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修改Lissajour服务，从URL读取变量，比如你可以访问

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修改Lissajour服务，从URL读取变量，比如你可以访问 http://localhost:8000/?cycles=20 这个URL，这样访问可以将程序里的cycles默认的5修改为20。字符串转换为数字可以调用strconv.Atoi函数。你可以在godoc里查看strconv.Atoi的详细说明。

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package main
import (
"fmt"
"log"
"net/http"
"image/gif"
"image"
"math"
"math/rand"
"io"
"image/color"
"strconv"
)
var palette = []color.Color{color.White, color.Black}
const (
whiteIndex = 0 // first color in palette
blackIndex = 1 // next color in palette
)
func lissajous(out io.Writer, myCycles float64) { //接收 cycles参数
const (
cycles  = 5     // number of complete x oscillator revolutions
res     = 0.001 // angular resolution
size    = 100   // image canvas covers [-size..+size]
nframes = 64    // number of animation frames
delay   = 8     // delay between frames in 10ms units
)
if myCycles == 0 {
myCycles = cycles //如果为零，则使用常亮定义的值
}
freq := rand.Float64() * 3.0 // relative frequency of y oscillator
anim := gif.GIF{LoopCount: nframes}
phase := 0.0 // phase difference
for i := 0; i < nframes; i++ {
rect := image.Rect(0, 0, 2*size+1, 2*size+1)
img := image.NewPaletted(rect, palette)
for t := 0.0; t < myCycles*2*math.Pi; t += res
  { //使用myCycles变量
x := math.Sin(t)
y := math.Sin(t*freq + phase)
img.SetColorIndex(size+int(x*size+0.5),
  size+int(y*size+0.5),
blackIndex)
}
phase += 0.1
anim.Delay = append(anim.Delay, delay)
anim.Image = append(anim.Image, img)
}
gif.EncodeAll(out, &anim) // NOTE: ignoring encoding errors
}
func handler(w http.ResponseWriter, r *http.Request)  {
fmt.Fprintf(w, "%s %s %s\n", r.Method, r.URL, r.Proto)
fmt.Fprintf(w, "URL.Path = %q\n", r.URL.Path)
}
func handler_gif(w http.ResponseWriter,r *http.Request) {
if err := r.ParseForm(); err != nil {
log.Print(err)
}
if r.Form["cycles"] != nil { // 获取cycles参数，并转为int型
cycles,err := strconv.Atoi(r.Form["cycles"][0])
if err != nil {
lissajous(w,float64(cycles))
}
}
lissajous(w,float64(0))
}
func main() {
http.HandleFunc("/", handler) // each request calls
  handler
http.HandleFunc("/gif", handler_gif) // each request
  calls handler
log.Println("localhost:8000")
log.Fatal(http.ListenAndServe("localhost:8000", nil))
}

发表于 2018-07-12 20:41:27 回复(0)