Artist, alb.Price)
    if err != nil {
        return 0, fmt.Errorf("addAlbum: %v", err)
    }
    id, err := result.LastInsertId()
    if err != nil {
        return 0, fmt.Errorf("addAlbum: %v", err)
    }
    return id, nil
}

Developing a RESTful API with Go and Gin

完整代码 Completed code

package main

import (
    "net/http"

    "github.com/gin-gonic/gin"
)

// album represents data about a record album.
type album struct {
    ID     string  `json:"id"`
    Title  string  `json:"title"`
    Artist string  `json:"artist"`
    Price  float64 `json:"price"`
}

// albums slice to seed record album data.
var albums = []album{
    {ID: "1", Title: "Blue Train", Artist: "John Coltrane", Price: 56.99},
    {ID: "2", Title: "Jeru", Artist: "Gerry Mulligan", Price: 17.99},
    {ID: "3", Title: "Sarah Vaughan and Clifford Brown", Artist: "Sarah Vaughan", Price: 39.99},
}

func main() {
    router := gin.Default()
    router.GET("/albums", getAlbums)
    router.GET("/albums/:id", getAlbumByID)
    router.POST("/albums", postAlbums)

    router.Run("localhost:8080")
}

// getAlbums responds with the list of all albums as JSON.
func getAlbums(c *gin.Context) {
    c.IndentedJSON(http.StatusOK, albums)
}

// postAlbums adds an album from JSON received in the request body.
func postAlbums(c *gin.Context) {
    var newAlbum album

    // Call BindJSON to bind the received JSON to
    // newAlbum.
    if err := c.BindJSON(&newAlbum); err != nil {
        return
    }

    // Add the new album to the slice.
    albums = append(albums, newAlbum)
    c.IndentedJSON(http.StatusCreated, newAlbum)
}

// getAlbumByID locates the album whose ID value matches the id
// parameter sent by the client, then returns that album as a response.
func getAlbumByID(c *gin.Context) {
    id := c.Param("id")

    // Loop through the list of albums, looking for
    // an album whose ID value matches the parameter.
    for _, a := range albums {
        if a.ID == id {
            c.IndentedJSON(http.StatusOK, a)
            return
        }
    }
    c.IndentedJSON(http.StatusNotFound, gin.H{"message": "album not found"})
}

Getting started with generics

# 泛型

完整代码 Completed code

package main

import "fmt"

type Number interface {
    int64 | float64
}

func main() {
    // Initialize a map for the integer values
    ints := map[string]int64{
        "first": 34,
        "second": 12,
    }

    // Initialize a map for the float values
    floats := map[string]float64{
        "first": 35.98,
        "second": 26.99,
    }

    fmt.Printf("Non-Generic Sums: %v and %v\n",
        SumInts(ints),
        SumFloats(floats))

    fmt.Printf("Generic Sums: %v and %v\n",
        SumIntsOrFloats[string, int64](ints),
        SumIntsOrFloats[string, float64](floats))

    fmt.Printf("Generic Sums, type parameters inferred: %v and %v\n",
        SumIntsOrFloats(ints),
        SumIntsOrFloats(floats))

    fmt.Printf("Generic Sums with Constraint: %v and %v\n",
        SumNumbers(ints),
        SumNumbers(floats))
}

// SumInts adds together the values of m.
func SumInts(m map[string]int64) int64 {
    var s int64
    for _, v := range m {
        s += v
    }
    return s
}

// SumFloats adds together the values of m.
func SumFloats(m map[string]float64) float64 {
    var s float64
    for _, v := range m {
        s += v
    }
    return s
}

// SumIntsOrFloats sums the values of map m. It supports both floats and integers
// as map values.
func SumIntsOrFloats[K comparable, V int64 | float64](m map[K]V) V {
    var s V
    for _, v := range m {
        s += v
    }
    return s
}

// SumNumbers sums the values of map m. Its supports both integers
// and floats as map values.
func SumNumbers[K comparable, V Number](m map[K]V) V {
    var s V
    for _, v := range m {
        s += v
    }
    return s
}

Getting started with fuzzing

完整代码 Completed code

// main.go
package main

import (
    "errors"
    "fmt"
    "unicode/utf8"
)

func main() {
    input := "The quick brown fox jumped over the lazy dog"
    rev, revErr := Reverse(input)
    doubleRev, doubleRevErr := Reverse(rev)
    fmt.Printf("original: %q\n", input)
    fmt.Printf("reversed: %q, err: %v\n", rev, revErr)
    fmt.Printf("reversed again: %q, err: %v\n", doubleRev, doubleRevErr)
}

func Reverse(s string) (string, error) {
    if !utf8.ValidString(s) {
        return s, errors.New("input is not valid UTF-8")
    }
    r := []rune(s)
    for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
        r[i], r[j] = r[j], r[i]
    }
    return string(r), nil
}

// reverse_test.go
package main

import (
    "testing"
    "unicode/utf8"
)

func FuzzReverse(f *testing.F) {
    testcases := []string{"Hello, world", " ", "!12345"}
    for _, tc := range testcases {
        f.Add(tc) // Use f.Add to provide a seed corpus
    }
    f.Fuzz(func(t *testing.T, orig string) {
        rev, err1 := Reverse(orig)
        if err1 != nil {
            return
        }
        doubleRev, err2 := Reverse(rev)
        if err2 != nil {
            return
        }
        if orig != doubleRev {
            t.Errorf("Before: %q, after: %q", orig, doubleRev)
        }
        if utf8.ValidString(orig) && !utf8.ValidString(rev) {
            t.Errorf("Reverse produced invalid UTF-8 string %q", rev)
        }
    })
}

Getting started with govulncheck

漏洞检测和修复

命令

$ mkdir vuln-tutorial
$ cd vuln-tutorial
$ go mod init vuln.tutorial

$ go install golang.org/x/vuln/cmd/govulncheck@latest

$ govulncheck ./...

测试代码：

// main.go
package main

import (
        "fmt"
        "os"

        "golang.org/x/text/language"
)

func main() {
        for _, arg := range os.Args[1:] {
                tag, err := language.Parse(arg)
                if err != nil {
                        fmt.Printf("%s: error: %v\n", arg, err)
                } else if tag == language.Und {
                        fmt.Printf("%s: undefined\n", arg)
                } else {
                        fmt.Printf("%s: tag %s\n", arg, tag)
                }
        }
}

Find and fix vulnerable dependencies with VS Code Go

测试代码同上

Go Web Examples

https://gowebexamples.com

Web 开发相关示例。

Hello World

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprintf(w, "Hello, you've requested: %s\n", r.URL.Path)
    })

    http.ListenAndServe(":80", nil)
}

HTTP Server

https://gowebexamples.com/http-server/

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", func (w http.ResponseWriter, r *http.Request) {
        fmt.Fprintf(w, "Welcome to my website!")
    })

    fs := http.FileServer(http.Dir("static/"))
    http.Handle("/static/", http.StripPrefix("/static/", fs))

    http.ListenAndServe(":80", nil)
}

Routing (using gorilla/mux)

https://gowebexamples.com/routes-using-gorilla-mux/

go get -u github.com/gorilla/mux

package main

import (
    "fmt"
    "net/http"

    "github.com/gorilla/mux"
)

func main() {
    r := mux.NewRouter()

    r.HandleFunc("/books/{title}/page/{page}", func(w http.ResponseWriter, r *http.Request) {
        vars := mux.Vars(r)
        title := vars["title"]
        page := vars["page"]

        fmt.Fprintf(w, "You've requested the book: %s on page %s\n", title, page)
    })

    http.ListenAndServe(":80", r)
}

// Restrict the request handler to specific HTTP methods.
r.HandleFunc("/books/{title}", CreateBook).Methods("POST")
r.HandleFunc("/books/{title}", ReadBook).Methods("GET")
r.HandleFunc("/books/{title}", UpdateBook).Methods("PUT")
r.HandleFunc("/books/{title}", DeleteBook).Methods("DELETE")

// Restrict the request handler to specific hostnames or subdomains.
r.HandleFunc("/books/{title}", BookHandler).Host("www.mybookstore.com")

// Restrict the request handler to http/https.
r.HandleFunc("/secure", SecureHandler).Schemes("https")
r.HandleFunc("/insecure", InsecureHandler).Schemes("http")

// Restrict the request handler to specific path prefixes.
bookrouter := r.PathPrefix("/books").Subrouter()
bookrouter.HandleFunc("/", AllBooks)
bookrouter.HandleFunc("/{title}", GetBook)

MySQL Database

https://gowebexamples.com/mysql-database/

go get -u github.com/go-sql-driver/mysql

package main

import (
    "database/sql"
    "fmt"
    "log"
    "time"

    _ "github.com/go-sql-driver/mysql"
)

func main() {
    db, err := sql.Open("mysql", "root:root@(127.0.0.1:3306)/root?parseTime=true")
    if err != nil {
        log.Fatal(err)
    }
    if err := db.Ping(); err != nil {
        log.Fatal(err)
    }

    { // Create a new table
        query := `
            CREATE TABLE users (
                id INT AUTO_INCREMENT,
                username TEXT NOT NULL,
                password TEXT NOT NULL,
                created_at DATETIME,
                PRIMARY KEY (id)
            );`

        if _, err := db.Exec(query); err != nil {
            log.Fatal(err)
        }
    }

    { // Insert a new user
        username := "johndoe"
        password := "secret"
        createdAt := time.Now()

        result, err := db.Exec(`INSERT INTO users (username, password, created_at) VALUES (?, ?, ?)`, username, password, createdAt)
        if err != nil {
            log.Fatal(err)
        }

        id, err := result.LastInsertId()
        fmt.Println(id)
    }

    { // Query a single user
        var (
            id        int
            username  string
            password  string
            createdAt time.Time
        )

        query := "SELECT id, username, password, created_at FROM users WHERE id = ?"
        if err := db.QueryRow(query, 1).Scan(&id, &username, &password, &createdAt); err != nil {
            log.Fatal(err)
        }

        fmt.Println(id, username, password, createdAt)
    }

    { // Query all users
        type user struct {
            id        int
            username  string
            password  string
            createdAt time.Time
        }

        rows, err := db.Query(`SELECT id, username, password, created_at FROM users`)
        if err != nil {
            log.Fatal(err)
        }
        defer rows.Close()

        var users []user
        for rows.Next() {
            var u user

            err := rows.Scan(&u.id, &u.username, &u.password, &u.createdAt)
            if err != nil {
                log.Fatal(err)
            }
            users = append(users, u)
        }
        if err := rows.Err(); err != nil {
            log.Fatal(err)
        }

        fmt.Printf("%#v", users)
    }

    {
        _, err := db.Exec(`DELETE FROM users WHERE id = ?`, 1)
        if err != nil {
            log.Fatal(err)
        }
    }
}

Templates - 略

Assets and Files

https://gowebexamples.com/static-files/

// static-files.go
package main

import "net/http"

func main() {
    fs := http.FileServer(http.Dir("assets/"))
    http.Handle("/static/", http.StripPrefix("/static/", fs))

    http.ListenAndServe(":8080", nil)
}

Forms

https://gowebexamples.com/forms/

// forms.go
package main

import (
    "html/template"
    "net/http"
)

type ContactDetails struct {
    Email   string
    Subject string
    Message string
}

func main() {
    tmpl := template.Must(template.ParseFiles("forms.html"))

    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        if r.Method != http.MethodPost {
            tmpl.Execute(w, nil)
            return
        }

        details := ContactDetails{
            Email:   r.FormValue("email"),
            Subject: r.FormValue("subject"),
            Message: r.FormValue("message"),
        }

        // do something with details
        _ = details

        tmpl.Execute(w, struct{ Success bool }{true})
    })

    http.ListenAndServe(":8080", nil)
}

Middleware (Basic)

https://gowebexamples.com/basic-middleware/

// basic-middleware.go
package main

import (
    "fmt"
    "log"
    "net/http"
)

func logging(f http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        log.Println(r.URL.Path)
        f(w, r)
    }
}

func foo(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "foo")
}

func bar(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "bar")
}

func main() {
    http.HandleFunc("/foo", logging(foo))
    http.HandleFunc("/bar", logging(bar))

    http.ListenAndServe(":8080", nil)
}

Middleware (Advanced)

https://gowebexamples.com/advanced-middleware/

// advanced-middleware.go
package main

import (
    "fmt"
    "log"
    "net/http"
    "time"
)

type Middleware func(http.HandlerFunc) http.HandlerFunc

// Logging logs all requests with its path and the time it took to process
func Logging() Middleware {

    // Create a new Middleware
    return func(f http.HandlerFunc) http.HandlerFunc {

        // Define the http.HandlerFunc
        return func(w http.ResponseWriter, r *http.Request) {

            // Do middleware things
            start := time.Now()
            defer func() { log.Println(r.URL.Path, time.Since(start)) }()

            // Call the next middleware/handler in chain
            f(w, r)
        }
    }
}

// Method ensures that url can only be requested with a specific method, else returns a 400 Bad Request
func Method(m string) Middleware {

    // Create a new Middleware
    return func(f http.HandlerFunc) http.HandlerFunc {

        // Define the http.HandlerFunc
        return func(w http.ResponseWriter, r *http.Request) {

            // Do middleware things
            if r.Method != m {
                http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
                return
            }

            // Call the next middleware/handler in chain
            f(w, r)
        }
    }
}

// Chain applies middlewares to a http.HandlerFunc
func Chain(f http.HandlerFunc, middlewares ...Middleware) http.HandlerFunc {
    for _, m := range middlewares {
        f = m(f)
    }
    return f
}

func Hello(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "hello world")
}

func main() {
    http.HandleFunc("/", Chain(Hello, Method("GET"), Logging()))
    http.ListenAndServe(":8080", nil)
}

Sessions

https://gowebexamples.com/sessions/

// sessions.go
package main

import (
    "fmt"
    "net/http"

    "github.com/gorilla/sessions"
)

var (
    // key must be 16, 24 or 32 bytes long (AES-128, AES-192 or AES-256)
    key = []byte("super-secret-key")
    store = sessions.NewCookieStore(key)
)

func secret(w http.ResponseWriter, r *http.Request) {
    session, _ := store.Get(r, "cookie-name")

    // Check if user is authenticated
    if auth, ok := session.Values["authenticated"].(bool); !ok || !auth {
        http.Error(w, "Forbidden", http.StatusForbidden)
        return
    }

    // Print secret message
    fmt.Fprintln(w, "The cake is a lie!")
}

func login(w http.ResponseWriter, r *http.Request) {
    session, _ := store.Get(r, "cookie-name")

    // Authentication goes here
    // ...

    // Set user as authenticated
    session.Values["authenticated"] = true
    session.Save(r, w)
}

func logout(w http.ResponseWriter, r *http.Request) {
    session, _ := store.Get(r, "cookie-name")

    // Revoke users authentication
    session.Values["authenticated"] = false
    session.Save(r, w)
}

func main() {
    http.HandleFunc("/secret", secret)
    http.HandleFunc("/login", login)
    http.HandleFunc("/logout", logout)

    http.ListenAndServe(":8080", nil)
}

JSON

https://gowebexamples.com/json/

This example will show how to encode and decode JSON data using the encoding/json package.

// json.go
package main

import (
    "encoding/json"
    "fmt"
    "net/http"
)

type User struct {
    Firstname string `json:"firstname"`
    Lastname  string `json:"lastname"`
    Age       int    `json:"age"`
}

func main() {
    http.HandleFunc("/decode", func(w http.ResponseWriter, r *http.Request) {
        var user User
        json.NewDecoder(r.Body).Decode(&user)

        fmt.Fprintf(w, "%s %s is %d years old!", user.Firstname, user.Lastname, user.Age)
    })

    http.HandleFunc("/encode", func(w http.ResponseWriter, r *http.Request) {
        peter := User{
            Firstname: "John",
            Lastname:  "Doe",
            Age:       25,
        }

        json.NewEncoder(w).Encode(peter)
    })

    http.ListenAndServe(":8080", nil)
}

Websockets

https://gowebexamples.com/websockets/

$ go get github.com/gorilla/websocket

// websockets.go
package main

import (
    "fmt"
    "net/http"

    "github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{
    ReadBufferSize:  1024,
    WriteBufferSize: 1024,
}

func main() {
    http.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) {
        conn, _ := upgrader.Upgrade(w, r, nil) // error ignored for sake of simplicity

        for {
            // Read message from browser
            msgType, msg, err := conn.ReadMessage()
            if err != nil {
                return
            }

            // Print the message to the console
            fmt.Printf("%s sent: %s\n", conn.RemoteAddr(), string(msg))

            // Write message back to browser
            if err = conn.WriteMessage(msgType, msg); err != nil {
                return
            }
        }
    })

    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        http.ServeFile(w, r, "websockets.html")
    })

    http.ListenAndServe(":8080", nil)
}

Password Hashing

https://gowebexamples.com/password-hashing/

$ go get golang.org/x/crypto/bcrypt

// passwords.go
package main

import (
    "fmt"

    "golang.org/x/crypto/bcrypt"
)

func HashPassword(password string) (string, error) {
    bytes, err := bcrypt.GenerateFromPassword([]byte(password), 14)
    return string(bytes), err
}

func CheckPasswordHash(password, hash string) bool {
    err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
    return err == nil
}

func main() {
    password := "secret"
    hash, _ := HashPassword(password) // ignore error for the sake of simplicity

    fmt.Println("Password:", password)
    fmt.Println("Hash:    ", hash)

    match := CheckPasswordHash(password, hash)
    fmt.Println("Match:   ", match)
}

END

本文链接：

https://www.cnblogs.com/luo630/p/18169977

ben 发布于博客园

posted @ 2024-05-04 10:10 快乐的欧阳天美1114 阅读(10) 评论(0) 编辑收藏举报

刷新页面返回顶部

`三一三`

用问题刺激思想，用执行消灭懒散，

golang 官方代码汇总

序章

go.dev 首页

Go Tutorials

Getting started

Create a module

Getting started with multi-module workspaces

Accessing a relational database

Developing a RESTful API with Go and Gin

Getting started with generics

Getting started with fuzzing

Getting started with govulncheck

Find and fix vulnerable dependencies with VS Code Go

Go Web Examples

Hello World

HTTP Server

Routing (using gorilla/mux)

MySQL Database

Templates - 略

Assets and Files

Forms

Middleware (Basic)

Middleware (Advanced)

Sessions

JSON

Websockets

Password Hashing

END

公告

`三一三`

用问题刺激思想，用执行消灭懒散，

golang 官方代码 汇总

序章

go.dev 首页

Go Tutorials

Getting started

Create a module

Getting started with multi-module workspaces

Accessing a relational database

Developing a RESTful API with Go and Gin

Getting started with generics

Getting started with fuzzing

Getting started with govulncheck

Find and fix vulnerable dependencies with VS Code Go

Go Web Examples

Hello World

HTTP Server

Routing (using gorilla/mux)

MySQL Database

Templates - 略

Assets and Files

Forms

Middleware (Basic)

Middleware (Advanced)

Sessions

JSON

Websockets

Password Hashing

END

公告

golang 官方代码汇总